Physical Geography of the Big island of Hawaii

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

Lab Stage A. Helpful background material related to the lab

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

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

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.

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.

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.

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.

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.

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

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.

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.

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˚.

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.

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.

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.

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.

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

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).

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 Hawaiʻi 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.

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.

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

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.

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.

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.

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).

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.

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 the cinder cone) or the depth (e.g. of the caldera) using the elevation data you see in the geovisualization. If the location is a basalt lava flow, then the best match will be the volcano that is the source of the lava flow. Just follow the lava flow uphill and when you can’t see it anymore – that’s the source. It will be one of the five big shield volcanoes.

EXAMPLE QUESTION B1. Select the best match between the location and the volcanic feature (or the basalt flow source). If the feature has positive relief (goes up), then estimate its height using the highest elevation at the top and the lowest elevation around its base. If the feature is a negative relief (depression), then measure the highest location at the edge and the lowest education at the bottom to estimate the maximum depth. Locations (that will be randomized)

Screenshots with camera angle pulled back

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Note: The avatar is on the black lava flow near the ocean

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Note: The avatar is on a small hill near the summit of Mauna Kea, lower right view

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Note: the avatar is standing in a caldera near the summit of Mauna Loa. The main caldera at the summit is in the background of the screenshot. The color of the lava is quite dark. Thus, the screenshot was brightened up a lot so that some of the features would show up better in this PDF format.

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Note: the avatar is standing on a basalt flow near the ocean. The basalt flow is on the west side of Mauna Loa. If you hop the avatar up the volcano, you will quickly be able to determine that Mauna Loa is the source.

Below, you will find the correct matches in this example question, in the same order as presented in the screenshots above. As long as you have a basic understanding of volcanic features (e.g. basalt lava flow, cinder cone, caldera), and you go to the location in the game and move up the lava flow to its source – the hope is that this question is not difficult. Locations (that will be randomized)

Correct Matches for those locations (but will be randomized by canvas)

Game Screenshot of the Fast Travel Location

19.8481, -155.9460 Hualalai Volcano Hualalai Volcano erupted during 1800- 1801 to produce the lava flow you investigated. It emerged from 5 fissures along the rift zone on the northwest side of this shield volcano. The lava flow made it to the ocean and buried Hawaiian villages along the way.

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Cinder Cone (that does not quite have a cinder cone shape in the game) about 90 m tall

This cinder cone is near the top of Mauna Kea. The cinder cone is about 90 m in height.

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Caldera, about 90 m deep

Lua Hou is a called a crater, but its really a caldera made when the top of a volcano collapses. Craters are smaller, and they can be pit craters (made by collapse) or craters made by the force of an eruption.

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Mauna Loa This 1950 basalt lava flow was part of an eruption that lasted 3 weeks. The volume of lava in this eruption was about the same as what gets erupted out of Kilauea in an active phase in about 3-4 years.

Questions B2 and B3: Patterns of Precipitation and Humidity (Dew point) on the Big Island IDEA OF Question B2: You are supplied with different locations around the Big Island of Hawai’i. You Fast Travel to these locations in the geovisualization, and you match the location to the explanation of the precipitation pattern that you see. SET UP INFORMATION FOR THE FIRST QUESTION: Northeast trade winds prevail most (70%) of the year and generally blow 10-20 mph. Exceptionally strong and gusty trade winds occur when the sub-tropical high of the central North Pacific Ocean intensifies. These can reach 40-60 mph in the coastal zone of Hawaii, sometimes for several days at a time.

When the trade winds encounter the volcanoes of the Big Island, they rise. Rising

air cools, condenses into clouds, and rain is enhanced in by this “orographic” (mountain) effect. Then, when air descends on the lee side of the volcanoes, the air warms as it descends adiabatically. Hence, the clouds evaporate and the air has a lower relative humidity.

The orographic effect is capped on the Big Island by the Trade Wind Inversion (TWI). Descending air in the Hadley circulation cell does not reach the ground at the latitude of Hawaii, but it gets close to the surface. The elevation of this TWI varies daily and seasonally, but you can see its average position very clearly in the geovisualization where the rainfall and the dew points drop off dramatically.

There is yet a fourth pattern in the precipitation of the Big Island, a summer precipitation maximum on the Kona Coast on the western side of Mauna Loa and Hualalai volcanoes. These North and South Kona Districts on the Island of Hawaiʻi have a unique rainfall pattern. The west-facing slopes of Hualalai and Mauna Loa are sheltered from the trade winds. But, as air flows around the large mountains, it curves back on the leeward side and flows up these slopes, producing a belt of persistent clouds and rain. This area 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 Hawaiʻi with an afternoon rainfall peak, and

with more rain in the summer than other seasons (see mean monthly rainfall at Kona station Honaunau, below and the map of Big Island winds below).

So in total, there are four explanations of the pattern you see in precipitation across the Big Island of Hawai’i. They are:

1. Orographic effects of the northeasterly trade winds 2. Rainshadow effects on the lee sides of the volcanoes 3. Trade wind inversion capping the orographic effect at a certain height 4. Land-sea interaction (afternoon sea breeze) and complex wind patterns (curving

of winds around volcanoes) above Kona on the west side of the island.

EXAMPLE QUESTION B2: You are given four different geographic locations on the Big Island that display a different aspect of precipitation variations. Please match the cause of the precipitation pattern that you see in the geovisualization to the location. In Canvas, there are a pool of questions that have these same causes. However, you will be supplied different locations to visit in the geovisualization via fast travel. You will see the precipitation in the mean annual precipitation surface in the game. Please understand that canvas will scramble the match, but the correct answers are displayed below for you to investigate in the geovisualization. Just click on the precipitation to see the precipitation variations explained in the example. Location Cause 20.1543 -155.7373 The easterly trade winds are forced to rise when they encounter

the Hawaiian volcanoes. This is called an orographic effect, where the rising air cools, condenses, forms clouds and enhances rainfall through this orographic (mountain forced) uplift.

20.1130 -155.8113 Rainshadows are caused by descending air in the lee of a mountain range (or large volcano). The trade winds reach the top of the Hawaiian volcanoes and descend on their west side. Descending air is compressed, and this compression causes warming at a rate of 10˚C per 1000 meters. This is called adiabatic warning. Warming means that clouds can evaporate and this leads to a reduced amount of precipitation called a rainshadow.

19.8309 -155.4117 The Trade Wind Inversion is a key reason why precipitation amounts are so low above 2300 m on the Big Island. The trade winds and their moist marine air dominate below this altitude. However, above 2300 m, the air is descending as part of the Hadley Cell. The descending air starts at the top of the troposphere and has low amounts of water vapor and hence low precipitation amounts.

19.5685 -155.9013 During summer, the North and South Kona Districts of the Big Island have belt of precipitation on the west-facing slopes of Hualalai and Mauna Loa. This area is sheltered from the trade winds, except as air wraps around these volcanoes, it curves back to the island and flows up slopes. Air flowing up slope cools, condenses and produces a belt of persistent clouds and rain. This uplift is enhanced in the summer afternoon as morning sun heats up the slopes, producing a sea breeze enhancement to the uplift.

The screenshots from these locations in the geovisualization are shown below with the camera angle pulled back. Location Cause 20.1543 – 155.7373 Trade Wind Orographic Effect

20.1130 – 155.8113 Rainshadow of the trade winds

19.8309 – 155.4117 Trade wind inversion

19.5685 – 155.9013 Belt of precipitation on the west-facing slopes of Hualalai and Mauna Loa

SET UP INFORMATION FOR THE NEXT QUESTION: Dew point is the temperature at which condensation occurs. You see dew on the ground when the air temperature right next to the surface cools to the point where dew forms. You see that temperature visually when you look at the flat bottom of a cumulus cloud, because the air was lifted and cooled adiabatically to that dew point. Dew point is a much more understandable measure of the amount of water vapor (gaseous water) in the air than grams per cubic centimeters. In fact, news broadcasts often present dew point as an index of misery in the summer, but there is no official “muggy meter” or “misery index”. It all depends on you and what you like.

There is, however, an official heat index, and there is a calculator that allows you to use air temperature and dew point to calculate that heat index: https://www.wpc.ncep.noaa.gov/html/heatindex.shtml Or, if you wish, you can use this formula or refer to the graphic below Heat Index = -42.379 + 2.04901523T + 10.14333127R – 0.22475541TR – 6.83783 x 10-3T2 – 5.481717 x 10-2R2 + 1.22874 x 10-3T2R + 8.5282 x 10-4TR2 – 1.99 x 10-6T2R2T – air temperature (F)R – relative humidity (percentage)

You can also just read the heat index from this NOAA table: https://www.weather.gov/media/jetstream/global/heatindex_chart_dp.pdf The chart looks like this, but you’ll need the higher resolution to see anything:

The dew points of the Big Island are influenced by the same thing as the rainfall. The trade winds below the trade wind inversion contain a lot of tropical water vapor. Above the trade wind inversion, however, the air is bone dry because it has been coming from the top of the troposphere, where there is a lot less water vapor. The moist trade winds mix with the dry air right around the trade wind inversion, where there is a very big gradient. This next question asks you to visit two different locations on the Big Island that have experienced the same temperatures on the same day. We researched this using weather station data, as well as data gathered from different scientific research projects. What you will do in this next question is simply calculate the HEAT INDEX for these two different locations. You will obtain the dew point information from the geovisualization and then use either (i) the website, (ii) the formula, or (iii) the dew point graphic on the previous page to answer the question. EXAMPLE QUESTION A3: Go to 19.4201 -155.2884 coordinates where at 10 am on May 15, the temperature was 84˚ F. Write down the dew point that you see in the geovisualization. Then, go to 19.7595 -155.4561 coordinates where at 2pm on May 15, the temperature was 84˚ F. Write down the dew point that you see in the geovisualization. What’s the heat index for these two spots? The example is provided below in one row. The second row is for your convenience when you answer the question. Site Dew

point Time Temp

˚F Heat Index

Site Dew point

Time Temp ˚F

Heat Index

Visitor Center HVO 19.4201 -155.2884

55 ˚F 10 am 84 ˚F 83˚ F Onizuka Astro Center 19.7595 -155.4561

28 F 2 pm 84 F 81˚ F

Question B4: Geomorphology processes changing volcanoes SET UP TO THIS QUESTION: This question tasks you with analyzing the relationship between rainfall and the development of river valleys on the oldest of the volcanoes on the Big Island, Kohala. Kohala started to develop about a million years ago, building up from the sea floor. It probably reached sea level about a half-million years ago and build its shield shape between 0.5 and 0.25 million years ago. Kohala did have a few small eruptions afterwards, but its last known lava flow is 120,000 years ago. There are lots of different geomorphology processes that alter volcanic features, and the major ones are discussed in the background section of this PDF file. This particular question focuses on the asymmetric development of river valleys. The side of Kohala facing the trade winds has developed deep valleys with Honokane Nui being the deepest one. These valleys have eroded into the basic shield shape of Kohala. In contrast, the leewards west-facing side has only small river valleys with the biggest being Honokoa Gulch. Honokoa Gulch Honokane Nui

You will be analyzing the differences in the depth of incision (downward erosion) of the biggest river valleys on the east-facing and west-facing sides of Kohala, and you will also be analyzing the amount of precipitation falling the different sides. EXAMPLE QUESTION: Using Fast Travel, take your avatar to the Honokane Nui valley of the Kohala volcano (20.1967, -155.7204) and walk up the river valley towards the summit caldera Kohala volcano (20.0803, -155.7139). When the valley splits into two tributaries, take the split to the left (east fork) as you are walking up.

This is a screenshot of the avatar standing on the ridge above the Honokane Nui Valley Note the elevation is 215 m . Since the valley bottom is 35 m, the depth at this location is 180 m. NOTE: the precipitation should be read at the bottom of the river valley.

This is a screenshot of the avatar standing in and just above Honokoa Gulch a bit upslope from the ocean. The darker shading you see is the Honokoa Gulch. The slight bend in the elevation where the avatar is standing on the right frame is where you will measure the river elevation and also the precipitation. Then, just hop the rabbit up (see left frame) and measure the elevation. The difference is the depth of the river at this spot.

Then, go to the Honokoa Gulch (20.0524, -155.8386) on the western rainshadow side of Kohala, and follow this gulch up towards the caldera of Kohala volcano. These are the two largest river valleys on the east-facing (Honokane Nui) and west-facing sides (Honokoa Gulch ) of Kohala volcano. Part 1: What is the difference (in meters) in the depth of these river valleys at an elevation of 35 m above sea level? Just have your avatar go up to the side of each river and note the elevation difference between the Kohala shield volcano surface above and the river below. Part 2: In the game, examine the mean annual precipitation amounts at an elevation of 35 m on the Honokoa Gulch and Honokane Nui streams. What is the difference (in millimeters of precipitation) at these elevations? Part 3: Keep an eye on the depths of these river valleys and the precipitation amounts in the upper parts of their drainage. Based on your observations in question B2 and also your observations in this question, what is the reason for the differences you observed in parts 1 and 2. Note 1: Measure the mean annual precipitation at the river bottom locations, not on the

ridges above. Round precipitation to the nearest 100 mm above 1000 mm, and round to the nearest 10 mm below 1000 mm.

Note 2: Do your best to locate yourself on the ridge above the river valley on the east side. Write down that elevation and subtract the river elevation to ESTIMATE THE DEPTH of the river valley. The depth measurements will be tricky. The 30 m pixel size limits precision. However, Google Earth is not any better. It also uses 30 m resolutions, but it just has a smoothing algorithm that guesses between the center of the 30 m cells. The ‘bottom line” is that you cannot be precise. Do not worry about trying to get too exact of a measurement. Just get close and you will get the correct answer.

CORRECT ANSWER: Part 1: At an elevation of 35 m, the depth of the Honokane Nui Valley is about 180 m, based on the 215 m elevation of the ridge above the river valley. In contrast, at an elevation of 35 m, the depth of the western Honokoa Gulch is just 60 m, with the area above the valley bottom being at 95 m. Part 2: Precipitation on the windward side facing the trade winds is an order of magnitude greater (2300 mm) as opposed to the 240 mm on the rainshadow side of Kohala Volcano. The likely reason for both differences is the rainshadow effect on the western slope of Kohala volcano. INCORRECT ANSWERS could have incorrect depths in part 1, incorrect mean annual precipitation amounts in part 2, and/or an incorrect reason in part 3. Please realize that when there are incorrect depths or precipitation amounts, the differences will not be trivial—so you should not worry about the exact locations where you make the measurement of depth or precipitation.

Question B5: Limits to tree growth on the east slope of Mauna Loa In this question, you will explore the trade wind inversion and its impact on Hawaiian biogeography, specially trees. 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. In the geovisualization, using the LANDSAT composite overlay, you will be directed to specific locations in the videogame. These locations are near the boundary between the dark green and the brown above. The dark green is forest. The dark brown is a mix of shrubs and dwarf trees, and above that is just shrubs. This change from forest to non-forest above is called the treeline. In this case, it coincides with the trade wind inversion.

Landsat Composite image highlighting the treeline between the Kaʻū and Kapapala Forest Reserves on the southeast side of Mauna Loa

QUESTION INSTRUCTIONS: Using Fast Travel, please visit in the geovisualization at the indicated locations. You will not be sent to the exact location of the treeline. Part of the question involves you looking for the highest elevation of the dark green trees, using the Landsat Composite layer. These are a couple of examples.

There will be a complication — that lava flows have periodically wiped out the vegetation, and then the trees gradually re-establish themselves. Thus, you are to walk to the highest dark green nearby. Write down the elevation, and also switch to precipitation and write down those values.

Then, have your avatar travel directly upslope of this treeline about 500 m higher and write down the mean annual precipitation (MAP 500m+). Then, calculate an average (mean) and range of all data you collected QUESTION: Part 1: What is your mean and range for the trade wind inversion treeline on the southeastern slopes of Mauna Loa – in terms of its elevation and mean annual precipitation (MAP). Round off to the nearest 100. Part 2: 500 m above the treeline locations, how much has the average precipitation declined from the treeline? Round off to the nearest 100. ANSWER: The treeline closest to the indicated coordinates averages 2000 m (range 1900-2000 mm) with a mean annual precipitation averaging 1900 mm (range 1750- 2100). The precipitation drops off by an average of 300 mm just 500 meters upslope from treeline. You can use this table to take notes on the locations in this practice question, and you can also use this table to answer the question you will get in canvas. Lat/Long you are sent to Treeline

Elevation nearby in meters

MAP- at treeline in mm

Elev 500 m higher

MAP 500 m higher

Average Average rounded off to nearest 100

Range THIS IS AN EXAMPLE OF ONE OF THE SITES BELOW, AT TREELINE AND 500 M ABOVE TREELINE

EXPLANATION: Lat/Long you are sent to Treeline

Elevation nearby in meters

MAP- at treeline in mm

Elev 500 m higher

MAP 500 m higher

19.3766 -155.4776 1900 1200 2400 900 19.3772 -155.4928 2100 1100 2600 800 19.3171 -155.5243 2000 1100 2500 800 19.2965 -155.5378 2000 1100 2500 800 19.2686 -155.5672 2000 1100 2500 800 Average 2000 1120 2500 820 Average rounded off to nearest 100

2000 1100 2500 800

Range 1900-2100 1100-1200 2400-2600 800-900 THIS IS ANOTHER EXAMPLE OF ONE OF THE SITES IN THE LIST ABOVE, AT TREELINE AND 500 M ABOVE TREELINE

INCORRECT ANSWERS: Please do not worry if what you wrote down differs a bit from what I wrote down in making this example. What you interpreted as the treeline location will be a little bit different from someone else (like the person making this key). This is the reality of science. Even if you were in the field, looking at the treeline, it would be hard for 10 scientists to agree on the precise location. This is because trees become more scattered at treeline. However, when you average five measurements together, and then when you round off that average to the nearest 100 – simply pick the answer that is closest to what you observed and calculated. The incorrect answers will have some piece of information that is quite far off making it obviously incorrect in this 100-level course.

STAGE C Investigation and more detailed analysis: Exploring the physical geography of the Big Island Hawai’i

Components of the science of Physical Geography

This section covers 5 of the areas of physical geography portrayed in this diagram. Task 1: Focuses on the geological materials that make up the Big Island by exploring differences in Hawaiian volcanoes (geology). Task 2: Deals with an aspect of how long-term climatic changes have altered the physical geography of the Big Island through glaciations during glacial cycles (hydrology and landforms). Task 3: Goes into some detail on adiabatic processes and their importance in orographic rainfall and the rainshadow effect – focusing on Kohala Volcano (climate). Task 4. Deals with the elevation of the Trade Wind Inversion that caps the rainfall on the Big Island. You study this cap in rainfall through analyzing dew points (a measure of the amount of moisture in the atmosphere) and how they change at different elevations (climate). Task 5: Focuses on how volcanic and climatic processes influence establishment of plants on the Big Island on lava flows of different ages (biogeography).

The Fast Travel default locations in the geovisualization takse you to the tops of the ‘big

five’ volcanoes seen in the map above. C1: Differences in volcanic development of volcanoes on the Big Island This task asks you to wander around the volcanoes of Hawai’i in the geovisualization and observe differences in their volcanic development using the Landsat composite image. The background knowledge you will need to make observations are in the volcanoes GPH 111 lecture (linked on the first page of this PDF file), as well as background information presented in section 3 of this PDF file. Here are possible questions that you might be given in canvas that relate to this task. The questions are presented in a table format that allows you to take notes if you wish (e.g. elevation of summits, latitude and longitude location of features you see, other observations) during your geovisualization exploration. The question that you receive in canvas will likely task you to visit particular locations in the geovisualization in order to contextualize the question. Possible question in task 1 Notes made during geovisualization

exploration Which volcano has the basalt flow that has the biggest elevation range (from top to bottom)?

What volcanoes look visually to be the most active, based on the overall darkness of the volcano surface?

Which volcanoes have historic lava flows, as evidenced by dark black lava?

Which volcanoes have large summit calderas due to collapse into emptied magma chambers? Or which ones do not and are in the post-shield stage?

Which volcanoes have abundant cinder cones scattered around near their summits?

What volcanoes have relatively steeper slopes capping the volcano? Relatively flatter slopes around the summit of the volcano?

Which volcanoes have rift zones where clear evidence of lava can be seen in the game flowing down from these rift zones?

Which volcanoes have old-enough surfaces to be incised by stream systems? (Hint: Look carefully around the coastlines, because the river valleys start to form first close to the coast-line and then grow headward towards the volcano summit)

Again, if these terms are confusing, please reread the background information material presented earlier in this PDF file or review the GPH 111 lecture on volcanoes linked to the first page of this PDF file. EXAMPLE QUESTION: Two Questions similar or identical to those in the list above will be delivered to you randomly from a bank of the above questions, where even the same question could have a different set of correct and incorrect multiple choice answers. The first question will be about the stage of the volcano and the second question will be similar to the list above. Question Choices Feedback explaining the answer What volcanoes are in the shield stage? A stage between shield and post-shield? The post-shield stage? Or in the Rejuvenated stage?

There are different wordings in the bank for this question.

Since there are 5 volcanoes and only 4 multiple-choice questions, volcanoes that could BOTH answer a question are possible. Please realize that these “both correct” possibilities have been eliminated from the question bank.

Look around the tops of the 5 big volcanoes. Which of the listed volcanoes has the lowest slopes (flattest terrain) around its summit? Please look at the next page for the sorts of views you can explore in the geovisualization to help answer this question.

Mauna Kea Kohala Kilauea Mauna Loa

Mauna Kea has fairly steep upper parts, which is characteristic of post- shield volcanic activity. Mauna Loa and Kohala have lower slopes than Mauna Kea, but there’s not doubt that the area around the summit of Kilauea has the lowest slopes (smallest elevation change). This very low slope is characteristic of a shield volcano that is in its building stage.

The screenshots below would be the sorts of observations you would make to help answer this question.

Kilauea’s summit is the flattest (lowest slopes). It does not even have the shape of a shield volcano, like Mauna Loa below.

Mauna Loa has low slopes, but nowhere near as flat as Kilauea. If you look at Kohala, it has a shape with summit slopes similar to Mauna Loa.

Hualalai has a pretty steep summit, almost as steep as Mauna Kea.

Stage C2: Figure out how long-term climatic changes have altered the physical geography of the Big Island through glaciations during glacial cycles. THE QUESTION: What is your estimate for the maximum thickness of the Makanaka Ice Cap of Mauna Kea at this location (latitude and longitude) in the geovisualization? SETUP FOR THE QUESTION: Mauna Kea is an old-enough volcano to have been glaciated at least three times in the last 150,000 years. This is what the latest ice cap might have looked like about 15,000 years ago when the ice was melting away. Research done by Professor Dorn of ASU and colleagues has shown that the mountain was glaciated about 150,000 years ago, 65,000 years ago, and the last big glacial pulse called Makanaka was about 21,000 years ago: http://www.public.asu.edu/~atrid/NGRE91.pdf

Image created from Google Earth scenes by ASU student Alexis Ruiz

Determining the thickness of ancient glacial ice may seem a bit esoteric, but it is what physical geographers do in order to reconstruct past climates and understand how Earth responds to climate change. While climate modeling can try to predict the future, many physical geographers think that understanding past conditions is the best way to understand future possibilities. Where there are big mountain ranges with alpine glaciers, we use trimlines.

Ice flow can leave behind a line on the side of a glacial valley and that allows a good estimate for ice thickness. Even when the glacier has completely disappeared such as in Yosemite, it’s possible to make reasonable estimates, as illustrated in this National Park Service reconstruction.

Trimlines do not work well for Mauna Kea. The reason is that the rock type is not strong enough to retain an erosional line. Cinder cones form the topography that sometimes stuck out above the ice cap, and these pieces simply keep moving down the slope and erasing the evidence. This USGS photograph shows glacial deposits (till) underneath a 40,000 year old lava flow, glacial deposits on top of small cinder cones, and also glacial deposits left by ice that was forced to split and go around tall cinder cones. The lighter color of the till is due to accumulated silica glaze rock coatings.

Split flow around and between tall cinder cones certainly did not look like the split glacial flow on Mount Rainier, but this photography may give you the idea.

The graphic below shows the USGS aerial photography (on the right) with splitting glacial flow around and between cinder cones, and the left is what this location looks like in the geovisualization with the camera angle pulled up high well above the avatar (yellow arrow) standing on a cinder cone.

The illustration below shows split flow in the game (left) and in a space shuttle view (right) where the yellow arrows are in the same place with a down-glacier direction.

EXAMPLE QUESTION: What is your estimate for the maximum thickness (in meters) of the Makanaka Ice Cap of Mauna Kea at this location (19.8417, -155.4295) in the geovisualization?

HOW TO ANSWER THIS QUESTION: Step 1: Use fast travel to go to the location, which should be on top of a cinder cone surrounded by the split flow. This is a screenshot of this example location:

Step 2: Write down the elevation of the top of the cinder cone. The ice cap’s top was had to be below the elevation of the cinder cone, or there would be evidence on top. Topography up glacier of cinder cone: Top of the Cinder Cone:

Step 3: Find the height of the cinder cone above the topography that is UP GLACIER of the cinder cone. The glacier would have been flowing downhill, so just jump off the cinder cone top and do the subtraction. That is the answer to the question. ANSWER: The ice cap at this location was less than the 120 m height of the cinder cone top above the topography on the up-glacier side of the cinder cone. EXPLANATION: I wrote down an elevation of 3785 for the unglaciated top of the cinder cone at 19.8417, -155.4295 and an elevation of 3665 for the glaciated upside of the cinder cone at 19.8407, -155.4342. Thus, the thickness of the ice at this point would have been less than 120 m (3785-3665 = 120).

SECOND RELATED QUESTION ON GLACIAL THICKNESS: Determine the average of these thicknesses, and then use that average ice thickness to calculate the total volume of the ice cap that was on top of Mauna Kea about 21,0000 years ago. Select the best answer in cubic meters. INSTRUCTIONS TO DO AN EXAMPLE QUESTION. How to answer this question:

1. You will be supplied with ice cap thickness values for this question, but you will need to calculate the average from those values. For example, other measurements of Mauna Kea ice cap thickness taken at locations different from yours in the previous problem were: 50 m, 60 m, 120 m, 90 m, 60m. The average ice thickness is around 76m.

2. S.C. Porter of the University of Washington measured the area of the Makanaka Ice cap to be about 70 km2. You have to multiply square kilometers by a million to obtain square meters of area. Volume = 76m * 70,000,000m2

3. When you multiply area (square meters) by thickness (meters), you get a volume in cubic meters. The answer in this example is a lot of zeroes. Be careful in adding the commas to separate them out. Volume = 5,320,000,000 cubic meters

ANSWER AND EXPLANATION: The format of the answer could be in numbers of words, like 5.3 billion cubic meters. It could be in the format of a number like 5,320,000,000. But the correct answer has to follow the instructions of cubic meters. How can you relate? The photograph below is of Mount Rainier near Seattle (along with an ASU student). The total volume of ice on this volcano is about 2.9 billion cubic meters today. That means that the volume of the Mauna Kea ice cap was almost double Rainier.

C3: Trade Winds, Orographic Rainfall and Rainshadow Effects Easterly winds encounter the topography of Hawai’i and the air is forced to rise. As it rises, it cools. Clouds form (lifting condensation level or LCL). There’s rain as a result. However, on the lee (western) side, the air only warms from compression. Thus, there is a lot less rain on the rainshadow (lee or western) side.

All of the questions in the pool will give you a starting temperature and the dew point (temperature when clouds begin to form). For this example problem, use a typical temperature of 25˚C for the eastern coastline of the Big Island. Use a dew point of 15˚ C. The dry adiabatic rate of cooling from just uplift is 10˚ C per 1000 meters. The wet (or moist) adiabatic lapse rate is not as drastic of a temperature change. In Hawaii, it is typically 5˚C per 1000 m. This slower rate of cooling is due to the release of energy (latent heat) when water vapor is turned into liquid (in the form of cloud droplets). EXAMPLE QUESTION AND PROBLEM: Follow a parcel of air from sea level, up and over Kohala. Calculate the temperature changes along the way every 500 meters. The correct answer will have three parts: (1) Calculate at what elevation the clouds start to form (lifting condensation level). (2) Determine out how much warmer the air temperature is at the coast line on the western side of Kohala than the sea level on the eastern side of Kohala. (3) In the geovisualization, determine the mean annual precipitation (MAP) at the given longitude and latitude locations as the parcel of air goes up and then down Kohala.

The following chart will help you take notes as you analyze what happens to the air parcel. Remember, the air goes east (right) to west (left), not like you read.

ANSWER: Clouds start to form at about 1000 m. The air is about 2.5˚C warmer on the western side than the eastern side. Mean annual precipitation goes from 2300 mm (0 m), to 2400 mm (500 m), to 4000 (1000 m), to 3300 (1500 m), to 800 mm (1000 m on the west side), to 400 mm (500 m on the west side), to 250 mm (0 m) on the west side.

INCORRECT ANSWERS: The incorrect answers will not try to fool you with answers that are super close. The incorrect answers, instead, will catch error of comprehension. EXPLANATION OF THE ANSWER: The diagram above illustrates what happens to the temperature. The air rises and cools at the dry adiabatic lapse rate (10˚ C per 1000 m and that is 5˚ C per 500 m). Thus, the air reaches the 15˚C dew point at 1000 m. From that point, it cools at 2.5˚ C per 500 m and so its 12.5˚ C at the summit at about 1500 m. Then, it warms 15˚ C as its drops 1500 m. The rate of warming going down is always 10˚ C/1000 m, because there’s only air compression going on (no latent heat release). You probably noted that the maximum mean annual precipitation does NOT occur at the highest elevation (as you might expect). It occurs as the air is rising up towards the high points of Kohala volcano. The reason has to do with the air drying a bit because of the influence of the trade wind inversion. [Descending air from higher up in the atmosphere mixes with the trade wind moisture and the amount of water vapor drops a bit The intense drop off in precipitation on the lee (west) side is due to the rainshadow effect of descending and warming air, just as the increase in rainfall on the eastern (windward) side is due to the uplift (orographic effect) of the trade winds.

C4: Understanding the Trade Wind Inversion through Analyzing Dew points BACKGROUND FOR THE QUESTION IN TASK 4: The trade wind inversion (TWI) is a transition layer between moist marine air and much drier air descending from the upper level of the troposphere, associated with the Hadley Cell.

The trade winds underneath the TWI have very high dew points, due to evaporation of the tropical ocean around Hawaii. Turbulence in the lower part of the atmosphere is common, along with cloud development. This turbulence leads to mixing of some moisture around the TWI. However, above this zone of mixing is much drier air, and at the elevations around the summits Mauna Loa and Mauna Kea, the air flow is actually part of the westerlies. This is an idealized diagram from Cecilia Grindinger:

The diagram below from Grindinger is of a sounding up into the atmosphere measuring how air temperature and dew point change at different altitudes. Note that the temperature jumps just a little bit (from about 9˚C to about 13˚C, reading the horizontal scale) at about 2300 m on this day and time. At the same elevation, you can see a remarkable drop in dew point from about 9˚C to about -15˚C. These changes occur over a vertical distance of just a few hundred meters.

The elevation of the TWI in these graphcs is portrayed at about 2200m, but this is a generalization. It will vary in elevation at different locations across the Big Island. Also, keep in mind that the elevation of the TWI changes from day to day and even within a same day. The dew points that you see in the geovisualization are an average annual condition. Thus, when you visit the Big Island and observe the effects, what you analyze here could shift up and down a bit. The question for this task asks you to identify the elevation of the biggest dew point gradient, using the information in the geovisualization. You will be tasked with walking down from the summit of either Hualalai, Mauna Loa, or Mauna Kea and writing down the dew points you observe at different elevations. Then, you will identify the elevation where you see the BIGGEST CHANGE in dew points.

EXAMPLE QUESTION: In a transect of dew points from the summit of Mauna Kea and walking north in the geovisualization, what 500 meters of elevation change had the LEAST change (lowest gradient) in dewpoint change? Also, what is that gradient measured in ˚F per 100 meters (˚F/100m) EXAMPLE QUESTION INSTRUCTION: Fast travel to the summit of Mauna Kea at 4236 m at 19.8230 -155.4696. Walk in a straight northern direction from the summit of Mauna Kea. Start at the summit, then go to 4000 m. Write down the dew points you see in the geovisualization every 500 meters (find the elevation closest to every 500 m). Then, just look at the data you’ve collected and identify the 500 meters in the elevation profile where you see the biggest CHANGE (increase in dew point) over an elevation difference of 500 meters. This table is for your convenience. Summit Elevation: Summit dewpoint: Elev 4000 3500 3000 2500 2000 1500 1000 500 35 m

in game but treat as 0m

Dew point

Gradient ˚F/100m

NOTE: to calculate the gradient: Step (1) find the difference (substraction) in dew points between the elevations; step (2) divide by 5 (not 500), because the units are ˚F change per 100 m. You can fill out the gradient row by starting on the right cell, and it will be the gradient from 500 m to 0 m (sea level). The next cell will be 1000 to 500 m and so forth. NOTE: You might be doing the full elevation dew point transect of a volcano. Or, in some questions, you will be asked to only examine the dew point between two different elevations on the side of a volcano, READ THE QUESTION CAREFULLY. Landsat composite view from the top of Mauna Kea looking north

Dew Point from the summit

Dew Point from 4000 m

Dew Point from 3000 m

Dew Point from 2000 m

Dew Point from 1000 m NOTE: the sea level dewpoint on this transect is 66˚ F

QUESTION: In a transect of dew points from the summit of Mauna Kea and walking north in the geovisualization, what 500 meters of elevation change had the LEAST change (lowest gradient) in dewpoint change? Also, what is that gradient measured in ˚F per 100 meters (˚F/100m). ANSWER: The lowest dew point gradient is 0.6˚F/100m, and it is from 500 m to sea level (35 m in the game, but treat as 0 in the gradient calculations). The reason is that the lowest parts of the atmosphere has been picking up water vapor over a long stretch of ocean surface. Thus, its reached its equilibrium and absorbed what it can. Please note that your question will be different in wording, and so read it carefully. Summit 4175: 12˚ F Elev 4000 3500 3000 2500 2000 1500 1000 500 35 m

but treat as 0m

Dew point

12˚ F 20˚ F 28˚ F 36˚ F 42˚ F 50˚ F 58˚ F 63˚ F 66˚ F

Gradient ˚F/100m

0 from 4175 to 4000

1.6 1.6 1.6 1.2 1.6 1.6 1 0.6

Task 5: How volcanic and climatic processes influence the biogeography of plants on the Big Island. One of the most important basic concepts in the biogeography part of physical geography is plant succession. This is the explanation in two great physical geography online textbooks http://www.physicalgeography.net/fundamentals/9i.html https://www.earthonlinemedia.com/ebooks/tpe_3e/biogeography/plant_succession.html The basic idea is that a mature vegetation group of plants will get disturbed by processes such as forest fires, bulldozers, and even lava flows. Then, after the disturbance, a series of changes over time take place. This is a very common type of diagram for the eastern United States:

However, the way that plant changes after disturbance works varies a lot in different places, and climate matters a lot. The Big Island is a wonderful place to understand plant succession and how long it takes, because the ages of the lava flows are known using radiocarbon dating. A classic study of plant succession by Mueller0Dombois and Boehmer studied lava flows on the east-facing windward side of the Big Island. This is where the trade winds are uplifted orographically and the rain is abundant. The next graphic is are a series of screenshots from their paper with their basic conclusions that the transition from a new lava flow to a tropical rainforest occurs by 400 years.

Generally, stages 2-4 in the “Early Development” phase can be described in the pictures on the right side. Organisms like lichens, mosses, fungi, ferns and bryophytes start to cover the lava flow surfaces, but the flow surfaces are still very noticeable. Then, in about 50 years, trees start to come in and the density of trees continues to increase until the lava flow is covered with a tropical rainforest by about 400 years. Thus, there are three general stages: 1) new lava flow 2) lichens and other epilithic (rock surface) organisms cover the surface and change is appearance 3) forest takes over

The geovisualization shows the basic changes from this study. The screenshots of the geovisualization at different places are compared to what is seen on the ground. Please take note of how these succession changes look on the windward (trade wind facing east side) side of the Big Island, because you will be answering a matching question on this.

The rainshadow side of the Big Island also has plant succession, but it is much slower. It takes over 10,000 years to go from a fresh lava flow to the end-vegetation type of desert scrub and small trees some times called kiawe (or the tree of life in its native South America). The first step you can see in the geovisualization is still fresh lava (0- 400 years). The second step is the coating of silica glaze (its too dry for lichens and plants like mosses and ferns) that lasts from ~400 years to 3000 years. From 3000 to 5000, grasses come in but the silica glaze covered lava is obvious. Then, grasses and some desert scrub gradually increase from 5000 to 10,000 years. On lava flows older than 10,000 years, the local scrubland-dwarf tree plant association can be dominated by a type of mesquite tree called Prosopis pallida. This mesquite is also called kiawe. It originated in Peru and arrived in Hawai’i in 1828 in a churchyard in Honolulu. It has since spread and grows on the rainshadow sides of the Big island. Its seed pods can be a food source for people and livestock, brewed into a tea or sometimes used to make beer

These are some ground views of the changes from fresh lava, to silica glaze, to desert

scrub vegetation over 10,000 years.

These are views from the geovisualization of these same stages of succession after a new

lava flow.

EXAMPLE CANVAS QUESTIONS ON STAGE B TASK 5: Plant Succession after a lava flow on the windward and leeward sides of the Big Island. The three coordinates are near to one another on the rainshadow side of the Big Island. They represent the three stages in plant succession typically found on the drier semi-arid/desert slopes on the leeward sides of the volcanoes. Select the best matches between location and the stage. Note: there are pools of questions and your choice will not be the same as this example. Also, the example below shows the correct matches. Canvas will automatically scramble your choices. Locations Choices 19.7698 -155.6601 Basalt lava flow less than 200 years 19.7539 -155.6669 Lava flow about 2000-3000 years

old that has been coated with silica glaze giving it a brownish coloration, instead of the original black of the underlying basalt flow.

19.7448 -155.6831 Lava flow that is older than 10,000 years. It has been colonized by a mixture of grassland and desert scrub vegetation including mesquite.

The three coordinates are near to one another on the windward side of the Big Island. They represent the three stages in plant succession typically found on wetter slopes of the Big Island. Select the best matches between location and the stage. Note: there are pools of questions and your choice will not be the same as this example. Also, the example below shows the correct matches. Canvas will automatically scramble your choices. Locations Choices 19.1866 -155.7600 Basalt lava flow less than 50 years 19.1905 -155.7659 Lava flow about 150 years old that

is covered with lichens, ferns, mosses, and scattered trees.

19.1900 155.7991 Lava flow that is about 800 years old, and it is covered in rainforest.

STAGE D: Your analysis of the Physical Geography of the Big Island of Hawai’i This is your chance to combine observations made doing this lab with your own experience (including outside readings and your own travels). Keep in mind that the grading of this essay is based on the evidence and reasoning that you present. Answers that do not refer to specific evidence from this lab (and outside material) will be given little credibility and will not receive full points. In other words, if we do not see clear evidence from this lab (and outside material), do not expect any points. We do not have any particular answer in mind. We want to know your opinion, but backed up by evidence and reasoning (beefy paragraphs). You do not have to do this essay. It simply provides you an opportunity to synthesize the lab and let us know your thinking on the basic questions of the lab. Paragraph 1. Using your understanding of the volcanoes of the Big Island of Hawaii, please summarize their volcanic features. You can pick just one of the volcanoes, or you can generalize for all of them. Paragraph 2. Using your understanding of how geomorphology processes (e.g. development of river valleys, glaciations, rock coatings) have modified the volcanoes of the Big Island, please explain how these processes changed the landforms from their original volcanic morphology and appearance. Paragraph 3. The lab covered some basic processes in climatology and meteorology such as adiabatic processes, condensation of clouds, rainshadow effects, dew point gradients, changes in precipitation from place to place, and the trade wind inversion. Pick two of these processes and explain their importance with an example each for the Big Island. Paragraph 4: The upper elevation treeline on the eastern slopes (southeast-facing, east- facing, and north-east facing) of the volcanoes of the Big Island Hawai’i is a dramatic change in plant geography. Summarize your understanding of this upper elevation treeline in terms of where you would expect to find it, what climatic differences occur at and just above the treeline, and what is responsible for this dramatic change. The point scoring is divided evenly between the paragraphs. The assigning of points is based on the level of detail you provide in writing teach paragraph.

Physical Geography of the Big island of Hawaii

Physical Geography of the Big island of Hawaii

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