tag:blogger.com,1999:blog-52575365119210945732024-03-21T17:34:47.878-07:00The World in the BoxAn Online Resource for Students of Geography in Hawai'iGeografika Nusantarahttp://www.blogger.com/profile/02009398091652720545noreply@blogger.comBlogger9125tag:blogger.com,1999:blog-5257536511921094573.post-52411817071153166372014-07-11T16:27:00.002-07:002014-07-11T16:29:32.757-07:00What is El Niño, and How Does it Affect Hawai'i?If you ever pay attention to the weather forecast, you’ve probably heard about a phenomenon called El Niño. However, if you’re like most people, you probably don’t have a clue as to what El Niño refers to or what it means. You may have the vague notion that it causes changes in the weather, but you might be unsure at to the nature of those changes. For example, does it make it rain more? Less? Does it make it hotter or cooler? This confusion is understandable, because the effects of El Niño vary depending on where you are! In this post we’re going to dispel some of the mystery and confusion surrounding El Niño in general and explain how this phenomenon affects Hawai’i. Looking at El Niño gives us the chance to examine a number of other aspects of the oceanic-atmospheric relationship, and helps us to think about oceans and the atmosphere as a big system. You may find this information useful, since many climatologists are predicting unusually strong El Niño conditions for 2014.<br />
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<h2>
Explaining ENSO</h2>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWV5HsFpYJi0J_6w12qWImfvlbSSEGhsGm0U-Dxf23OfuIZSq5sKQTjVJMn-lx_4_2f4qt4PDWNLAjto2ObWaejpg7TWmlq3nfQSCCh96YlhIqyy_c0PSkvaL63Y70DwUbmiHnIFtJsJPt/s1600/Mean_sst_equatorial_pacific.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWV5HsFpYJi0J_6w12qWImfvlbSSEGhsGm0U-Dxf23OfuIZSq5sKQTjVJMn-lx_4_2f4qt4PDWNLAjto2ObWaejpg7TWmlq3nfQSCCh96YlhIqyy_c0PSkvaL63Y70DwUbmiHnIFtJsJPt/s1600/Mean_sst_equatorial_pacific.gif" height="400" width="267" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Map from <a href="http://en.wikipedia.org/wiki/Walker_circulation">Wikipedia</a>.</td></tr>
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El Niño, which means “the (male) child” in Spanish, is actually part of a larger periodic cycle that affects ocean currents around the equator in the Pacific Ocean. This cycle is called the El Niño Southern Oscillation, or ENSO for short. Before explaining ENSO, though, let’s look at how the equatorial Pacific Ocean usually works. A good place to start is the trade winds. In Hawai’i we know that the trade winds generally blow from the northeast, and are generally very reliable in the summer. These winds provide a nice breeze and keep the weather pleasant most of the time. The trade winds are part of a pattern of atmospheric circulation called the Hadley Cell circulation, which we’ve explained elsewhere. These winds flow across the Pacific towards the equator, and because of the Coriolis effect (from the rotation of the earth), they also blow towards the west. Related to this is another pattern called the Walker circulation, which causes the prevailing winds to blow towards the west along the equator. This is because the air pressure is normally high around Tahiti due to sinking air. The wind always blows out of high pressure areas. In contrast, by Australia and Indonesia the air pressure is low, which means that air is rising up through the troposphere. Wind always blows into low pressure areas. The wind pushes the water towards the west, and so the warm equatorial water tends to pool in the western Pacific around Southeast Asia and Australia. These are the normal conditions, as you can see in the diagram. There are some interesting aspects to this circulation pattern. For example, it causes the thermocline to be deeper in the western Pacific. It also makes sea level slightly higher in the western Pacific. When this pattern is particularly strong we call it “La Niña”, which in Spanish means “the (girl) child”. La Niña conditions tend to decrease rainfall in the eastern Pacific in places like southern California. <br />
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As you can see from the maps in the above paragraph, this means that the water temperature is higher in the western Pacific. This means that there is a lot of evaporation, which provides moisture to the equatorial regions of South and Southeast Asia. At the same time, the water is much cooler off the coast of South America. Since the wind normally blows to the west, this draws water away from South America, which in turn pulls up cold water from the depths below. This nutrient-rich water creates the richest fishing area on the planet. <br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeahh4R46HWSfR55gzfRHbC7_dpv2bTILVAev3bnWFRyzP6OsaceykPVIeQXDLQEZw8KRqwG6UqWwiOf2M33Rk0V58zeeBdBw5W4rEpx4gerLBbO1v8P2n3O7TJygE-MJRC0_SQuqfyBzf/s1600/WalkerCirc_large.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeahh4R46HWSfR55gzfRHbC7_dpv2bTILVAev3bnWFRyzP6OsaceykPVIeQXDLQEZw8KRqwG6UqWwiOf2M33Rk0V58zeeBdBw5W4rEpx4gerLBbO1v8P2n3O7TJygE-MJRC0_SQuqfyBzf/s1600/WalkerCirc_large.jpg" height="504" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Graphic from <a href="http://www.windows2universe.org/earth/Atmosphere/walker_circulation.html&edu=mid">Windows to the Universe</a>.</td></tr>
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<h2>
Reversing the Walker Circulation</h2>
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Every now again, however, the westward flow of the Walker Circulation weakens or even shuts down all together. On average, this happens about every 2-8 years. When the winds weaken, the warm water that has pooled in the western Pacific starts to move back towards the east (1), since the wind is no longer pushing it. The difference in air pressure between Tahiti and Indonesia is much less in this case, and in some instances the trade winds will actually blow in the opposite direction. The term “El Niño” refers to these conditions. El Niño has significant effects not only on ocean temperatures, but wind and weather throughout the Pacific and beyond. Areas in the eastern Pacific get abnormally wet, whereas the western Pacific is drier. For example, the strong El Niño in 1998 caused widespread storms across the western part of the United States.<br />
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This has indirect effects on humans, as it can lead to droughts in India, China, and other places in Asia. Historically El Niño conditions have contributed to some of the most devastating famines in history (2). There are economic effects as well. For example, when El Niño occurs it shuts down the cold water upwelling off the coast of Peru that plays such a large role in the fisheries there. The fisheries industry is extremely hard hit when this happens, which in turn affects the entire economy of Peru. At the same time, the Polynesian wayfinders that initially discovered and settled in Hawai’i and other islands in the Pacific had a keen understanding of El Niño. The periodic reversal of the trade winds allowed them to expand to islands and archipelagoes that would have been much more difficult to reach under normal conditions.<br />
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<h2>
El Niño’s Impacts on Hawai’i</h2>
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Now that we understand the basics of El Niño, we can begin to look at how this curious phenomenon affects the weather here in Hawai’i. Both La Niña and El Niño seem to affect our rainfall patterns. As you know, Hawai’i has two seasons: the dry Kau season, which runs from about May to September or October, and the wetter Ho’oilo season, which lasts from October to May. When there is a particularly strong La Niña, the Kau season tends to be significantly wetter, whereas the El Niño phase generally correlates with much lower rainfall totals (and even drought) during the Ho’oilo season. In addition, during La Niña the normal wet season is often abnormally wet. For example, in early 2006 Hawai’i experienced 40 straight days of rain during the La Niña wet season. You can see the pattern illustrated in the rainfall maps of Maui and Kahoolawe. Since this year is an El Niño year, many experts are expecting drier than average conditions starting in around October. However, as we were writing this blog it was still uncertain as to how strong the 2014 El Niño would turn out to be.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiH7halRWidESrKH95iNpJl-9uPN9d9JZ2QEuOb-yAmnRznTfkgjJkE2_m_EPynC8RflgapGMc1WZDkg_X8fdGm3El6dwk28TYSbsLX4e-5MhH8d05wl2roGWxroe4xAyLXfG9-qZVeHBFx/s1600/Maui+Rain.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiH7halRWidESrKH95iNpJl-9uPN9d9JZ2QEuOb-yAmnRznTfkgjJkE2_m_EPynC8RflgapGMc1WZDkg_X8fdGm3El6dwk28TYSbsLX4e-5MhH8d05wl2roGWxroe4xAyLXfG9-qZVeHBFx/s1600/Maui+Rain.JPG" height="380" width="640" /></a></div>
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Climatologists and other researchers at the University of Hawai’i are currently carrying out work to deepen our understanding of ENSO’s effects on the archipelago. For example, one research project is focusing on how microclimatic variables such as solar radiation, relative humidity, temperature and potential evapotrasporation respond to ENSO phase changes in different seasons here. Other work focuses on quantifying the effects of ENSO on the dry season, since the dry season is often downplayed as ENSO is generally discussed as a wet season phenomenon in the context of Hawai’i. <br />
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Although we understand the basics of ENSO, looking into the future there is still a lot of uncertainty surrounding the phenomenon. One big unknown is how the ENSO cycle will be affected by climate change. It is likely that one or more of the physical processes that are responsible for determining the characteristics of ENSO will be modified by climate change, but it isn’t yet possible to reliable speculate as to whether ENSO activity will be enhanced or dampened, or if the frequency of events will change. Thus there are exciting frontiers of climate research that you might someday contribute to as you continue your studies of geography and atmospheric processes. <br />
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<h2>
Notes </h2>
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(1) This reverse flow is called a “Kelvin wave”. <br />
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(2) For an outstanding account of how El Niño, coupled with colonial administrative policies, contributed to famines in 19th century, see Mike Davis’s Late Victorian<br />
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Geografika Nusantarahttp://www.blogger.com/profile/02009398091652720545noreply@blogger.com0tag:blogger.com,1999:blog-5257536511921094573.post-87532464876196801252014-05-26T16:12:00.001-07:002014-05-26T16:12:03.212-07:00A "New" Hawaiian Volcano!<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijtli4P5IZUZ3if0Irege802D_0iHZnywvtoJnABlG3IIZw_7nJrFqtZ4QdVESAqx8WEOoUBhvQyfOspFK3tRt_oUqVDmAhSrwwdZZjP_rNG11sYogb3Sn-7MgTawvYzIa2gUPt8kOtJlG/s1600/Mpa+of+the+volcano.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijtli4P5IZUZ3if0Irege802D_0iHZnywvtoJnABlG3IIZw_7nJrFqtZ4QdVESAqx8WEOoUBhvQyfOspFK3tRt_oUqVDmAhSrwwdZZjP_rNG11sYogb3Sn-7MgTawvYzIa2gUPt8kOtJlG/s1600/Mpa+of+the+volcano.jpg" height="350" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Image from Sinton et al 2014 (see references).</td></tr>
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Virtually everyone living in Hawai'i knows that the islands are volcanic in origin; if you live in Honolulu it's hard to miss obviously volcanic features such as Lē'ahi (Diamondhead), Kohelepelepe (Koko crater), and Puowaina (Punchbowl). And nearly everyone has seen striking pictures and videos of the ongoing eruptions at Pu'u 'Ō'ō on the Big Island. However, most people are probably not aware of the details of the lifecycle of our islands; they are born and eventually, just like all of us, they fade away into the sunset. What's even more interesting is that our understanding of these events is constantly evolving and being refined by scientists, many of whom work at the University of Hawai'i. <br />
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In fact, our knowledge of the island of Oahu was recently enhanced by an exciting discovery revealed by a research team led by geologists at the University of Hawai'i. Previously the conventional thinking was that Oahu was formed by two <b><i>shield </i></b>volcanoes: the Ko'olau volcano and the Wai'anae volcano. However, the recently announced discovery indicates that there is in fact a third shield volcano which makes up part of the island of Oahu. The newly-discovered volcano has been called Ka'ena by its discoverers, and is located approximately 20 kilometers off the coast of Ka'ena point. In this post we'll tell you about the "new" volcano, but first we describe the context with a sort of "primer" as to how the island of Oahu formed in the first place.<br />
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<h2>
Hot Spot Volcanism</h2>
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The first thing to understand is that our volcanoes are special and differ from other volcanoes you might be familiar with, like Mt. Fuji, Mt. Pinatubo, and Mt. Saint Helen's. This is because they form above a hot spot, which is an upwelling of mantle from deep within the earth. The composition of the magma that flows out of our volcanoes is different from most other volcanoes found on continents or island arcs in that it flows much more freely and has a lower solidification point. Practically speaking this means that the lava(1) can flow further away from the vent, and also that it doesn't plug up the vent, and so instead of a "classic" <b>cinder cone</b> volcano (like Mt. Fuji), our volcanoes grow much bigger and have gently sloping sides. Indeed, our volcanoes are called "shield" volcanoes because they resemble a warrior's shield that has been laid upon the ground.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEif4S-diwgzu2A5j_dm5wD8y31fsh5L0K4XsYyJghdEt-6-9SE4vwOqKrR9JxODeKQKCH52xoUzIOgmdw-r9dITpNAB_xk2jNnQQb6obbg8d0ebOaUDgJdCmCiS9P_8xZxl7cqEKSAqFQF1/s1600/Shield+vs+cinder+cone+volcano.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEif4S-diwgzu2A5j_dm5wD8y31fsh5L0K4XsYyJghdEt-6-9SE4vwOqKrR9JxODeKQKCH52xoUzIOgmdw-r9dITpNAB_xk2jNnQQb6obbg8d0ebOaUDgJdCmCiS9P_8xZxl7cqEKSAqFQF1/s1600/Shield+vs+cinder+cone+volcano.jpg" height="282" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Relative size of cinder and shield volcanoes. Graphic from US Geological Survey.</td></tr>
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Another important thing to understand about our volcanoes is that while the hot spot doesn't move, the islands themselves do! This is because the earth's surface is made up of a number of <b><i>tectonic plates</i></b> that move around due to convection currents within the mantle of the earth. While a full description of plate tectonics will have to wait until a later post, we can understand that the tectonic plate upon which are islands sit (the Pacific plate) is moving in a northwesterly direction at about the same speed at which your fingernails grow. This is why we have a chain of volcanic islands and not just one big island. <br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5KzhtvGkKnEggHvivfmHE1PO-eDFHOEfUK2paMs5C1X2DGvdffz3Jst_t34qbLKHE5Y7xivL5i6Ds7ryDkwfHDeFSblODR2cxCE-Ta4fVGCE-aERrVFrHjtYZsU_kqha11jI4GY68lvhI/s1600/Hawaii_hotspot_cross-sectional_diagram.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5KzhtvGkKnEggHvivfmHE1PO-eDFHOEfUK2paMs5C1X2DGvdffz3Jst_t34qbLKHE5Y7xivL5i6Ds7ryDkwfHDeFSblODR2cxCE-Ta4fVGCE-aERrVFrHjtYZsU_kqha11jI4GY68lvhI/s1600/Hawaii_hotspot_cross-sectional_diagram.jpg" height="334" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Diagram from <a href="http://en.wikipedia.org/wiki/File:Hawaii_hotspot_cross-sectional_diagram.jpg">Wikipedia</a>. </td></tr>
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<h2>
Stages in the Lifecycle of a Hawaiian Island Volcano</h2>
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Now that we understand the fundamental difference between Hawaiian shield volcanoes and cinder cones, we can understand the various stages in the lifecycle of the Hawaiian Islands. You might have noticed that the Big Island, which is currently still experiencing volcanic activity and is still growing, is far larger than the other islands in the <b><i>archipelago</i></b>, and that as you move towards the northwest the islands seem to get smaller and smaller, until finally you find very small <b><i>atolls </i></b>of Kure and Midway. This is no coincidence. This section will help you understand why this is the case. <br />
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<b><u>1. Preshield Stage</u></b>. This first stage happens deep in the depths of the ocean', several kilometers beneath the surface where there intense pressure due to the weight of the water above. The preshield stage is characterized by infrequent, small-volume eruptions which produce pillow lava. As the volcano grows the composition of the lava changes. The volcano erupts more often, and produces more and more lava. When this happens the new undersea volcano enters the second stages. It is very hard to observe the preshield stage due to the extreme depths and the fact that these vents are so hard to locate.<br />
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<b><u>2. Submarine Shield Stage</u></b>. This stage features continued effusive eruptions of pillow lava deep<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQtMt6pht-nF3348kJSPlNQiIvawQRRfHw-nYqLJ8762Ew9aMobcynihxDKiCMwiNsQdCEeP14QEL5SWKBYbqsGGVNAk-Bcg6iTnwSU3699GwKFvB-7j0FKCwplQ67V6JZd1OWlrBONA4N/s1600/Loihi_3d.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQtMt6pht-nF3348kJSPlNQiIvawQRRfHw-nYqLJ8762Ew9aMobcynihxDKiCMwiNsQdCEeP14QEL5SWKBYbqsGGVNAk-Bcg6iTnwSU3699GwKFvB-7j0FKCwplQ67V6JZd1OWlrBONA4N/s1600/Loihi_3d.gif" height="220" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: 12pt;">Lō'ihi image from <a href="http://en.wikipedia.org/wiki/File:Loihi_3d.gif">Wikipedia</a>.</span></td></tr>
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beneath the surface of the ocean. The undersea volcano grows into a huge mountain. Here in the Hawaiian islands the Lō'ihi volcano, which is located approximately 1000 meters beneath the surface of the ocean about 35 kilometers southeast of the Big Island, is in the submarine shield stage. Volcanologists expect Lō'ihi to breach the surface and become our newest island within the next 100,000 years. </div>
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<b><u>3. Explosive Stage</u></b>. The shield volcano enters this stage when the top of the erupting volcano begins to approach the surface of the ocean and the lava and ocean water mix to produce explosive eruptions. Think about squirting a water gun at a campfire. It sizzles, right? Well, the explosive stage in the volcano's life cycle is based on the same principle, only a bazillion times bigger. Currently there are no volcanoes in Hawaii in this stage, but Hunga Ha'apai island in Tonga is. </div>
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<b><u>4. Subaerial Shield Stage</u></b>. After enough ash, debris, and other volcanic matter accumulates such that the volcano is no longer erupting into the sea but rather upon its own flanks it is said to have entered the subaerial shield stage. Since the lava is no loner in direct contact with water when it is extruded the eruptions are much calmer. Currently Kilauea on the Big Island is in this stage. During this stage eruption rates increase and the island grows rapidly over a period of approximately half a million years.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvpJI-BjIbVl_gfHIlgtMjv73fe16-kswkW10wJllAhsS86_Nj0JYPka2MUm75qPw6YF1HTp3zJvQ5dbHqEBGVWTPwDUVgNMMwNBUnrR21rEaivNMCKsLUQ1FKwfDrhQ8Q_T7-vKeKFsLD/s1600/Kilauea_map.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvpJI-BjIbVl_gfHIlgtMjv73fe16-kswkW10wJllAhsS86_Nj0JYPka2MUm75qPw6YF1HTp3zJvQ5dbHqEBGVWTPwDUVgNMMwNBUnrR21rEaivNMCKsLUQ1FKwfDrhQ8Q_T7-vKeKFsLD/s1600/Kilauea_map.gif" height="490" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Kilauea is currently in the subaerial shield forming stage. Map from <a href="http://www.gsvdl.net/photos/hawaii/kilauea.shtml">here</a>.</td></tr>
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<b><u>5. Capping (postshield) stage</u></b>. For some of the volcanoes, once they get to be high enough the composition of the lava they produce changes. This different lava produces steep peaks on the top of the volcano that look like pointy hats. If you've ever been up top he top of Mauna Kea you've probably noticed the steep landforms; these are the products of the capping stage. However, it seems that not all of the volcanoes experience this stage; Ko'olau and Lana'i are notable exceptions. Eruption rates slow significantly during this stage until the volcano stops erupting all together. </div>
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<b><u>6. Erosional Stage</u></b>. Though this stage is usually presented as the 6th of 9 stages, it really begins as soon as the volcano breaches the surface of the ocean, as mother nature's erosive forces in the form of wind, waves, and rain immediately set to work tearing the new island apart. However, the effects of these destructive forces are most apparent after the volcano has stopped erupting, and the island continues to be dissected. You can really see the effects of erosion when you look at the elevation model maps of Oahu, which stopped erupting more than a million years ago, and the Big Island, which is still erupting today. Note how rough the terrain of Oahu is compared to the Big Island; this is due to erosion. <br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEhTHOg2Ulap89G4OIn4wz9bkvmOCLC3y4gWrlPxVbbooa3AAmtSXtTMlBUeL2GUsRDOS_OEEe6MUhMyGooOOJFDj8iivPYUsNl9CxTe_tNZvqzBqWeBq4IT4fwMHL1Mc02tysYKpR1Cdw/s1600/hawaii_dem.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEhTHOg2Ulap89G4OIn4wz9bkvmOCLC3y4gWrlPxVbbooa3AAmtSXtTMlBUeL2GUsRDOS_OEEe6MUhMyGooOOJFDj8iivPYUsNl9CxTe_tNZvqzBqWeBq4IT4fwMHL1Mc02tysYKpR1Cdw/s1600/hawaii_dem.jpg" height="640" width="564" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">This image of Hawai'i island and the below image of Oahu are <i>digital elevation models </i>(DEM) showing the topography of the islands. Remember that these are not to scale; the Big Island is far larger than Oahu. However, can you make any general observations about the topography of these islands? What do you think explains these observations? Images from SOEST UH. </td></tr>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKkrapExYzbGByG2Kui3-y2ds2FGmvD7iwfKUDso7pztoOfQToSODKVpqDWASHKTOWKFZ3emJZDr06twgNwy-MsHpaabkaElCpxqCiztwi2dHVI7d6m1_UCXgFOkfpIy5pkoPYgbo-iyoP/s1600/oahu_dem.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKkrapExYzbGByG2Kui3-y2ds2FGmvD7iwfKUDso7pztoOfQToSODKVpqDWASHKTOWKFZ3emJZDr06twgNwy-MsHpaabkaElCpxqCiztwi2dHVI7d6m1_UCXgFOkfpIy5pkoPYgbo-iyoP/s1600/oahu_dem.jpg" height="490" width="640" /></a></div>
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<b><u>7. Renewed volcanism (rejuvenated) stage</u></b>. The seventh stage is one of the most fascinating and least understood stages. It is clear that at some point long after (in some cases millions of years) the shield volcano stops erupting, new lava flows and hydromagmatic eruptions occur, which seem to be much more violent but much smaller than the shield volcano eruptions. Virtually all of the craters on Oahu are examples of this stage, as are Kūpikipiki'ō (Black Point) and the Sugarloaf flow out of Mānoa valley. There are a number of hypotheses to explain renewed volcanism and a full discussion is beyond the scope of this blog post. This stage seems to continue for a long period of time, and some geologists date some of the volcanic activity over on the Waimanalo side as recently as 4,000 years ago, so it seems to me that Oahu is probably still in this stage! <br />
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<b><u>8. Atoll stage</u></b>. After the rejuvenated period ends, the islands continue to erode and erode for millions<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmbw3PWwg68mZY_wCA-YjAcE5AiIFYCvvjjfSukJCkcf6T0i2b1100VfofhoRDdMtjlyn_WyO6-luUSgasdSxaX9p23mCa9cPgAA3MN_8h7Y16EtjG8bQtUbXOlBTx56ie2bBwbUR53xQf/s1600/Kure+Atoll.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmbw3PWwg68mZY_wCA-YjAcE5AiIFYCvvjjfSukJCkcf6T0i2b1100VfofhoRDdMtjlyn_WyO6-luUSgasdSxaX9p23mCa9cPgAA3MN_8h7Y16EtjG8bQtUbXOlBTx56ie2bBwbUR53xQf/s1600/Kure+Atoll.jpg" height="287" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Kure atoll image from <a href="http://www.papahanaumokuakea.gov/visit/kure.html">here</a>. The Hawaiian name for Kure<br />atoll is Moku <span style="font-size: x-small;">Pāpapa.</span><span style="font-size: 12pt;"> </span> </td></tr>
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of years, until there is nothing left. However, since the Hawaiian islands are in warm tropical water, the growth of the island during the earlier stages provides an ideal habitat for corals, which over thousands and millions of years build reef structures which fringe the islands. And although the island itself has eroded away because there are no more eruptions, the development of the coral reef is a biological activity that is only indirectly linked to the volcanoes, and so it continues as long as the water around the islands is warm enough for corals to grow. Hence what remains when the island erodes away is an atoll, or coral island. Midway and Kure islands are good examples of Hawaiian islands in the atoll stage. <br />
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<b><u>9. Guyot (seamount stage)</u></b>. The last stage begins when the islands are pulled by the tectonic drifting of the Pacific plate out of water warm enough to support coral. When this happens the reefs stop growing and eventually sink back into the sea, and so all that is left is a high spot on the ocean floor, known as a "seamount" or a "guyot". Since these are beneath the surface of the water you can't see these, but they are very clear from sonar imagery. There is a long chain of seamounts extending to the north all the way up to the Aleutian trench, where the seamounts are being subducted back into the earth's bowels by the slow grind of tectonic forces. This is where the Hawaiian islands finally pass into oblivion. We have no idea how many islands there have been in the past, but we do know that the oldest seamount is approximately 81 million years old. The seamounts are called the "Emperor Seamounts" and are named for Japanese emperors. <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7OO4srodlsGbRD4VZt8ZwCtE33IhhKtb9CbngKFreHxV7MusSk-AFS3fkMsMT7NKFul_8gkzCmoHQFe5SVugZ027pLFa8jBjyx4toCjGfZqL4XiQnCYD_iejZRtm-wTxf_6LzedX-wJqg/s1600/seamounts.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7OO4srodlsGbRD4VZt8ZwCtE33IhhKtb9CbngKFreHxV7MusSk-AFS3fkMsMT7NKFul_8gkzCmoHQFe5SVugZ027pLFa8jBjyx4toCjGfZqL4XiQnCYD_iejZRtm-wTxf_6LzedX-wJqg/s1600/seamounts.jpg" height="590" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The Hawaiian Islands and Emperor Seamounts. Note the "bend" in the line of volcanoes, which indicates a shift<br />in the motion of the tectonic plates. "My" means "million years" and indicates the age of the volcano.</td></tr>
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<h2>
The Ka'ena Volcano</h2>
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Dr. John Sinton of the Department of Geology at the University of Hawai'i conducted the research that confirmed the existence of the Ka'ena volcano. Based on maps of the sea floor, scientists had long suspected that there was third volcano, but until Dr. Sinton's research, no one could say for sure. The way that Dr. Sinton and his team made the distinction was by collecting rock samples from beneath the ocean's surface off the coast of Ka'ena point using remotely-operated undersea vehicles (robots). They compared the chemical composition of these rocks with other rocks taken from the Wai'anae volcano. Geologists are able to look at the chemical building blocks of rocks, the actual minerals that make up the rock, for clues as to where the rock came from and how it was formed. Each rock has its own chemical fingerprint. This analysis confirmed that the lava that produced each of the rocks is chemically distinct. <br />
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According to Dr. Sinton's research, the Ka'ena volcano erupted before the Wai'anae and Ko'olau volcanoes, approximately 5 million years ago. Thus the Ka'ena volcano had to grow from the bottom of the sea, and eventually reached a height of about 3,000 feet above sea level. The Wai'anae volcano was eventually much higher, but it didn't have to grow from the very bottom of the sea and was instead able to use the Ka'ena volcano as a sort of stepping stone. The discovery is really important because it addresses some questions geologists and geographers had about the hot-spot explanation for the Hawaiian volcanoes. Most of the volcanoes are between 20 and 40 kilometers apart, but there is a gap of about 90 kilometers between the Wai'anae volcano on Oahu and the volcano that formed the island of Kaua'i. Before the recent discovery no one could figure out why there was such a big gap between these two volcanoes. Now we understand that there isn't really that big a gap since the Ka'ena volcano is approximately 20-30 kilometers off the coast of Oahu, which is very consistent with the spacing between all of the other volcanoes. </div>
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So from all of this we can see what makes geography such an exciting field. It's always changing and constantly being updated. Even as we write this blog post research teams from UH and elsewhere are investigated the Ka'ena volcano cite to learn more about the genesis of the islands we call home. Next time your out at Ka'ena Point, you can gaze out across the sea and think about how Oahu must have looked 3-4 million years ago! </div>
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<h2>
Notes</h2>
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(1) We use the term <b><i>magma</i></b> to refer to molten (melted, liquid) rock when it is beneath the earth's surface. The term <b><i>lava</i></b> is used when it has been extruded onto the earth's surface.</div>
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<h2>
References and For Further Reading</h2>
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Sinton, John M., Deborah E. Eason, Mary Tardona, Douglas Pyle, Iris van der Zander, Herve Guillou, David A. Clague and John J. Mahoney. 2014. Ka'eana Volcano--A Precursor Volcano of the Island of O'ahu, Hawai'i. Geological Society of America Bulletin. </div>
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UH News story on Dr. Sinton's research:</div>
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http://www.hawaii.edu/news/2014/05/16/precursor-volcano-to-the-island-of-oahu-discovered/</div>
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Geografika Nusantarahttp://www.blogger.com/profile/02009398091652720545noreply@blogger.com0tag:blogger.com,1999:blog-5257536511921094573.post-49619099373355353812014-01-21T16:43:00.003-08:002014-01-21T16:43:57.658-08:00A Storm is Coming: Winter Weather Patterns In Hawaii<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXaR7QE03q9vWj_Eq0zThRTDy3h8_RlMP57M10yRa71mNYQkqJwqnGhOK04Gj8fHE59fqQYhmP3plZA31-c2u7aJ59UFCIEgfF8vkZK7tJ1Jw5AMpnvo3vzAEw6UIHf2QEir5jF11wvFQh/s1600/Approaching+Cold+Front.JPG" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXaR7QE03q9vWj_Eq0zThRTDy3h8_RlMP57M10yRa71mNYQkqJwqnGhOK04Gj8fHE59fqQYhmP3plZA31-c2u7aJ59UFCIEgfF8vkZK7tJ1Jw5AMpnvo3vzAEw6UIHf2QEir5jF11wvFQh/s1600/Approaching+Cold+Front.JPG" height="292" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Pacific Surface Analysis showing approaching cold front</td></tr>
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One of the main reasons that millions of tourists flock to Hawai'i each year is because the weather year round is fairly pleasant and predictable, and not as subject to the seasonal shifts that characterize the climate at higher latitudes. But if you've spent any time in Hawai'i you've likely noticed that there are indeed seasonal shifts. In the "summer" it's usually a little bit warmer, but the refreshing tradewinds blow a good bit more regularly, which helps to cool us off and brings rain to windward and <i>mauka </i>areas. In the "winter" the trades aren't as reliable, and we have more frequent <i>kona </i>winds. The Hawaiians, being excellent geographers, have names for these two seasons. The warmer season is called <b>Kau </b>and generally lasts from approximately mid to late April until October, whereas the cooler season is called <b>Ho'oilo</b> and lasts from mid to late October until April. The changes that come with Ho'oilo are the subject of this blog post.<br />
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<h3>
The Big Picture...</h3>
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One major feature of Ho'oilo is the periodic occurrence of thunderstorms, which in general are relatively rare in Hawai'i due to the <b>tradewind temperature inversion</b>. However, in the winter months, cold air and low pressure systems sweep down from the north, bringing occasionally severe weather along with the massive swells that the North Shore is so famous for. But did you know that these storms are a part of the global system of atmospheric circulation? It all begins with the earth-sun relationship, which you can read about in a previous post. Since the earth is tilted, the point on the earth's surface that receives the sun's energy directly shifts over the course of the year, which basically means that the latitude that receives the most energy migrates over the course of the year. This spot, called the <b>subsolar point</b>, is loosely tied to the <b>Inter-Tropical Convergence Zone</b> (ITCZ), an area of convection (rising air) and thunderstorms that helps to drive the entire global atmospheric circulation system! You've probably learned in geography class about the ITCZ, which is part of the three cell model of circulation (1).<br />
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As with most everything in life, whatever goes up must come down. This is true for air that rises in <b>coriolis </b>effect (to be discussed in a future post), which twists the path of the air (to the right in the northern hemisphere, to the left in the southern hemisphere. This part of the global atmospheric circulation is referred to as the <b>Hadley Cell</b>, and there are two of them, one to the north of the ITCZ and one to the south. You can see the general pattern in the figure below, which shows the circulation when it is summer in the northern hemisphere.<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqMveF6dRdsDvkHmdsvmK9Ug-h6Qu-3yAtvuJBJupMM2qGGM6an0migl3Czu8FoN4jmQrAFMYTvcWginhR_V3yYTCE7rkX4P-p-0vLSMLE8C_ZAiz700oHQvaYORG19EwjMGoz__bLBmTL/s1600/threecell_3d.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqMveF6dRdsDvkHmdsvmK9Ug-h6Qu-3yAtvuJBJupMM2qGGM6an0migl3Czu8FoN4jmQrAFMYTvcWginhR_V3yYTCE7rkX4P-p-0vLSMLE8C_ZAiz700oHQvaYORG19EwjMGoz__bLBmTL/s1600/threecell_3d.jpg" height="270" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Three Cell Model diagram from <a href="http://apollo.lsc.vsc.edu/classes/met130/notes/chapter10/three_cell.html">here</a>.</td></tr>
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the ITCZ. Once it reaches the top of the troposphere (the lowest layer of the atmosphere where virtually all weather happens), it diverges and circulates to the north and the south, sinking at approximately 30 degrees north and south of the equator, but the latitude at which the air sinks shifts along with the ITCZ and the subsolar point over the course of the year. The places where this air sinks are high pressure areas, because the sinking air is exerting force on anything below it. The ITCZ, conversely, is a low pressure area because the air is rising there. Because of the rotation of the earth, the sinking air is subject to the <br />
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<h3>
How this Affects Hawai'i...</h3>
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As you can see, a major area of sinking air is usually located to the northeast of Hawaii. Here in Hawaii we call this high pressure area the "<b>Hawaiian High</b>", but in general it referred to as the Northern Pacific Subtropical Anticyclone. Anticyclones are areas of sinking air where the wind circulates outward from the high in a clockwise direction. Note from the graphic the direction that the wind blows coming out of the high. You should notice that our islands are right in the path of the wind! This is the source of the tradewinds, which blow about 80% of the time in the Kau season.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-ilTeu3pd-zaSILM2HWaTEAZO4ya7Z6S_LWsoBLl39UREydS17v0DRi0DduacRmhl6ets99CAJs3s6Nus6DMITcCHuN8zKuFO_mq3ZWT_aRSNXsY3H_8fOib5f7TeiEf1l3CoK_w0nopB/s1600/sthp_winds_july.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-ilTeu3pd-zaSILM2HWaTEAZO4ya7Z6S_LWsoBLl39UREydS17v0DRi0DduacRmhl6ets99CAJs3s6Nus6DMITcCHuN8zKuFO_mq3ZWT_aRSNXsY3H_8fOib5f7TeiEf1l3CoK_w0nopB/s1600/sthp_winds_july.jpg" height="299" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">July patterns. Approximately location of Hawai'i denoted with red circle. Map from <a href="http://www.goes-r.gov/users/comet/tropical/textbook_2nd_edition/navmenu.php_tab_4_page_2.3.0.htm">here</a>.</td></tr>
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When it is winter in the northern hemisphere it is summer in the southern hemisphere, since the subsolar point and ITCZ shift to the south. Along with this travels the Hadley cells. Another characteristic of the northern hemisphere winter months is that the Hawaiian High tends to weaken, and so the tradewinds are less consistent. At the same time, the storm-producing polar front (another part of the global atmospheric circulation), moves to the south. One major characteristic of the polar front is that it produces low pressure systems that drive cold fronts and produce heavy rainfall and severe weather. These are the same types of systems that generally bring high snowfall totals to the continent in the winter months. Hawaii is much further south (and surrounded by the ocean), so with the exceptions of Mauna Kea, Mauna Loa, and Haleakala we don't get any snow. But a few times a year the cold fronts do sweep down and roll over Kaua'i, Oahu, and the other islands, moving from west to east. <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTtsA2PcmIrYpAKsifUYMxNm0QCSS17oIBhoFpe1TwULVkXuJbEz76q19Tx_R_qSRyxK_zKn_C96341Edd_VcH_L0LM-Sec6LoFc5-1JLKrbpaIx5qVELSKB2UkRL5nWP8BGNpUTOcA0ma/s1600/sthp_winds_jan.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTtsA2PcmIrYpAKsifUYMxNm0QCSS17oIBhoFpe1TwULVkXuJbEz76q19Tx_R_qSRyxK_zKn_C96341Edd_VcH_L0LM-Sec6LoFc5-1JLKrbpaIx5qVELSKB2UkRL5nWP8BGNpUTOcA0ma/s1600/sthp_winds_jan.jpg" height="302" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">January patterns. Red circle approximates Hawai'i's location. Map from <a href="http://www.goes-r.gov/users/comet/tropical/textbook_2nd_edition/navmenu.php_tab_4_page_2.3.0.htm">here</a>.</td></tr>
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When this happens there is a fairly noticeable sequence of atmospheric events that will, if you know what to look for, help you to predict the weather over the next couple of days and amaze your friends. The first thing that will happen is that the wind will start blowing from the south (Kona). This happens because the wind blows roughly parallel to an approaching cold front, heading in the direction of the low pressure area that is at the center of the storm system. The wind will gradually strengthen. You may also notice a very characteristic cloud progression. The first clouds you notice will arrive a day or two ahead of the front (depending on how fast the front is moving). These clouds will be very high (<b>cirrus</b>) clouds and will cover much of the sky. Then as the front continues to move towards your island, you'll see lower and lower (and thicker, more ominous) clouds appear, until finally the sky is socked in by low <b>cumulus </b>clouds. The reason that this happens is that the cold air that is approaching is abruptly pushing up the warmer, moist air in front of it. This causes the air to cool, which leads to cloud formation. <br />
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When the front arrives it will bring with it significant rainfall and pretty heavy winds in some cases. Sometimes the fronts pass quickly, but sometimes they may stick around for a couple of days. After the front passes, you should notice clear skies, and the direction of the wind will shift; instead of coming from the south it will be coming from the west or northwest. Then after a day or two if high pressure conditions return to the north of the islands, the trade winds will return.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPWPDm70XLUnz9WNkZmdabHos5Dhwvea5GqMUptwCTG-6uUnEejeRBYSQmNSEUsSXrPVVeG0rDydmFdEhEZbZ2gsD177m53nHzD2rDMaKWir6n38sX8xar2I8Jx7xdQ3UAVwxdIviZKStY/s1600/OPC_PAC.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPWPDm70XLUnz9WNkZmdabHos5Dhwvea5GqMUptwCTG-6uUnEejeRBYSQmNSEUsSXrPVVeG0rDydmFdEhEZbZ2gsD177m53nHzD2rDMaKWir6n38sX8xar2I8Jx7xdQ3UAVwxdIviZKStY/s1600/OPC_PAC.gif" height="468" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The entire north Pacific at the time this post was written. The symbols point in the direction the wind is blowing. From <a href="http://www.opc.ncep.noaa.gov/">National Weather Service</a>.</td></tr>
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That pretty much sums up winter cold fronts in Hawai'i. These don't happen in the summer time because the polar front, which is the source of the disturbances, moves northward in the summer time. So the next time the wind starts to blow from the south, keep your eyes on the sky, and you may be able to apply what you've learned here and in class. And when you do, you can remember the <i>kilo lani</i>, or "sky watchers", who were special kahunas in Old Hawai'i that had a tremendous amount of knowledge about their natural environment, including the atmospheric conditions and signs that helped them to predict the weather.<br />
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Exercises<br />
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<h3>
Notes </h3>
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(1) To be discussed in a future post<br />
<br />Geografika Nusantarahttp://www.blogger.com/profile/02009398091652720545noreply@blogger.com0tag:blogger.com,1999:blog-5257536511921094573.post-60158922211644848352014-01-11T20:33:00.005-08:002014-01-13T08:43:16.826-08:00How to Outline a Textbook Chapter...<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgiQY4rm-CHsDR0MgzBFjTpoI9giV2PlFwzY8cwLobNxVOaxYa5sCC6I3lVvrDdxTVaWWuEGDvDfZFNiYchQx3NtSp10RCIvVUv73MYW-hpKGaT8Jluat-DuMYoIREZXv3X5bKJ5yBpWblw/s1600/Theodolite_Diamondhead_Sunset_101913+(1).jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgiQY4rm-CHsDR0MgzBFjTpoI9giV2PlFwzY8cwLobNxVOaxYa5sCC6I3lVvrDdxTVaWWuEGDvDfZFNiYchQx3NtSp10RCIvVUv73MYW-hpKGaT8Jluat-DuMYoIREZXv3X5bKJ5yBpWblw/s320/Theodolite_Diamondhead_Sunset_101913+(1).jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Photo by John Delay</td></tr>
</tbody></table>
School is starting up, and that means there's a fresh new crop of young, budding geographers eager to begin learning about way the world works. But besides learning about the way the world works, students should also be working to develop study skills, which will help us not only to do well in class and retain the material that has been covered, but also to organize information and be more effective problem solvers in life in general. One important skill that all students should master is how to outline a textbook chapter.<br />
<br />
Outlining a textbook chapter helps you to distill out the most important concepts and material while organizing it in a way that makes it easy to review. Many students are reluctant to outline chapters because it takes some time, but I promise that in the long run it really pays off, because you won't have to read the chapter again when it is time for an exam, and it will help you to remember the most important and useful points of the chapter. For a standard textbook chapter, it generally takes me between 2-3 hours, but this includes a careful reading of the chapter. It may take you a little longer, or you migth do it a little more quickly than me, but by the end you will have a great understanding of the chapter and you will also know what points are less clear to you so you can ask questions in class.<br />
<br />
The steps to outlining a chapter are pretty simple. Some guides say to read the chapter first, but I always do my outlines while I am reading through the chapter. I think this is a much more efficient and effective method. Some things to remember:<br />
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<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Make a separate heading for each section in the chapter, and pay attention to the nested headings (sub-headings) within the chapter, and follow this pattern of organization in your outline. This helps you keep track of the relationship of the concepts to one another and their relative importance.<br />
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<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Look for the main idea in each section and subsection and include that in your outline. Then add in the facts and details that seem most relevant to you. Sometimes this takes some getting used to, but it is useful to omit trivial points. Always pay attention to the words in <b>bold</b>. I usually define these under separate sub-headings. <br />
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<span class="Apple-tab-span" style="white-space: pre;"> </span>3. Repeat these steps for each chapter in the paragraph.<br />
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Soon you'll have a great, detailed chapter outline that will help you remember what you've read, and you will be able to go over it in a fraction of the time it takes to read the entire chapter. And if you keep your outlines you'll probably find they are useful in other classes, or if you ever have to prepare a literature review or take comprehensive exams. <br />
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Below I've included a sample outline I made of the first chapter of McKnight's Physical Geography, the textbook we use for 101 at Leeward. Use this as an example. Your outlining style may be a little different from mine, but this will give you the basic idea. <br />
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Good luck, and have a great semester!<br />
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<h3>
EXAMPLE CHAPTER OUTLINE</h3>
This outline took me approximately 2.5 hours for a 30 page chapter.<br />
<b><u><br /></u></b>
<b><u>McKnight Chapter 1: Introduction To the Earth</u></b><br />
<br />
<b>I. Introduction</b><br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>A. What do geographers study?<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Tangible things....rainfall, mountains, trees<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Less tangible things...language, migration, voting patterns<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>B. What is this book about<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Fundamental processes in the natural world<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>C. This chapter sets the stage for the study of physical geography<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Important stuff in the chapter<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. using science to explain natural environment<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. the "spheres of the earth"<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>c. Earth's place in the Solar System<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>d. Latitude and Longitude<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>e. What causes the seasons<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>f. Time zones....how do they work?<br />
<br />
<b>II. Geography and Science</b><br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>A. Intro to section<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Geography from Greek meaning Earth Description<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. used to be purely descriptive discipline<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>B. Studying the World Geographically<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Two basic branches<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Physical geography (Environmental)<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Cultural Geography (Human)<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Fundamental question: "Why what is where and so what?" (4)<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. Also interested in interrelationships<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>4. Global Environmental Change....a broad theme of the book<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. both human and natural changes<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. long and short temporal scales<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>5. Globalization...another theme running through the book<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. processes and consequences of an increasingly interconnected world<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>C. The Process of Science<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Scientific method<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Observe phenomena that stimulate a question or problem<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Offer an educated guess about the answer (hypothesis)<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>c. Design an experiment to test the hypothesis<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>d. predict the outcome of the experiment if the hypothesis is supported and if it is not supported<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>e. Conduct the experiment and see what happens<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>f. Draw a conclusion or formulate a simple generalized rule based ont eh results of the experiment. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Science best though of as a process or even an attitude for gaining knowledge<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. New observations and new evidence often cause scientists to revise their conclusions and theories or those of others<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>D. Numbers and Measurement systems<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Two different systems in use<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. English System (US)...miles, pounds, etc<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. International System (pretty much everywhere else). <br />
<br />
<b>III. Environmental Spheres and Earth Systems</b><br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>A. Earth's Environmental Spheres<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Lithosphere....rocks of Earth's crust as well as unconsolidated mineral matter...<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Atmosphere...gaseous envelope of air surrounding the Earth<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. Hydrosphere....comprises water is all its forms....<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Cryosphere, or ice and snow, is part of this<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>4. Biosphere....all parts where living organisms can exists. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>B. Earth Systems<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Definition: a system is a collection of things and processes connected together and operating as a whole (8). <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Closed systems....self contained and isolated from outside inclfluences<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Earth with respect to matter<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Not many other examples<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. Open Systems....inputs and outputs<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. most systems are like this. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>4. Equilibrium...when inputs and outputs are in balance over time<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. If balance changes, equilibrium will be disrupted until a new equilibrium is reached...<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>5. Interconnected Systems...most systems are connected with other systems<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>6. Feedback Loops....some systems produce outputs that feedback into the system, reinforcing change<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Positive feedback loops change the system in one direction<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Negative feedback loops inhibit a system from changing<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>c. tipping points (thresholds) beyond which the system becomes unstable and changes abruptly until it reaches a new equilibrium. <br />
<br />
<b>IV. Earth and the Solar System</b><br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>A. The Solar System<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Earth one of 8 planets<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. lots of other things in the solar system as well<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. Origins....most think the big bang 13.7 billion years ago<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Our solar system 4.5-6 billion years ago from a nebula<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>4. Planets<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Terrestrial...mercury, venus, earth, mars<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>i. smaller, denser, less oblate<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Jovian....Saturn, Uranus, Jupiter, Neptune<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>i. Larger, more massive, more oblate<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>B. The Size and Shape of Earth<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. The Size of Earth<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. topographical maps are usually very exaggerated<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Relief of the earth isn't very great compared to total size.<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. The Shape of Earth<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Almost, but not quite spherical<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Bigger around at equator than through the poles (flattened)<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>c. An "oblate spheroid" (12)<br />
<br />
<b>V. The Geographic Grid--Latitude and Longitude</b><br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>A. The Geographic Grid<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Equator, North Pole, South Pole<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Great circles....any plane that passes though the center of the sphere and divides it into two equal halves<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. this is the largest circle that can be drawn on the sphere<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>i. Creates hemispheres<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. The path between two points on a great circle is always the shortest route (the "great circle route")<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. Small circles are created by planes crossing through other parts of the sphere<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>4. Grid system based on small and great circles.<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>B. Latitude: description of location expressed as an angle north or south of the equator<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Expressed in degrees, minutes, seconds<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Goes from 0-90, N and S<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. Lines connecting all points of same latitude are called parallels.<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. these never cross<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>4. Descriptive zones of latitudes<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. low, midlatitude, high, equatorial, tropical, subtropical, polar<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>5. Nautical miles...the distance covered by one minute of latitude: 1.15 miles. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>C. Longitude: an angular description of location in the east-west direction. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. A line connecting all points of the same longitude is a meridian<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Only parallel to one another when they cross the equator<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. distance between them is not constant. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. Establishing the Prime Meridian<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. problem is that there is no natural baseline for measuring longitude<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Prime Meridian through Greenwich England established by international agreement in 1883. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>4. Measuring Longitude<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Maximum of 180 degrees<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Also uses minutes and seconds<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>c. halfway around the world from the PM is the international datae line. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>D. Locating Points on the Geographic Grid<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Latitude and longitude together can be used to find an exact location<br />
<br />
<b>VI. Earth-Sun Relations and the Seasons</b><br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>A. Earth Movements<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Rotation on the access<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Takes 24 hours (one day) in counterclockwise (from N pole) direction<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. The speed of rotation varies depending on latitude<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>c. Rotation has several important effects<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>i. Coriolis effect: deflection of winds and ocean currents<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>ii. Brings all points through increasing then decreasing gravity of the moon, causing tides<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>iii. Diurnal (daily) alternation of daylight and darkness<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Revolution around the sun<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. 365 days, 5 hours, 48 minutes, and 46 seconds<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Orbit is elliptical and so distance between earth and sun varies<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>i. Perihelion is when we are closest to the sun (January 3)<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>ii. Aphelion is when we are farthest away (July 4)<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. Inclination of the Earth's axis<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. imaginary plane of orbit is called the plane of the ecliptic<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Earth is tilted at 23.5 degrees off a line perpendicular to this plane<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>c. the tilt is always in the same direction throughout the year. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>4. Polarity of the Earth's Axis<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Tilt is always in the same direction (axial parallelism).<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Combined effects of rotation, revolution, inclination and polarity result in seasonal patterns. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>B. The Annual March of Seasons<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Seasonal variation increases in general as you move away from the equator. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Three things really important<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Latitude receiving sun from DIRECTION OVER HEAD (declination of the sun)<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Solar Altitude (height o the sun above the horizone)<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>c. The lengtu of the day. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. June Solstice: About June 21<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. the point in orbit where the north pole is maximum tilted towards sun<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Tropic of Cancer (23.5 N latitude) has sun directly overhead. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>c. Longest day in the northern hemisphere, shortest in southern<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>d. 24 hours of day north of Arctic circle, 24 hours of night south of Antarctic circle<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>4. September Equinox: September 22<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. All locations on earth experience 12 hours of day, 12 hours of night<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>5. December Solstice: Around December 21:<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. The opposite of the June Soltice...<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Sun directly overhead at Tropic of Capricorn (23.5 South)<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>6. March Equinox: March 20<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Same as the September Equinox<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>C. Seasonal Transitions<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Latitude Receiving the Vertical Rays of the Sun...<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. Sun rays only strike vertically between Tropic of Cancer and Tropicc of Capricorn, depending on the time of year<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. analemma is a diagram showingthe latitude of the vertical rays of the sun.<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. Day Length<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. At the equator day length is constant...12 hours<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>b. Day length changes more seasonally the further you get from the equator<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>c. Overall, the annual variation in day length is the least in the tropics and greatest in the high latitudes<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. Day length in Arctic and Antarctic<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. these regions experience 24 hours of daylight and 24 hours of darkness over the course of the year. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>D. Significance of Seasonal patterns<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Both day length and the angle at which the Sun's rays strike Earth determine the amount of solar energy received at any particular latitude<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. The higher the sun is in the sky, the more effective is the warming. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>3. Seasons are basically determined by the amount of sunlight a place gets. <br />
<br />
<b>VII. Telling Time</b><br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>A. Standard Time<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Telegraph and railroad and other technologies increase connectivity creating a need for standard time....<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>2. 24 time zones of 15 degrees longitude agreed to in 1884.<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>B. International Dateline<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. 180th meridian is the international dateline<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. opposite from the prime meridian. <br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>C. Daylight Savings Time<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>1. Created to conserve energy during WWI in Germany<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>a. US begins the policy in 1918. <br />
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Geografika Nusantarahttp://www.blogger.com/profile/02009398091652720545noreply@blogger.com0tag:blogger.com,1999:blog-5257536511921094573.post-34142197367428375002013-06-30T18:41:00.001-07:002013-06-30T18:41:55.100-07:00Things to Know About Albedo...<div class="separator" style="clear: both; text-align: center;">
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<tr><td style="text-align: center;"><a href="http://4.bp.blogspot.com/-xN3y7mXrZGQ/UdDSsUY4VOI/AAAAAAAACKo/qRGhGZmbWyU/s1600/IMG_5646.JPG" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="300" src="http://4.bp.blogspot.com/-xN3y7mXrZGQ/UdDSsUY4VOI/AAAAAAAACKo/qRGhGZmbWyU/s400/IMG_5646.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Which side of the T&C logo is hotter: the white side or the black? Does<br />it matter? For the answer see the end of this blog post. </td></tr>
</tbody></table>
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Have you ever heard that it is cooler to wear lighter
clothes on a hot, sunny day? How could
this be? How could the color of
your clothes make a difference in temperature?
This couldn't possibly be true, could it? Well, it is true, and the difference in
temperature is explained by <i>albedo</i>.
<b>Albedo </b>refers to the proportion of the sun's energy (<i>insolation</i>) that is
reflected by a surface. Albedo is
generally expressed as a percentage, and so if it is high (say, 90%), then more
of the sun's energy is being reflected by a surface. The 90% figure means that 90% of the sun's energy is reflected off the surface. If albedo is low (10% for example) then more
of the sun's energy is absorbed. In this case, only 10% of the sun's energy is reflected whereas the balance is absorbed. If a
surface absorbs more energy, it heats up more.
We can change the albedo of a surface simply by changing its color;
light colored surfaces tend to have higher albedo than darker surfaces. One very good example of this is clothing; on
a sunny day here in <st1:state w:st="on">Hawai'i</st1:state>
white shirts can be as much as 30 degrees cooler than dark shirts. In this post we'll be looking at another
practical example of the difference that albedo can make.</div>
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<h2>
A White Roof?</h2>
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One of the neat things about studying physical geography is
that we can see practical applications of what we learn everywhere. A couple of years ago the property managers of the apartment complex that houses one of this blog's authors installed a "white roof", coating the roof of the building with a white polymer that significantly increased the roof's albedo. In other words, the white roof reflected a great deal more energy than the old tar roof. Immediately after the white roof was installed we noticed a big change
in the temperature of the apartment....it was a lot cooler! Even on the hottest days of the year at the
peak of the afternoon sun we no longer needed to run the air conditioner to
stay comfortable. The new roof made a
big difference and has saved us money on our electric bill, which in turn leads
to decreased greenhouse gas emissions. In
short, everyone wins. </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBhfALdYDqJm2G5X44UynnfOBaHl-U9e-UEEiQyizpCnBJ0Xv8FU7t-Adg1IMJ9pkXrCdEw_eor7UzSX77KkU_jM3mIw-IwtAYIcrmXUfdKyGJviCWLWWu2i1QNJ3heB4i6mVdD5KVzGm5/s1600/IMG_5643.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBhfALdYDqJm2G5X44UynnfOBaHl-U9e-UEEiQyizpCnBJ0Xv8FU7t-Adg1IMJ9pkXrCdEw_eor7UzSX77KkU_jM3mIw-IwtAYIcrmXUfdKyGJviCWLWWu2i1QNJ3heB4i6mVdD5KVzGm5/s320/IMG_5643.JPG" width="240" /></a></div>
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More recently the management company had the entire building
repainted, which was long overdue. The
old color was pale pink, a very light color.
The new color is dark gray. Based
on our experience with the white roof, I was perplexed as to why the management
company would go with a dark color, because I reasoned that the darker color would absorb more of the sun's energy, thus making the interior of the building slightly warmer. I
was also curious how much a difference the darker color made to the surface temperature of the building. So we here at TWITB decided to do an informal investigation: we would measure the temperature using an ExTech infrared thermometer, a handy little tool which uses a laser to measure surface temperatures. We measured the temperature at approximately 3:20pm, which is approximately the hottest time during the day in Honolulu (why this is the case will be covered in a future post). Since the painters didn't quite finish the job on the first day there was still some of the old pink surface (see the photo to the left), and so we could compare the results. We measured the pink surface, the grey surface, and the dark gray doors. We measured them in the sun and in the shade as well. Which one do you think we found to be the hottest?</div>
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We were really amazed with what we found. First the pink paint in the shade was 98 degrees whereas in the sun it was 110. The concrete bricks that had been painted gray were 103 degrees in the shade and 130 in the sun. The door was most surprising; in the shade it measured 111 degrees, whereas in the sun it measured 148 degrees. So as you can see the paint really makes a big difference! Whether this affects the interior temperature is a more complex problem to solve; this depends on the specific heat and conductive properties of the bricks and the door. </div>
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So as you can see the color of a surface definitely does make a difference in surface temperature. Let's look at some more examples. In the picture below you will see some cars in a parking lot. We've placed letters over a few surfaces. This picture was taken at 3:30pm on a day when the official airport temperature was measured at 88 degrees. "A" is exposed blacktop. "B" is a white car in full sun. "C" is a white parking space marker painted on the exposed blacktop. "D" is shaded leaves. "E" is a black car in full exposure to the sun, and "F" is a green car in full exposure. "G" is blacktop in the shade. For reference, we also measured a grass patch (not pictured) in the sun; its temperature was 110 degrees. Match the letters from the picture with the numbers below the picture that correspond to the temperatures of each surface. </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdueHO7w-3A98fwVC8NghQqfFJQaPqGZj_wRwBd1ab9uW-YV7QI9ScR2GftbVeNi1LUnF8aYdcR9zXDsjNW26LCTzjauCvpW5U3ApbZl7-prCvE472CwbHmDLPyjmjPzeSurJUpOuuDp1W/s472/ALBEDO+PIC.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdueHO7w-3A98fwVC8NghQqfFJQaPqGZj_wRwBd1ab9uW-YV7QI9ScR2GftbVeNi1LUnF8aYdcR9zXDsjNW26LCTzjauCvpW5U3ApbZl7-prCvE472CwbHmDLPyjmjPzeSurJUpOuuDp1W/s640/ALBEDO+PIC.jpg" width="520" /></a></div>
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1. 164 degrees.</div>
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2. 91 degrees.</div>
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3. 143 degrees.</div>
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4. 117 degrees. </div>
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5. 114 degrees.</div>
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6. 151 degrees.</div>
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7. 138 degrees.</div>
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You can do similar tests yourself just by touching various surfaces on a hot day. You'll also notice a big difference between the shade and exposed temperatures for the same surface. In a future post we'll explain more in depth why color makes a big difference, but for now it's enough to know that darker things are hotter and lighter things are cooler. As for the T&C logo, check out the pictures below.</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijMtImFtjYMvdyFZ_UfNhPvKMLo9v5G3WexeFSpiHfDdot0-yzL68fEhigiD0m_IdQjPkZmF-rYm6D_Imd4J8EqCagF7NQ4nc-G9oDX-aWETMlFA-a5ylrJCnL2qotns17N9qWOnKDowr5/s1600/IMG_5648.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijMtImFtjYMvdyFZ_UfNhPvKMLo9v5G3WexeFSpiHfDdot0-yzL68fEhigiD0m_IdQjPkZmF-rYm6D_Imd4J8EqCagF7NQ4nc-G9oDX-aWETMlFA-a5ylrJCnL2qotns17N9qWOnKDowr5/s640/IMG_5648.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">White side.</td></tr>
</tbody></table>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig7_Jet-f7TKFpMCZSbex4hiwqRPUlSlw9tpWhyphenhyphenXV2PwWha-kvSBFFYTRcagRhAUb3Ha3Hjc5stEVxfwX3rP-YniF5uEMRqvm3Br2XhctZxMk-uqicRdznlNgkt5vXh8zlfk_-Vp1667Dx/s1600/IMG_5649.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="480" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig7_Jet-f7TKFpMCZSbex4hiwqRPUlSlw9tpWhyphenhyphenXV2PwWha-kvSBFFYTRcagRhAUb3Ha3Hjc5stEVxfwX3rP-YniF5uEMRqvm3Br2XhctZxMk-uqicRdznlNgkt5vXh8zlfk_-Vp1667Dx/s640/IMG_5649.JPG" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Black side.</td></tr>
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Answers: 1. E 2. D 3. F 4. B 5. G 6. A 7. C </div>
Geografika Nusantarahttp://www.blogger.com/profile/02009398091652720545noreply@blogger.com0tag:blogger.com,1999:blog-5257536511921094573.post-65276551073679852492013-06-21T23:10:00.000-07:002013-07-05T12:59:14.146-07:00The Solstice is Upon Us!<div class="MsoNormal">
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4CZtiY2am7FfT6JGFPKXhEqkdG4grTtpoWESk8EkA-tY3ZdqTTUmR88fm8SWZj8W261HogLsquNVK-90GQxpgz2t9H4Ikd4LgsibrePOBNkFBeCjHSmnaT6S0YwkLKv_FEEGNfqTvDocb/s1600/SummerSolsticeStonehenge.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4CZtiY2am7FfT6JGFPKXhEqkdG4grTtpoWESk8EkA-tY3ZdqTTUmR88fm8SWZj8W261HogLsquNVK-90GQxpgz2t9H4Ikd4LgsibrePOBNkFBeCjHSmnaT6S0YwkLKv_FEEGNfqTvDocb/s200/SummerSolsticeStonehenge.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Photo from <a href="http://www.transcend.ws/summer-solstice-on-wednesday-june-20/">here</a>.</td></tr>
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Today is June 21st, the longest day of the year in <st1:state w:st="on">Hawai'i</st1:state>. Today the sun came up at 5.50am and will set
at 7.16pm, for a total day length of 13 hours, 25 minutes, and 54 seconds. We call this day the <i>June</i> (or Summer)
<i>Solstice</i>. After today the days will
continue to get shorter until December 21st, with a day length of 10 hours, 50
minutes, and 12 seconds. December 21st
is the <i>December </i>(or Winter) <i>Solstice</i>. In
this post we will describe why there is variation in day length over the course
of the year.</div>
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<h2>
<b>The Earth-Sun
Relationship...</b></h2>
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As we all know, the Earth revolves around the sun, a journey
that takes approximately 365.22 days. We
also know that the earth is tilted on its axis at an angle of approximately
23.5 degrees. This is why virtually
every globe you ever see is tilted; it is demonstrating the earth's true
orientation towards the sun. But did you
know that the tilt is always in the same direction? This characteristic of the earth's orbit is
called<i><b> axial parallelism</b></i>, and it is why days are shorter in the winter and
longer in the summer. This in turn is
one of the biggest factors in seasonal variability; it is why the continental <st1:country-region w:st="on">United States</st1:country-region>
experiences winter, spring, summer, and fall. <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidHWVNLU2M6uuBWoBJzf5Cl15gZnNXwgjUtHxdN2-w1iGqd8wlDGH3fGvGac43DbgcLD5nRth0ohzGPWHdkgg7YU8h6HiMtOPCDWVJfruntOjb33rBC7HHC8w0SW_gCw8UYGNTM_qYO4tZ/s1600/Earth+Sun+Relationship.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="408" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidHWVNLU2M6uuBWoBJzf5Cl15gZnNXwgjUtHxdN2-w1iGqd8wlDGH3fGvGac43DbgcLD5nRth0ohzGPWHdkgg7YU8h6HiMtOPCDWVJfruntOjb33rBC7HHC8w0SW_gCw8UYGNTM_qYO4tZ/s640/Earth+Sun+Relationship.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Diagram from <a href="http://www.sonoma.edu/users/f/freidel/global/207lec1images.htm">here</a>. </td></tr>
</tbody></table>
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Have a look at the model we've provided. As you can see, no matter what time of year
it is, the earth's tilt is in the same direction. If it is December, then more of the southern
hemisphere is exposed to the sun at any given time, and less of the northern is
bathed in glory of the sun's warming touch. It follows then that in December it is summer
in the southern hemisphere, and winter in the northern hemisphere. If you imagine with your mind's eye that the
earth is spinning around its axis (remember, one rotation equals one day), you
can see that since more of the southern hemisphere is in the sun, the days are
longer. The opposite is true with the
northern hemisphere. Now look at the
earth when it is June and the planet's northern hemisphere is at its maximum
tilt towards the sun. Can you see that
more of the northern hemisphere is exposed to the sun, whereas less of the
hemisphere is? Thus the days are no
longer in the northern hemisphere than in the southern. Now look at the north pole. Again, imagine with your mind's eye that the
earth is spinning on its axis. Look at
the places close to the north pole. Is
there ever a point during a day (one complete rotation) that these points enter
the darkness? If you answered
"no" you are correct! These
areas experience 24 hour days at this point, whereas at the south pole and near
it there are 24 hour nights!</div>
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So at this point it should make sense to you that there is
one day during the year when the northern hemisphere is at its maximum tilt
towards the sun (whereas the southern hemisphere is a it maximum point away
from the sun), and another point, roughly half a year later where the northern
hemisphere is at its maximum tilt away from the sun (whereas at this point the southern
hemisphere would be pointed towards the sun). These two days are called the <i><b>solstices</b></i>, and
they are the longest and shortest days of the year respectively in the northern
hemisphere (and the opposite in the southern hemisphere). </div>
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Now look back at the diagram. There are two days of the year, one in March
and the other in September, where the earth is pointed neither towards nor away
from the sun; rather the tilt of the earth is perpendicular to a line drawn
from the sun to the earth. On these days
every part of the earth receives 12 hours of daylight and 12 hours of night. These days are called <i><b>equinoxes</b></i>.<br />
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<h2>
So What Are the Tropics?</h2>
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We've all heard the term "<i>tropics</i>", as in tropical
storm, tropical paradise, and tropical fish.
But what does this really mean?
The "<i>tropics</i>" describes a very specific area on the earth's
surface: all latitudes where the sun passes directly overhead at some point
during the year. Let's go back to our
diagram of the earth-sun relationship.
Since the earth is rounded, there is a point on the earth's surface that
is closer to the sun than all other points.
If you were standing on that point, the sun would be directly
overhead. Now since the earth is tilted,
the spot on the earth where the sun is directly overhead changes over the
course of the year. The spot where the
sun is currently overhead is called the <i><b>subsolar point</b></i>, and the latitude where
the sun is directly overhead is called the <b><i>solar declination</i></b>. Since the earth is tilted at an angle of 23.5
degrees, the subsolar point is found between 23.5 north latitude (the <b><i>Tropic of
Cancer</i></b>) and 23.5 south latitude (the <b><i>Tropic of Capricorn</i></b>). The area between these two lines of latitude
is the tropics, and as we all know, <st1:state w:st="on">Hawai'i</st1:state>
is in the tropics. This means that the
sun will be directly overhead at solar noon in <st1:state w:st="on">Hawai'i</st1:state> on two days during the year, one in
May, and one in July. Any place outside
the tropics never ever experiences the sun directly overhead! This is one more aspect of <st1:state w:st="on">Hawai'i</st1:state>'s geography that makes it
special. </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiBGLnIUWULF1A7NNT1Vo5lvy_HNUeNCjGbnPLJUJ-J6NcrO4rhLWSQOWQ0gbYNTtt2FEnbhrqAATdQZqNmPmY-MP4_2iXMOuavhP9tsXZbxzYEcfbE3jb98c9PAdsJ4gBIbDKYBNDWU8m1/s1600/Tropics+diagram.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="496" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiBGLnIUWULF1A7NNT1Vo5lvy_HNUeNCjGbnPLJUJ-J6NcrO4rhLWSQOWQ0gbYNTtt2FEnbhrqAATdQZqNmPmY-MP4_2iXMOuavhP9tsXZbxzYEcfbE3jb98c9PAdsJ4gBIbDKYBNDWU8m1/s640/Tropics+diagram.jpg" width="640" /></a></div>
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<h2>
Lahaina Noon?</h2>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEisn_Q0iyMnykOF5uS1A8uGsBDBwMNLQiiKd5z-Gm8PAI3fkSIdMrKbI1lWYx3dzrvHRQ4M0ndS7pJZPMWea5dmq9YtVpcZMwmwR4wV3Ily97a6xwAD_ngEzKNOWl9WRnhooRo7uO-_Dj6o/s1600/SkyGate.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="323" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEisn_Q0iyMnykOF5uS1A8uGsBDBwMNLQiiKd5z-Gm8PAI3fkSIdMrKbI1lWYx3dzrvHRQ4M0ndS7pJZPMWea5dmq9YtVpcZMwmwR4wV3Ily97a6xwAD_ngEzKNOWl9WRnhooRo7uO-_Dj6o/s400/SkyGate.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Honolulu SkyGate at Lahaina Noon. Photo from <a href="http://www.hawaiihealthguide.com/healthtalk/display.htm?id=922">here</a>. </td></tr>
</tbody></table>
If you've ever been to <st1:place w:st="on">Maui</st1:place>
(or if you live there!) you may have visited Lahaina. Lahaina is a major tourist attraction and is known as an old capital of the Hawaiian kingdom. But Lahaina also gives its name to the day when the sun is directly overhead at solar noon in <st1:state w:st="on">Hawai'i</st1:state>.
We call this "<b>Lahaina Noon</b>".
This name was immortalized in a contest sponsored by the <st1:place w:st="on"><st1:placename w:st="on">Bishop</st1:placename> <st1:placetype w:st="on">Museum</st1:placetype></st1:place>.
"<b><i>Lahaina Noon</i></b>" was chosen for
these two days when the sun is at its greatest intensity because La Haina means
"cruel sun" in Hawaiian. On
this day at solar noon you can witness something that no one on the continent
ever sees (at least on clear days): a complete lack of shadows. Since the <st1:place w:st="on">Hawaiian
Islands</st1:place> run to the northwest, Lahaina Noon happens on different
days at different places. In the table
below you can see the dates for this year (2013); the <st1:place w:st="on"><st1:placename w:st="on">Bishop</st1:placename> <st1:placetype w:st="on">Museum</st1:placetype></st1:place>
normally provides the dates on their website as well. <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZX12PrPUz1Owl8Rrhf5BIiLAXJDGpnvq7UGK3WJ3F-JT7E4JenA626hkv0JD2Vvc4n0TMnsF_FjVy_hRgUTeGNwt97Cdg9OFEiQsZ5oQnoMC4ihklR-UVJkTTV22r9wDZWUJXIT8ip5MP/s1600/Lahaina+Noon+Dates.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZX12PrPUz1Owl8Rrhf5BIiLAXJDGpnvq7UGK3WJ3F-JT7E4JenA626hkv0JD2Vvc4n0TMnsF_FjVy_hRgUTeGNwt97Cdg9OFEiQsZ5oQnoMC4ihklR-UVJkTTV22r9wDZWUJXIT8ip5MP/s640/Lahaina+Noon+Dates.jpg" width="600" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Information from the <a href="http://www.bishopmuseum.org/planetarium/highlights2013.html#ln">Bishop Museum</a>.</td></tr>
</tbody></table>
<br />
<br />
<h2>
Kau Ka La I Ka Lolo</h2>
<br />
<div class="MsoNormal">
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7OUpmkMAvjcn_gEE_oz3Uf5GNmMhKZ2yuUtYzk47_oO-qIvLm5_j47HT-4_wkHoqXrOeUc13ICGNcXV4F3RyniMOqAiyq6YUoV0P9lljIEzRe1FHKqPWVm595EHYAAQH3Xw-S7D088rfi/s1600/map+of+NW+HI.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="270" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7OUpmkMAvjcn_gEE_oz3Uf5GNmMhKZ2yuUtYzk47_oO-qIvLm5_j47HT-4_wkHoqXrOeUc13ICGNcXV4F3RyniMOqAiyq6YUoV0P9lljIEzRe1FHKqPWVm595EHYAAQH3Xw-S7D088rfi/s400/map+of+NW+HI.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Map from <a href="http://sanctuaries.noaa.gov/science/condition/pmnm/history.html">NOAA</a>. </td></tr>
</tbody></table>
The old Hawaiians were very attuned to the movement of celestial bodies (the sun, stars, and the moon) and referred to the day when the sun was directly overhead as <i>kau ka la i ka lolo</i>. This expression can be translated as "the sun rests on
the brains". We understand now that these days had special significance to the old Hawaiians as well. Based on research by University of Hawai'i Department of Anthropology graduate Dr. Kekuewa Kikiloi we have learned that many of the archaeological remains on Mokumanamana Island (generally known as Necker Island, one of the Northwest Hawaiian Islands) are tied to rituals associated with the passing of the sun directly overhead. Mokumanamana happens to be right on the Tropic of Cancer, and so the sun is directly overhead here. The Old Hawaiians were keenly aware of this fact, and so the island had a priestly significance to them; high-ranking priests would make periodic journeys to Mokumanamana to calibrate their calendars and for other ceremonies. <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhNd_uD3hXGDs7XJDMF1Mrs3ah1vc7IixG6oyjf9V9Ks9yrPNDaBMtIMSTUHDoXv2Q_aRw0ZlDy454TD7xbQBqzePN9kn_htPJGJe3ry9nl_-gt-1_6NXQsPYTU1NHC2K55Py8_q8YLTYV/s1600/Necker_landsat.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="580" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhNd_uD3hXGDs7XJDMF1Mrs3ah1vc7IixG6oyjf9V9Ks9yrPNDaBMtIMSTUHDoXv2Q_aRw0ZlDy454TD7xbQBqzePN9kn_htPJGJe3ry9nl_-gt-1_6NXQsPYTU1NHC2K55Py8_q8YLTYV/s640/Necker_landsat.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Necker island landsat image from <a href="http://www.papahanaumokuakea.gov/visit/moku.html">Papahanaumokuakea National Monument website</a>. </td></tr>
</tbody></table>
<br />
<br />
<h2>
Exercises:</h2>
<br />
<div style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 12.727272033691406px;">
Will the islands receive more energy from the sun on there respective Lahaina days or on the June Solstice? </div>
<div style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 12.727272033691406px;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 12.727272033691406px;">
What compass direction will the Sun be oriented at solar <span class="aBn" data-term="goog_32304426" style="border-bottom-color: rgb(204, 204, 204); border-bottom-style: dashed; border-bottom-width: 1px; position: relative; top: -2px; z-index: 0;" tabindex="0"><span class="aQJ" style="position: relative; top: 2px; z-index: -1;">noon</span></span> on the days following the first Lahaina <span class="aBn" data-term="goog_32304427" style="border-bottom-color: rgb(204, 204, 204); border-bottom-style: dashed; border-bottom-width: 1px; position: relative; top: -2px; z-index: 0;" tabindex="0"><span class="aQJ" style="position: relative; top: 2px; z-index: -1;">noon</span></span> day? </div>
<div style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 12.727272033691406px;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 12.727272033691406px;">
Why are there two Lahaina <span class="aBn" data-term="goog_32304428" style="border-bottom-color: rgb(204, 204, 204); border-bottom-style: dashed; border-bottom-width: 1px; position: relative; top: -2px; z-index: 0;" tabindex="0"><span class="aQJ" style="position: relative; top: 2px; z-index: -1;">noon</span></span> days for all of the Islands South of Mokumanamana (Necker) island?</div>
<div style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 12.727272033691406px;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 12.727272033691406px;">
Have the islands located north of Mokumanamana ever experienced the Lahaina <span class="aBn" data-term="goog_32304429" style="border-bottom-color: rgb(204, 204, 204); border-bottom-style: dashed; border-bottom-width: 1px; position: relative; top: -2px; z-index: 0;" tabindex="0"><span class="aQJ" style="position: relative; top: 2px; z-index: -1;">noon</span></span> sun?</div>
</div>
</div>
</div>
Geografika Nusantarahttp://www.blogger.com/profile/02009398091652720545noreply@blogger.com0tag:blogger.com,1999:blog-5257536511921094573.post-47041363902496202732013-06-08T14:20:00.000-07:002013-06-08T14:20:15.162-07:00A Trip up Ka'ala 2: Climate and Altitude in Hawai'iIn our last post we described a recent trip we took up to the top of Mt. Ka'ala, the highest mountain on the island of Oahu, topping out at just over 4000 feet. We described how the temperature changes with the altitude, decreasing the higher you get. We discussed the rate at which this happens, which is described as the <i>adiabatic lapse rate</i>. We also discussed <i>humidity</i> and how atmospheric moisture content affects this cooling rate. All of this helped us understand the basic pattern of rainfall on the Hawaiian islands. In this post one of the geography crew will describe how climate, which is determined by temperature and moisture, changes with altitude here in Hawai'i. He'll also tell us about how these different zones are associated with vegetation. <br />
<br />
<h2>
Climate Zones</h2>
<br />
Have you ever wondered why clouds<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsYi27OcSDJn-V6kU9EEA2DRzMKIvZXMREa2YddxOf_AiaRxRlf5L2X3QjsTlvGHdRWKp_WuaBm10ACBwjUgbh-YrUbm2THjcQ_3sHTRrSHYY-k01ORtGnbGyvf5_f4epA6aSxkKm23DmN/s1600/KoppenClass2.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="288" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsYi27OcSDJn-V6kU9EEA2DRzMKIvZXMREa2YddxOf_AiaRxRlf5L2X3QjsTlvGHdRWKp_WuaBm10ACBwjUgbh-YrUbm2THjcQ_3sHTRrSHYY-k01ORtGnbGyvf5_f4epA6aSxkKm23DmN/s320/KoppenClass2.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Koppen chart from <a href="http://www.fas.org/irp/imint/docs/rst/Sect14/Sect14_1d.html">here</a>. </td></tr>
</tbody></table>
form high on the mountain slopes and not at the mountain base, or why there is a dramatic change in plant species as you move upslope? A lot of this has to do with the distinct <b>climate </b>characteristics found in the islands. Four of the five major climate zones described in the <b>Köppen </b>climate classification system can be found in the Hawaiian Islands and within these zones there exists a host of distinct microclimatic sub-zones determined by <b>temperature </b>and <b>precipitation </b>characteristics. The differences in microclimates and the associated vegetation that can be found within these microclimates can be attributed to the vertical profile of the atmosphere. As you increase in elevation you decrease in temperature at a specific lapse rate depending on your environment and this temperature profile dictates the phase change of water in the atmosphere.<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0yLorj7wyfoancMKNUBHFiivL0EhTZjU7e2z8Zbo3DOZQgjLVIHhPptFixaTK-gGSwuEiOYqNDg0mcM4F0myolgYlqC1Z468OySIAb7I3NyEacyxQIjWVbLJiKjmkgqZwaD7EdjgyckEm/s1600/cloud+altitude.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="283" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0yLorj7wyfoancMKNUBHFiivL0EhTZjU7e2z8Zbo3DOZQgjLVIHhPptFixaTK-gGSwuEiOYqNDg0mcM4F0myolgYlqC1Z468OySIAb7I3NyEacyxQIjWVbLJiKjmkgqZwaD7EdjgyckEm/s320/cloud+altitude.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Diagram from <a href="http://meteora.ucsd.edu/~mpritchard/bib/BrePar08/index.html">here</a>.</td></tr>
</tbody></table>
<span style="font-family: Calibri; font-size: 11.0pt; line-height: 115%; mso-ansi-language: EN-US; mso-bidi-font-family: "Times New Roman"; mso-bidi-language: AR-SA; mso-fareast-font-family: Calibri; mso-fareast-language: EN-US;">Climatic
zones on mountain slopes in Hawai‘i can
be characterized with reference to 4 atmospheric layers described by Riehl et
al., (1951). These 4 climate zones with
the corresponding atmospheric layers in parentheses are: 1) <i>marine </i>(subcloud),
2) <i>fog </i>(cloud), 3)<b> </b><i>transitional</i>
(inversion), and 4) <i>arid </i>(free
atmosphere). The <b>sub cloud layer</b> extends from sea level to the lifting condensation
level ( LCL, 600 - 800 m) at which point clouds begin to develop. In a simpler explanation the LCL is the
point at which a warm moist air mass needs to be lifted so it sufficiently
cools to the point at which water makes the phase change from a gas to a liquid
(condensation). The<b> cloud layer</b> exists from the LCL to the base of the Trade Wind
Inversion (TWI) which can lie anywhere between 1000 and 4000 m (Cao et al.,
2007). The TWI is a synoptic subsidence
of warm air that was originally uplifted at the equator by convective and
convergent processes. The TWI, which is
present 80-90% of the year (Cao et al., 2007), has a profound impact on the
climate at high elevations The thickness
of the <b>inversion layer</b> is about ~300
m and above this point the stable dry air of the <b>free atmosphere layer</b> can be found.
The height and thickness of each of these atmospheric layers vary in
space and time in response to large-scale circulation features and surface
heating (Giambelluca and Nullet, 1991).
This layered system exists only in the presence of the trade winds and
disappears when cyclonic systems interrupt them.</span><br />
<span style="font-family: Calibri; font-size: 11.0pt; line-height: 115%; mso-ansi-language: EN-US; mso-bidi-font-family: "Times New Roman"; mso-bidi-language: AR-SA; mso-fareast-font-family: Calibri; mso-fareast-language: EN-US;"><br /></span>
<span style="font-family: Calibri; font-size: 11.0pt; line-height: 115%; mso-ansi-language: EN-US; mso-bidi-font-family: "Times New Roman"; mso-bidi-language: AR-SA; mso-fareast-font-family: Calibri; mso-fareast-language: EN-US;">The
vegetation characteristics across elevation gradients in Hawai‘i are dependent
on several factors, including, <b>substrate</b>, <b>topography</b>, <b>precipitation</b>, available
<b>genotypes </b>and the fragmentation and severe modification of native vegetation,
especially at lower elevations (Mederios, 1986). On hike up the mountain we were able to
experience lower two climate zones mentioned above and the distinct vegetation associated with
these zones. </span><span style="font-family: Calibri;"><span style="font-size: 15px; line-height: 17px;">Three basic ecosystem types occur between the leeward coast and the summit of Mt. Ka‘ala. These can be distinguished by rainfall, elevation, and vegetation type. Lowland dry shrubland and grassland occurs at the lowest elevations although introduced trees are also present. Lowland dry and mesic forest, woodland and shrubland occurs further inland. At higher elevations wet forest and woodland can be found. A special type of ecosystem called tropical montane cloud forest (TMCF) occurs in the summit region and harbors many rare natives species. The ecosystems at lower elevations are dominated by introduced vegetation as a result of disturbance. Native vegetation becomes more dominant the farther one moves up the mountain. The vegetation at lower elevations in the Waianae range area of Mt Kaala is dominated by introduced tree species. Near the coast kiawe (Prosopis pallida) is frequent. Moving inland, koa haole (Leuceana leucocephala) becomes a dominant species. Along the first part of the trail to Mt Kaala itself both species can be seen. Larger silk oak trees (Grevillia robusta) can also be seen. Coffee trees (Cofea Arabica) can also be seen. Moving up the steep slope rainfall increases and disturbance decreases. Native tree species like koa (Acacia koa) and ohia (Metrosideros polymorpha) become common. The last leg of the trail moves into the cloud zone and ohia becomes the dominant tree. Olapa or lapalapa Cheirodendendron trigynum or platyphyllum) becomes more frequent. Olomea (perrotetia sanwicense) is also present. These are the dominant trees in the mosaic and bog at the summit. Also very frequent shrubs include pukiawe (Leptocophylla tameiameia). Rare plants like kolii (tremotlobelia macrostachyus are also present.</span></span><br />
<span style="font-family: Calibri;"><span style="font-size: 15px; line-height: 17px;"><br /></span></span>
<br />
<h2>
<span style="font-family: Calibri;"><span style="font-size: 15px; line-height: 17px;">References</span></span></h2>
<br />
<div>
<br />
Cao, G. G., T. W. Giambelluca, D. E. Stevens, and T. A. Schroeder (2007), Inversion Variability in the Hawaiian Trade Wind Regime. J. Climate, 20, 1145–1160, doi: 10.1175/JCLI4033.1<br />
<br />
Giambelluca, T.W. and Nullet, D. (1991) Influence of the trade-wind inversion on the climate of a leewared mountain slope in Hawai‘i , Clim Res., 1, 207-216</div>
<div>
<br /></div>
Geografika Nusantarahttp://www.blogger.com/profile/02009398091652720545noreply@blogger.com0tag:blogger.com,1999:blog-5257536511921094573.post-13822526527149401302013-05-25T01:40:00.001-07:002013-06-08T13:53:24.401-07:00A Trip Up Ka'ala 1: The Adiabatic Lapse Rate<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCrRBCkAFamCS73ZNySewtjCcND_Z-55yyQ5Iqs2XVnDymCVO_PswvTF8tiR4W73UdxgQDDZV2SIEM1Efci_mxH1-aiNCz_yLxsA5nNwY0YPzwfKuTyANweph-CgY0onlfuDfcF5SUb2Zo/s1600/Intro+Picture.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="298" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCrRBCkAFamCS73ZNySewtjCcND_Z-55yyQ5Iqs2XVnDymCVO_PswvTF8tiR4W73UdxgQDDZV2SIEM1Efci_mxH1-aiNCz_yLxsA5nNwY0YPzwfKuTyANweph-CgY0onlfuDfcF5SUb2Zo/s400/Intro+Picture.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Photo by Wendy Miles</td></tr>
</tbody></table>
One thing you may have noticed here in Hawai'i is that the windward sides of the islands are generally much wetter than the drier sides andf that the mountains towards the interiors of the islands are often cloaked in clouds. For example, it may be bone dry in Honolulu when you get in your car to head up to Kailua or Kaneohe, but as you make your way through the back of Nu'uanu or Kalihi valleys you will likely encounter rain. Then when you come out of the tunnel and drive down towards the beach, the rain starts to lessen and eventually you leave the clouds behind to enjoy your day at the Mokes or the Sandbar. What explains this interesting weather pattern? This first post in a series of three describing our recent trip up Mount Ka'ala, the highest point on Oahu (in the Waianae Range) aims to shed some light on issue.<br />
<br />
<h2>
The Problem...</h2>
<br />
Ah, the adiabatic lapse rate problem. <br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEinvg_GS_AgPNF_StIPRUmWVKOSknvVMS9wYIwpbmzpd_PmcvzlyzfZ_CNW-7DzNRUWksgdaoh0Vzf9NQ3XHoBGMsQnx9d0G71ctvTypJvWFMiIekpY7p_h6z7oxZHOUPl1MrwY-jjTBsUP/s1600/lapse+rate+problem.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="178" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEinvg_GS_AgPNF_StIPRUmWVKOSknvVMS9wYIwpbmzpd_PmcvzlyzfZ_CNW-7DzNRUWksgdaoh0Vzf9NQ3XHoBGMsQnx9d0G71ctvTypJvWFMiIekpY7p_h6z7oxZHOUPl1MrwY-jjTBsUP/s400/lapse+rate+problem.jpg" width="400" /></a></div>
If you've ever taken Geography 101 or the lab (or are currently taking them) at one of the UH system campuses, chances are you've seen this diagram. The scenario is as follows: the wind blows from the northwest (1) into Hanalei Bay on the windward side. The wind forces air up over Mt. Wai'ale'ale, which is one of the wettest places on the planet, and then it comes back down again in Waimea Bay, which is very dry, generally warmer than Hanalei Bay. We see the same basic phenomenon on Oahu, Maui, and the Big Island as well. To figure out why this happens, there are a couple of basic things we need to understand. <br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0RLYWsAxzRUpEblt97rFblYQMyVc7ebiEqvAj_byrs_bgM_ScCz6UHjYW_j2bkmP2i-ccKT_5cxJp7AXUZRmMNIvn2LZGqndwYIT4XSreYVJ4y4c2IiGMJ293mRPxs9_-ziAScw_neCFV/s1600/kauai+map+modified.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0RLYWsAxzRUpEblt97rFblYQMyVc7ebiEqvAj_byrs_bgM_ScCz6UHjYW_j2bkmP2i-ccKT_5cxJp7AXUZRmMNIvn2LZGqndwYIT4XSreYVJ4y4c2IiGMJ293mRPxs9_-ziAScw_neCFV/s640/kauai+map+modified.jpg" width="640" /></a></div>
<br />
<br />
<h2>
The Tradewinds</h2>
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5KuvJVvZBEV2LeLjIp8JK5hyPydSfIEqgKLzJhOek5QGL5LZhaDFmwQ7z_cDIA8SUJ6IyHVaUFY9BtRQuxArFMKUoNcBSQMFP73A2X6-gWLVpT84We87FPHAawfMAdB493C9L3RSIn6P2/s1600/trades+map.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="245" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5KuvJVvZBEV2LeLjIp8JK5hyPydSfIEqgKLzJhOek5QGL5LZhaDFmwQ7z_cDIA8SUJ6IyHVaUFY9BtRQuxArFMKUoNcBSQMFP73A2X6-gWLVpT84We87FPHAawfMAdB493C9L3RSIn6P2/s320/trades+map.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Lifted from <a href="http://science.nasa.gov/science-news/science-at-nasa/2002/10apr_hawaii/">NASA</a>.</td></tr>
</tbody></table>
Our first step in understanding the problem is to understand the trade winds. I am going to cop out a little bit here and say that we will discuss the trade winds in greater depth in a future post. The important thing to understand here is that this is a pattern of prevailing winds in Hawai'i in which the wind blows from the northeast towards the southwest. This pattern dominates our weather here approximately 80% of the time in the summer months, and from 50-60% of the time in the winter months. The trade winds are why the weather is generally pleasant in Hawai'i, and they are caused by the general global atmospheric circulation. The trades bring moist air from the ocean and force it up over the mountains. The weather pattern described in the Mt. Wai'ale'ale problem is a function of the trade winds. <br />
<br />
<h2>
Humidity and temperature...</h2>
<br />
Our second step is to understand humidity. We generally define humidity (very basically) as water vapor in the atmosphere (2). The more water vapor you have in the atmosphere, the higher the humidity. Though there are several ways to measure humidity, here we're going to focus on the relative humidity. This is simply the amount of water vapor in the atmosphere relative to how much the atmosphere could potentially hold. Think of the atmosphere as a glass. A glass can be empty, or full, or partially full. So we think of the size of the glass as the amount of water vapor that the atmosphere could potentially hold, and the amount of water vapor can be thought of as how much water there is in the glass. Therefore the relative humidity is how "full" the glass is. Under normal circumstances humidity ranges from 0% to 100%. That's easy enough.<br />
<br />
Now about that glass.....we can change its size. The way we do this is by changing the temperature. We have a simple relationship: the ability of air to hold water vapor depends on its temperature. The higher the temperature, the more water vapor the air can hold, the lower the temperature, the less. So if you increase the temperature the glass gets bigger, if you decrease it, the glass gets smaller. <br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJ755mYvIRLhAyvoElfhsW1geQbIEzI5HPMqFrxzll12ywUcSdPQ1Ne1DYtx6zpJ_Tz_Q5KnsYRJ5wH0TtqlaJA1rn_npKGaUUtAAhfxuQBRtGI3OAYeeQHKdKZrWi0EXFrX34FrJyuztp/s1600/sat_sp_curve.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJ755mYvIRLhAyvoElfhsW1geQbIEzI5HPMqFrxzll12ywUcSdPQ1Ne1DYtx6zpJ_Tz_Q5KnsYRJ5wH0TtqlaJA1rn_npKGaUUtAAhfxuQBRtGI3OAYeeQHKdKZrWi0EXFrX34FrJyuztp/s400/sat_sp_curve.jpg" width="368" /></a></div>
There's another thing about this as well. The glass doesn't get bigger or smaller at a constant rate. As the temperature increases, the capacity of the air to hold water vapor increases exponentially. That means the hotter it gets, the faster the glass grows, and the colder it gets, the slower the glass shrinks. Check out the graph, which plots temperature (x axis) versus how much water vapor the air can hold (y axis).<br />
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So what happens if it keeps getting colder and colder? The "glass" will get smaller and smaller. Eventually it will get to the point where it can't hold the "water" anymore. You can probably imagine what happens at that point: the water spills out of the glass. A similar thing happens as the air gets colder. Eventually you reach the 100% humidity level, and some of the water vapor has to "spill" out. But in the case of air, the water vapor turns back into water. This is how clouds form (clouds are water, not water vapor). We'll have another post in the future about this topic. But for now you can see what happens: the trade winds bring in moisture-laden air, forcing it up over the mountains. As it rises it cools down, and as it cools it loses its capacity to hold water vapor, until eventually the air becomes saturated, meaning it is holding all the water vapor it can hold. It is at this point that clouds begin to form. If the air continues to rise water vapor continues to be converted back into water, and eventually there is so much water it will rain. <br />
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When the air reaches the top of Mt. Wai'ale'ale it starts coming back down the mountain, and as you might have guessed, it warms up as it moves down the mountain (3). This means that it can hold more water vapor (the "glass" is getting bigger), and so instead of converting water vapor into water, the reverse process happens: water is evaporated into water vapor. The clouds first start to evaporate; when all the clouds are gone any water on the ground starts to evaporate. One thing we assume here is that whenever there are clouds, the humidity is 100%. Clouds indicate that the air is saturated. <br />
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<h2>
So What About the Temperature and Relative Humidity?</h2>
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As the air moves up the mountain, the temperature decreases. That part we know from experience. The interesting thing is that it decreases at a constant rate. We call this rate the adiabatic lapse rate. When the relative humidity is less than 100%, this rate is about 5.5 degrees Fahrenheit per 1000 feet, or .55 degree per 100 feet. If the air travels 1000 feet up the slope, the temperature will decrease 10 degrees; if it travels 1000 feet down slope, it will decrease 10 degrees. This makes sense to us; this is why we sometimes find snow on the top of Mauna Kea. <br />
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The complex thing that throws everybody off (and it's not really that complex) is that the adiabatic lapse rate changes if the humidity is 100% (if the air is saturated). We call the first lapse rate (5.5 degrees/1000ft) the dry adiabatic lapse rate (DAR); when RH% is 100% we use the moist adiabatic lapse rate (MAR). The MAR is (in this example) 3 degrees Fahrenheit per 1000 meters. Why is it lower? The answer is simple, but you need to concentrate and think about it. If the RH is 100% and the temperature continues to decrease, your "glass" is getting smaller and so water vapor must be converted into water. But for every gram of water vapor that turns into water, a significant amount of heat is released into the atmosphere (the latent heat; this will be discussed in a future post). This heating slows down the cooling trend you have with increasing elevation, and that's why the MAR is less than the DAR. Now we have all we need to know to tackle the problem. <br />
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If we start in Hanalei Bay at 80 degrees and follow our air parcel up, the <br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQ9uEnCxM2BcqtlX_pAM5PCvZS5GW9v0eavxUy97ffNi2BMDdpejrY9g7khkr3GuSJRZ19KY9K_OcL65V5ycw_J537K_oN5ufEYi22cyfi6BeF3z6e3Yi0oAJIevI3KG2ML3TMcV_Gvmh-/s1600/IMG_5557.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQ9uEnCxM2BcqtlX_pAM5PCvZS5GW9v0eavxUy97ffNi2BMDdpejrY9g7khkr3GuSJRZ19KY9K_OcL65V5ycw_J537K_oN5ufEYi22cyfi6BeF3z6e3Yi0oAJIevI3KG2ML3TMcV_Gvmh-/s320/IMG_5557.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Does this guy look familiar?</td></tr>
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temperature decreases by 5.5 degrees per 1000 feet. Thus at 1000 feet the temperature is 74.5 degrees and at 2000 feet it is 69 degrees. But we notice at 2000 feet that clouds are forming (the "glass" is full), which means that water vapor is being converted to water and heat energy is being released, which slows the cooling. From this point we use the MAR of 3 degrees per 1000 feet. Thus at 5000 feet the temperature is 60 degrees, and it is raining, raining, raining. Then the air starts to go down the mountain, warming as it descends. The "glass" is getting bigger, but it stays "full" because the air is evaporating the clouds. Now remember that when you make clouds you release heat so the cooling decreases, but when you evaporate clouds you absorb heat energy, so the warming is slower. <br />
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So as we go down the mountain the temperature increases at a rate of 3 degrees per 1000 feet (the MAR) until we get to 3000 feet, which is the cloud base. Remember that clouds mean 100% relative humidity, and so once you leave the clouds the relatively humidity is less than 100%. You may have noticed that cloud base on the windward side is 2000 feet, whereas it's 3000 feet on the leeward side. Why is this? Because there is less moisture available on the leeward side. There is less moisture available because it was raining on the top of Mt. Wai'ale'ale, and so some of that rain flowed down the mountain or infiltrated down into the soil, and so it is no longer in the atmosphere, and no longer available to be evaporated. <br />
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Therefore at 3000 feet we switch back to the DAR of 5.5 degrees per 1000 feet. I'm not going to give away the answer which you should be able to calculate easily, but it should be clear here that the temperature is greater in Waimea bay than it is in Hanalei Bay. It is also much drier, because the relative humidity is lower and the air is trying to evaporate moisture at this point, which leads to dry conditions. <br />
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<h2>
What does this have to do with Mt. Ka'ala?</h2>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLarBkDHn7EfxTXYzBBkeY1YSsEiz9C_7D9of9qlaPBcFMvoUwOcHUxfLKes94kK-4mQWNF3D-n0nbxrirfoLyXnswwaYqlqMzpDWHVEeU6XNfyaXV7ewGLKBu9KoOGKJz_SNnQrxXzRo_/s1600/Kaala+map.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLarBkDHn7EfxTXYzBBkeY1YSsEiz9C_7D9of9qlaPBcFMvoUwOcHUxfLKes94kK-4mQWNF3D-n0nbxrirfoLyXnswwaYqlqMzpDWHVEeU6XNfyaXV7ewGLKBu9KoOGKJz_SNnQrxXzRo_/s400/Kaala+map.gif" width="372" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Map from Hawaii <a href="http://hawaii.gov/dlnr/dofaw/nars/reserves/oahu/mountkaala">DLNR</a> site on Ka'ala.</td></tr>
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Funny you should ask. A couple of weeks ago the crew responsible for this blog made a hike of Mt. Ka'ala, the highest point on Oahu. We started off from the back of Waianae Valley and followed the well-marked trail all the way to the top, which took approximately 4 hours. Along the way we took relative humidity measurements using a <i>sling psychrometer</i>, an instrument you're familiar with if you've ever taken or are currently taking 101 lab at UH, KCC, or HCC. The wind conditions were atypical, meaning that the wind was light and variable. Normally it is quite windy on the top of Ka'ala when the tradewinds are blowing. Still, we noticed a temperature <i>gradient </i>consistent with what we would expect from the explanation above. The temperature decreased at a steady rate with as we climbed. We recorded the measurements in a notebook, and our intention was to provide a data table and graph, but on the way back down we got caught in a very heavy downpour and so our notebook got wet. This is due to the fact that one of the geography crew forgot one of the most important tools for doing geographical fieldwork: a waterproof notebook. <br />
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Anyway, after eating our lunch and horsing around for a bit on the<i>lee </i>side of the mountain the air moves down the slope, warming along the way. As it warms it can take on more water vapor. First it evaporates the clouds, but since some of the air's moisture has been lost in the form of rain, the clouds are quickly evaporated. This is why the cloud base on the lee side is higher than the cloud base on the windward side. This is also why the lee side is usually quite dry; the air descending from the mountains is constantly evaporating available moisture.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3SQeIIGlMBCPbQTxGuKttlq-7udBLqanjcuSK4DlCiEGJDktyvoJrz32Ic_I-g2v9fRWLHWHCDhtq8ZP6FLRBJ8hTVw_59bmExD0MiEiFZDTyJdvdXXmucGeW6XSvSxbt64tqwMq4xu_0/s1600/IMG_5552.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3SQeIIGlMBCPbQTxGuKttlq-7udBLqanjcuSK4DlCiEGJDktyvoJrz32Ic_I-g2v9fRWLHWHCDhtq8ZP6FLRBJ8hTVw_59bmExD0MiEiFZDTyJdvdXXmucGeW6XSvSxbt64tqwMq4xu_0/s320/IMG_5552.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Geography John demonstrating proper<br />sling psychrometer technique</td></tr>
</tbody></table>
top of Ka'ala, the wind started to change, bringing moist air off the ocean into the mountain, which is consistent with tradewind conditions. As mentioned above, as the air rises over the mountain it loses its capacity to hold water vapor, which forces condensation and eventually it starts to rain. On the way down we got drenched, but eventually we descended far enough so that we were out of the rain. This should make sense given our understanding of how all this works; on the <br />
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That about does it for this post. In our next post one of the geography crew will explain about the vegetation zones you typically encounter as your elevation increases in Hawai'i, providing some examples from the Ka'ala trip. Stay tuned!<br />
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<h2>
Key Terms</h2>
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<u>Gradient</u>: a change of a particular variable over distance. For example, the higher you go up a mountain the colder it is. There is a strong temperature gradient. Another example can be seen with rainfall; Hawai'i has very noticeable rainfall gradients. If you start in Waikiki, there is very little rain, but once you make it to the back of Manoa valley it is very rainy. There is a very sharp change over distance, hence a strong gradient.<br />
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<u>Leeward</u>: The leeward side of the island is the one that the prevailing wind blows away from. In Hawai'i the prevailing winds are the trades, which blow from the northeast and east, so the leeward side is the south and east sides of the islands.<br />
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<u>Windward</u>: The windward side of the island is the one on which the prevailing wind blows. In Hawai'i this is normally the northeast and east sides of the islands. <br />
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<h2>
Discussion Questions</h2>
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<i>Question 1: If the temperature increases, what would happen to the relative humidity? What about if the temperature decreases?</i><br />
<h2>
Notes</h2>
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(1) We would generally refer to this as a northwesterly wind. We always name the wind for the direction from which it blows. So a wind blowing from the south is a southerly wind, one from the east is an easterly wind, and so forth. <br />
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(2) In geography we deal with water in three states: solid (ice), liquid (water), and gas (water vapor). It is the last of these that concerns us here. The air always has a certain amount of water vapor in it, and this water vapor is invisible. <br />
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(3) Rising air cools, sinking air warms up. <br />
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Geografika Nusantarahttp://www.blogger.com/profile/02009398091652720545noreply@blogger.com0tag:blogger.com,1999:blog-5257536511921094573.post-20745089477342562992013-05-21T23:11:00.001-07:002013-05-21T23:11:16.296-07:00Welcome to "The World in the Box"<br />
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<h2>
E Komo Mai!</h2>
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Welcome to "The World in the Box", a blog written and maintained by teaching faculty from several campuses in the University of Hawai'i system. You may have been directed to this blog as part of an assignment; if so we hope you find the information here useful. If you've randomly ended up here as the result of a google search, welcome to you as well, and we hope you will enjoy the content of our blog. We welcome questions and comments, but please remember to remain respectful of others. Our goal with this blog is to create a space where we can interact with students and others interested in the geography of Hawai'i in an informal way; we hope this blog will not only enable us to discuss and elaborate on material from the courses we teach but also serve as a forum to talk about other aspects of Hawai'i.<br />
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This brings us to the title of the blog. You may be wondering what "the world inside the box" means. It's really quite simple. We frequently see maps of the United States, and Hawai'i is generally shown in a little box tucked away into a corner of the map. This gives the sense of remoteness and isolation. But for us as geographers Hawai'i is a fascinating place, full of diversity and wonder. From the geographer's perspective, few places on Earth provide the same opportunity to learn so much, from physical geography topics like climate and volcanology to biogeography and human geography topics like the culture and history of the Hawaiian people. <br />
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For example, did you know that Hawai'i has some of the steepest gradients in all of the world? This means that you can walk from an alpine shrub ecosystem, through tropical rainforest, and end up in a desert over the space of just a few kilometers! Did you know that Hawai'i is home to a carnivorous caterpillar that ambushes flies? Or that our islands have more species of flightless flies than any other place on the planet? While flies aren't the most glamorous of species, the tremendous diversity of species indicates just how special these islands are. You no doubt are aware that these islands are volcanic in origin, and we can see island-forming processes in action on the Big Island. People come from all over the world to study about volcanoes in Hawaii, and the Hawaiian names for the two basic types of lava, a'a and pahoehoe are used by geographers and volcanologists all over the world. Hawai'i is also home to native people with a fascinating history and culture, and the Old Hawaiians were excellent geographers. <br />
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We will be discussing all these subjects and more with this blog. So again we welcome you to "The World in the Box". We hope this blog will help you to appreciate the incredible beauty and wonder of these islands. We also hope it will help you to understand concepts from your classes.<br />
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<h2>
A Hui Hou!</h2>
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Geografika Nusantarahttp://www.blogger.com/profile/02009398091652720545noreply@blogger.com0