Lab Title Physical Geography of the Big

island of Hawai’i What is this lab all about? Lab Worth

You explore the volcanoes, landforms, climate, and vegetation of Hawai’i in a geovisualization, as well as view a traditional lecture on the concepts of geography that influence the Big Island of Hawai’i The points you accumulate for correct answers count towards your grade. Incorrect answers do not hurt your grade.

Computer program used in this lab

You will be given instructions later on how to download the geovisualization of the Big Island in a page in Canvas in the Welcome module. In this program, you are a virtual character able to wander around the Big Island.

Introductory video

The canvas page where you downloaded this file also has a link to an introductory video. The material in that video is a brief synopsis of what is in this PDF document.

SQ general studies criteria

Students analyze geographical data using the scientific method, keeping in mind scientific uncertainty. Students also use mathematics in analyzing rates to change in the landscape.

Table of Contents for this PDF File 1. Preface: What makes the Big Island so special in physical geography? Page 2 2. Overview of lab activities

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Lab Stage A. Helpful background material related to the lab

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Lab Stage B Exploration: Making some basic observations related to the physical geography of the Big Island

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Lab Stage C Investigation: more detailed analysis of the physical geography of the Big Island

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Lab Stage D synthesis: A short essay whose goal rests in you bringing together your thoughts on the physical geography of the Big Island of Hawai’i.

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1. Preface: Physical Geography of the Big island of Hawai’i The Big Island of Hawai’i is a special place for physical geographers to study. There exists such a wide range of climates, all while the geology of basalt lava rock type remains pretty constant. For example, warm desert conditions exist on the western sides of the Hualalai, Mauna Kea, and Kohala shield volcanoes, and cold desert conditions on top of Mauna Kea and Mauna Loa volcanoes. Physical geographers have studied everything from coastal erosion to incision of stream valleys using the variety of conditions on the Big Island. Since physical geographers typically love field work, a plus is the lack of poisonous snakes. Unlike other sciences that task you with analyzing one focused field such as cellular biology, inorganic chemistry, or physics – physical geography concentrates on six general areas of science to try to understand better the great variety of environmental conditions that exist at Earth’s surface. Physical Geography was the world’s first environmental science field, well before everything split off, and it remains focused on interconnections as displayed in the following diagram.

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Components of the science of Physical Geography

The designers of this laboratory hope that you will be able to explore the physical geography of the Big Island in person in the near future. However, in the meantime, this lab transports you to a virtual simulation to analyze three questions that we hope will enhance your in person exploration. In the meantime, the geovisualization of the Big Island is a great way to study its physical geography. The geovisualization looks and plays like a videogame, but one where you explore connections between topography, landforms, climate, and vegetation There is a caveat about the lab: There is no doubt that an online lab about the Big Island is missing out on our five traditional sense of sight (and the changes in lighting), smell and feel the trade winds on your face, the taste of trail and camping food, the smell of plants, and touching of different volcanic rock textures. In the end, you will just have to experience these in Hawai’i for yourself.

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2. Overview of lab activities The purpose of this section is to provide you an overview of the activities you will complete. Before you dig into the lab, you are also welcome to learn extra background information about the Big Island of Hawai’i in the next section. You certainly do not have to read the third section in detail to do this lab, but you will probably find that this enrichment material will help you get more out of the other lab activities. 2.1 Parts of this lab: Begin (Stage 0), Basics (stage A), Exploration (stage B), detailed analysis (stage C), and essay synthesis (stage D) If you have not completed Stage 0, you should stop and do that first. Stage 0 is intended as an orientation to playing the geovisualization ‘game’ and an orientation to doing this lab. Stage 0 is a separate PDF file with separate videos to help you. In the basics stage (stage A) of this lab, you will watch a video or read the text of basic geography concepts that take place on the Big Island. You will then take a short quiz to test your understanding of these concepts. In the exploration of this lab (Stage B), you will get a chance to enhance your grade by learning a bit about the Big Island and the sorts of activities you will engage in if you decide to move onto Stage C. In the detailed analysis part of the lab (Stage C), you will use the video game geovisualization to explore in greater detail the connection between the topography, landforms, climate, and also vegetation of the Big Island. Then, Stage D of the lab encourages you to synthesize what you have learned in writing a short four-paragraph essay on the physical geography of the Big Island. Most of this essay tasks you with covering what you learned in lab activities, but you are also encouraged to explain your own personal perspective on the lab question. 2.2. The study area and the scale of study

The entirety of the Big Island is too much to analyze at a scale where you can see the sorts of features that would be of interest to you on the ground. It just is not possible to include everything in a video game at a large scale of even 1:100 (1 length on the ground to 100 lengths on the map). There is just too much detail. Besides, sometimes it’s possible to lose sight of the forest if you are too buried in the roots of the trees. The big- area (small scale) patterns in physical geography would get lost. Thus, all of the laboratory activities will be at a scale where you can only zoom in just so close. High spatial resolution is not what this laboratory covers, but rather bigger-sized features and processes. The two graphics below show a wonderful map designed and produced by the National Park Service and a famous Landsat 7 mosaic produced by NOAA. Both of them show the study area of this lab.

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Stage A: Basics of the Big Island of Hawai’i The material in this section is also presented in an audiovisual lecture: https://youtu.be/pYr1n4iScVs The content of this section and the lecture are the same and both prepare you for the quiz for Stage A. Background on Volcanoes on the Big Island The Big Island has five major shield volcanoes, where this map is courtesy of the National Park Service. This map also shows the historic lava flows with a red color.

Most of the volcanic eruptions on the Big Island emit from rift zones, where the volcano is splitting apart. There are many cracks where magma makes its way to the surface. The rift zones are ridges on the flanks of the volcanoes, and the magma emerges from the rifts. Rift zones are where most of the lava flows start. They are easiest to see on Mauna Loa and Kilauea. You can also see them on Hualalai pretty clearly. They are harder to see on Kohala because of the vegetation cover.

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All of the “big 5” volcanoes are called shield volcanoes, because they have the shape (in profile) of a shield used in battle. The shape is evident in this famous painting of a Kilauea lava lake and a snow-capped Mauna Loa shield in the background:

The Hawaiian Islands are in the middle of the Pacific plate. Whereas most volcanic activity is associated with divergent and convergent boundaries, the Hawaiian Islands sit on a hot spot in the mantle. This graphic from the U.S. Geological Survey shows how the Kilauea volcano is “plumbed” to this hot spot

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The Pacific Plate has been moving over this hot spot for tens of millions of years, producing first the Emperor chain and then the Hawaiian chain of volcanoes.

The volcanoes on the Big Island of Hawai’i are either in the shield stage, the post-shield stage, or are in transition between shield and post-shield. The Big Island volcanoes are all too young (a million year or less) to be in the rejuvenated stage. The graphic and table below summarizes the sorts of features seen in each of these stages.

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Shield Stage Postshield Rejuvenated

90 percent or more of each volcano above sea level is built during the shield stage, which probably lasts less than 1 million years. The stage is characterized by voluminous eruptions of highly fluid basalt lava, mostly erupted at the volcano’s summit and from rift zones. Most shield volcanoes also have, or have had, a summit caldera. The caldera is not a permanent feature—it can be filled and collapsed.

Postshield rocks form a thin veneer capping shield volcanoes, constituting only about 1 percent of the volume. The postshield stage is characterized by eruptions that are less frequent, lava that is more viscous (sticky), lava flows that are thicker and shorter, eruptions that are more violent, and more common occurrences of cinder cones and ash layers. As a result, the postshield stage commonly forms a bumpy, steeper-sided cap on the shield volcano. Not all shield volcanoes have substantial postshield top.

The Big Island is too young for this stage. Kaua‘i, Ko‘olau, and West Maui volcanoes have rocks of the rejuvenated stage/

The landscape of volcanic regions in Hawai’i can be defined by these rift zones and pit craters. These are shaped by the force of eruptions as well as crater collapses.

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Background on Geomorphology modification of Hawaiian volcanoes This 100-level lab covers four different ways that physical geography processes modify the Hawaiian volcanoes: the development of deep river valleys; the collapse (landsliding) of volcanoes into the ocean; glaciations on top of Mauna Kea, and coating of bare rock surfaces with silica glaze hence changing the surface appearance of the rocks. Development of deep river valleys Hawaiian volcanoes have the gentle slope of a shield volcano. However, if there is enough rainfall, these gentle slopes will undergo rock decay (weathering) that allows the development of deep river valleys. In the diagram below created by Dr. T.M. Oberlander, the valleys grow headward into the shield volcano where waterfalls cascade into them. They also grow through landsliding of the valley sides during extreme rain events. The side slopes of these valleys can be very steep, exceeding 50?.

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Large hurricanes are not as frequent in Hawai’i as you might think, given its position in the middle of the tropical Pacific Ocean, but when they do occur and produce copious rain – this is when the deep river valleys undergo the most change, such as with Hurricane Douglas in the summer of 2020, here seen approaching the Hawaiian Islands.

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Collapse of volcanoes into large landslides. The exact cause of these massive landslides all over the Hawaiian islands is not known. Certainly, it has to do with structural weaknesses along the side of a volcano. There could be earthquakes involved as well. These landslies can be spectacularly large where the sides of the volcanoes collapse out onto the ocean floor. This is a map of some of these collapses from the U.S. Geological Survey.

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Background on the Glacial Ice Cap on Mauna Kea The Big Island had glaciers on top of its highest peaks several times during the last 200,000 years. It may have had glacial ice caps earlier, but the evidence has been lost. Any aliens visiting Earth might about 20,000 years ago might have looked down at Mauna Kea, and the scene might have looked like this artistic reconstruction:

Artistic vision of what Mauna Kea may have looked like at the height of the last glaciation around 20,000 years ago, created by ASU student Alexis Ruiz on a base map of a Space Shuttle photograph.

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The image below shows what the top of Mauna Kea looks like. You can see subtle color differences between glacial deposits of two different time periods. The Makanaka glacial deposits are much lighter in color than the older Waihu glacial deposits, and both are much lighter than the unglaciated volcanic features. The color differences are due to the accumulation of a rock coating called silica glaze. Silica glaze is about the thickness of human hair, but it makes a giant difference in the appearance of landforms on the Big Island. The image on the right shows a close up of the silica glaze.

A direct overhead view from the International Space Station of the top of Mauna Kea shows the same thing, but only over the entirety of the top of the mountain. So you can see the same locations, Makanaka and Waihu have been placed in the same locations as the Google Earth image above.

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3.2.4. Silica glaze (and other rock coatings) change the appearance of rock surfaces. Silica glaze coats all of the rocks in Hawaii, and it even changes the color of fresh lava flows turning them brown. Even a coating as thin as your hair (lower left) turns a black lava flow light brown. On top of Mauna Kea, it turns the glacial boulders whitish. The lower left is an electron microscope view with the scale bar only 5 micrometers. The lower right view is a satellite image of lava flows whose color change (from black to lighter) is due to silica glaze accumulation on bare rock surfaces.

Background on the Climate of Hawai’i Introduction The climate of an area is a composite or frequency distribution of various kinds of weather. The outstanding features of Hawaii’s climate include mild temperatures throughout the year, moderate humidity, persistence of northeasterly trade winds, significant differences in rainfall within short distances, and infrequent severe storms. For most of Hawaii, there are only two seasons: “summer,” between May and October, and “winter,” between October and April. Latitude and Maritime Climate Hawaii is in the tropics, where the length of day and temperature are relatively uniform throughout the year.Hawaii’s longest and shortest days are about 13 1/2 hours and 11 hours, respectively, compared with 14 1/2 and 10 hours for Southern California and 15 1/2 hours and 8 1/2 hours for Maine. Uniform day lengths result in small seasonal variations in incoming solar radiation and, therefore, temperature. On a clear winter day, level ground in Hawaii receives at least 67 percent as much solar energy between sunrise and sunset as it does on a clear summer day. By comparison the percentages are only 33 and 20 at latitudes 40 and 50 degrees respectively. The ocean supplies moisture to the air and acts as a giant thermostat, since its own temperature varies little compared with that of large land masses. The seasonal range of

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sea surface temperatures near Hawaii is only about 6 degrees, from a low of 73 or 74 degrees between late February and March to a high near 80 degrees in late September or early October. The variation from night to day is one or two degrees. Hawaii is more than 2,000 miles from the nearest continental land mass. Therefore, air that reaches it, regardless of source, spends enough time over the ocean to moderate its initial harsher properties. Arctic air that reaches Hawaii, during the winter, may have a temperature increase by as much as 100 degrees during its passage over the waters of the North Pacific. Hawaii’s warmest months are not June and July, but August and September. Its coolest months, are not December and January, but February and March, reflecting the seasonal lag in the ocean’s temperature. Hawai’i does not have the extremes of cold winters and summer heat waves and it usually does not have hurricanes and hailstorms. However, Hawaii’s tallest peaks do get their share of winter blizzards, ice, and snow. Highest temperatures may reach into the 90s. Thunderstorms, lightning, hail, floods, hurricanes, tornadoes, and droughts are not unknown. However, these phenomena are usually less frequent and less severe than their counterparts in continental regions. The highest temperature ever recorded in Hawaii was 100 at Pahala (elevation 870 feet) on the Big Island of Hawaii on April 27, 1931. The lowest ever recorded was 12 on Mauna Kea (elevation 13,770 feet), also on the Big Island, on May 17, 1979. Winds in Hawai’i During much of the year, a large ridge of high pressure is situated northeast of the Hawaiian islands. This subtropical high causes winds to blow consistently from the northeast, especially during the summer – these are called the trade winds and typically lead to clouds and rain on the eastern sides of the island (windward) with dry, stable air sinking along the western side (leeward).

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During the winter, migratory mid-latitude storms interrupt the subtropical trade winds and result in atmospheric flow from the south/southwest. These are called Kona winds and bring widespread precipitation to much of the island. Sea and land breezes can occur on sheltered sections of leeward coasts, such as around Kona in Hawai’i. These winds are driven by land-sea temperature interactions. During the day, the land heats up and a sea breeze underneath the trade wind inversion takes place. This all leads to belt of persistent clouds and rainfall on the mountain slopes above Kona.

This zone is home to the farms that produce world-famous Kona coffee. Uplift is enhanced in the afternoons when the sun warms these slopes. Strong trade winds and intense heating during the summer also increase lifting, clouds, and rainfall on the Kona slopes. As a result, this is the only area in Hawai?i with an afternoon rainfall peak, and with more rain in the summer than other seasons (see mean monthly rainfall at Kona station Honaunau, below). You will see this belt of precipitation in the geovisualization game.

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Rainfall Patterns and Rain shadows Over the ocean near Hawaii, rainfall averages between 25 and 30 inches a year. The islands receive as much as 15 times that amount in some places and less than one third of it in others. This is caused mainly by orographic or mountain rains, which form within the moist trade wind air as it moves from the sea over the steep and high terrain of the islands. Over the lower islands, the average rainfall distribution resembles closely the topographic contours. Amounts are greatest over upper slopes and crests and least in the leeward lowlands. On the higher mountains, the belt of maximum rainfall lies between 2,000 to 3,000 feet and amounts decrease rapidly with further elevation. As a result, the highest slopes are relatively dry. Another source of rainfall is the towering cumulus clouds that build up over the mountains and interiors on sunny calm afternoons. Although such convective showers may be intense, they are usually brief and localized. Hawaii’s mountains significantly influence every aspect of its weather and climate. The endless variety of peaks, valleys, ridges, and broad slopes gives Hawaii a climate that is different from the surrounding ocean, as well as a climatic variety within the islands. These climatic differences would not exist if the islands were flat and the same size. The mountains obstruct, deflect, and accelerate the flow of air. When warm, moist air rises over windward coasts and slopes, clouds and rainfall are much greater than over the open sea. Leeward areas, where the air descends, tend to be sunny and dry. In places sheltered by terrain, local air movements are significantly different from winds in exposed localities. Since temperature decreases with elevation by about 3 degrees per thousand feet, Hawaii’s mountains, which extend from sea level to nearly 14,000 feet, contain a climatic range from the tropic to the sub-Arctic.

This is a view looking north, where the eastern side is on the right. The trade winds are forced up and over a topographical barrier. The windward side will be cloudy and wet as air ascends, cools, and reaches the dew point (cloud formation occurs) The lee side will be warmer and drier as the air descends – and this is called the rainshadow.

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The image on the next page is famous for its portrayal of the dramatic differences in rainfall on the eastern (right) and western (left) sides of Kohala volcano on the Big Island. Moist trade winds encounter Kohala’s north-east facing side and are forced to rise. Rising air expands and cools due to adiabatic processes. The cooling results in condensation, cloud formation, and lots of rain. However, when this air starts descending on the southwestern side, it warms. The opposite happens. Warming leads to cloud evaporation and much less rainfall. The effect is clearly dramatic in this image taken from the Space Shuttle. You can also see differences in the development of river valleys. Both sides of Kohala volcano are pretty much the same age. Its shield-building stage ended about 250,000 years ago. Since then, only small volcanic eruptions have occurred, such as the cinder cones you can see along the summit. The valley cutting that you see on the northeast-facing side have occurred in the last quarter mission years. However, its only been wet enough to do this on that windward side of Kohala. It is the rainfall that concentrates in the stream that cuts the river valleys.

https://eol.jsc.nasa.gov/SearchPhotos/photo.pl?mission=STS051&roll=102&frame=83

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The image above shows you a mean monthly precipitation at two weather stations on the windward side of Mauna Loa and on the leeward side. Please focus on the vertical scale. The amount of precipitation is a lot lower on the leeward side. The station on the leeward side is actually in one of the wetter locations on the western side of the Big island. It is much drier a bit to the north. Trade Wind Inversions The image below shows the latitudes between the equator and just north of Hawaii at the subtropical high (on the right). Hawaii is between. All the basic presentations about the Earth’s general circulation systems show this circulation cell (trade winds converge on the equator as the red lines and then return as the dark blue line to the subtropical high) called the Hadley Cell.

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However, reality is more complicated. The air starts to descend in the latitudes of Hawaii, but it just down not reach the surface. It typically reaches an elevation that ranges from 1800 to 2400 meters (6000 to 8000 feet). Then, this descending air creates a TRADE WIND INVERSION. What is the significance of the trade wind inversion? An inversion is where temperature begins to increase with elevation. The normal condition is the reverse, and that’s why its called an “inversion”. Increases in temperature with height is not at all conducive to rainfall. The moist-warm trade winds reach this inversion, and the clouds evaporate as the air warms up (as the air is pushed up slope). Thus, forests stop suddenly, and the vegetation comes scrub and then quickly desert-like, because of the great reduction in rainfall. The below image shows the Trade Wind Inversion’s influence on the temperature with height, in this diagram over Maui’s Haleakala volcano. What this means is that the orographic effect of cloud formation and the associated rainfall is often STOPPED at the Trade Wind Inversion, capping any clouds or precipitation that would occur.

Biogeography Biogeographers focus on plant and animal distributions – what controls them and what might happen in the future given what we know about the past. There are a great many factors that influence plants and where they grow. These controls are typically broken into abiotic factors (e.g. temperature limits, precipitation limits, availability of nutrients) and biotic factors (e,g, how species disperse, competition, predation, parasites & pathogens, mutualism such as symbiosis between fungi and algae in a lichen). At the scale of the Big Island and the LANDSAT composite overlay on the topography of the geovisualization video game, there are two patterns that you will study in this lab. One of them is the upper treeline of the rainforest, and the other is plant succession after the disturbance of a new lava flow destroying the previous vegetation. In mountain ranges in the mid-latitudes and at the highest latitudes, treeline is often controlled by temperature. If there is not enough of a growing system with warm enough temperatures, then trees cannot grow. In mountains, treeline can also be controlled by snow cover that lasts too much of the year to allow trees to grow. However, the upper treeline on the Big Island is not controlled by temperature or snow cover. It is controlled by precipitation.

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In this lab, you will explore the trade wind inversion and its impact on the vegetation – basically where you see a browning of the vegetation is the inversion base, and you will measure its position at different locations on the Big Island. Just take a look at this Landsat composite view of the southeastern slopes of Mauna Loa. The elevation of the dashed line (average position of the trade wind inversion is what you will investigate.

The Big Island is famous in biogeography as a place to study rates of plant succession. The idea is that a disturbance takes place (e.g. a glacier obliterates previous plant life, a fire burns an area, field of crops is abandoned). In the case of the Big Island, an entirely new earth’s surface is formed by basalt lava flows. The Big Island is famous, because the U.S. Geological Survey has determined the ages of these lava flows using radiocarbon dating of charcoal dug out from underneath the flows. This allows plant geographers to study how long it takes plants to re-establish themselves.

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When you consider the great climate variability across the Big Island, Hawaii becomes a perfect setting to understand how orographic rainfall and rainshadow effects (amount of precipitation) influences how fast succession occurs. The Big Island’s plant cover ranges from tropical rainforest on the eastern sides of the island to desert scrub vegetation on the rainshadow side. In the diagram below, you can see side-by-side the area with young lava flows (less than a few thousand years) and the tremendous moisture variability from very wet (dark blue) to very dry (yellow).

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STAGE B: EXPLORING THE BIG ISLAND THROUGH OBSERVATION

Before you go any further, you need to get to know the five main volcanoes of the Big Island of Hawai’i. Just memorize them. It will make it so much easier for you in following the lab questions, and when you are in Hawai’i exploring in person. Start by looking at the top map showing the extent of these volcanoes (and their lava flows), and then recognize them in the context of the surface winds.

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Stage B Exploration: Making some basic observations related to physical geography of the Big Island of Hawai’i Stage B tasks you with exploring what this lab is about by answering questions about different aspects of the Big Island’s physical geography.

! Question B1: Volcano basics ! Questions B2 and B3: Rainfall and dew point patterns ! Question B3: Geomorphology processes changing volcanoes ! Question B4: Limits to Tree Growth

Question B1: Matching – select the best match between the location and the volcanic feature (or the basalt flow source). NOTE: There are a big pool of these questions, and so the instructions here apply for all of the potential questions. You are given geographic coordinates scattered around the Island of Hawai’i. Use Fast Travel in the geovisualization to travel to that location. If the location is a volcanic feature that is not a lava flow (e.g. caldera made by collapse of a volcano into an emptied magma chamber, crater made by the force of a volcanic eruption (surrounded by cinder or lava), a pit crater made by collapse into a void, cinder cone made by lava reaching the surface in the form of pieces called cinder and dropping back down in the shape of a cone), then the correct match will be the correct name of the feature and an estimate of the height (e.g. of …

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