The Western World Daily Readings on Geography Chapter 6 Physical Geography

24 SCOTT CAMPBELL CHAPTER Physical Geography Concepts and Terminology Physical geography is the study of the spatial distribution of environmental features , like , climate , soils , and organisms , and the processes that shape them . Each place on earth possesses its own unique physical characteristics . Here we will look at some basic facts about the earth , and some fundamental concepts of physical geography . LATITUDE AND LONGITUDE As anyone who has taken a basic geometry class knows , the location of a point is defined by the intersection of two lines . What is true in geometry is also true in geography . The location created by Andrew of any place on earth can be defined by the intersection of two from Noun Project parallel of latitude and a meridian of longitude . The earth is rotating around an imaginary line called the rotation axis . The northern end of that axis is called the north pole , and the southern end of the axis is called the south pole . The halfway point between the north and south poles is known as the equator .

PHYSICAL GEOGRAPHY 25 A latitude describes its location relative to the equator , and is an angle defined by two running from that particular place to the center of the earth , and the other running from the center of the earth to the equator . Ifyou trace a line from Chicago straight down to the center of the earth , and another line from the center of the earth to the equator , the angle created by those two lines is about . Because Chicago is north of the equator , its latitude is , the standing for north . The equator is at . Everything north of the equator is in the northern hemisphere . As locations get farther away from the equator , their latitude increases . New Orleans , for example , is closer to the equator than Chicago , and is at latitude . is farther from the equator than Chicago , at Created by Bravo latitude , halfway to the north pole . from Noun Project , It works the same way In the southern hemisphere , which consists ofall areas south of the equator . Ecuador , just south of the equator , is located at ( south ) latitude . A little bit farther away from the equator is Lima , Peru , at latitude . Even farther away from the equator is Buenos Aires , Argentina , at latitude . As you move toward the equator , you are moving to a lower latitude . As you move away from the equator , you are moving to a higher latitude . The north and south poles are the highest possible latitudes , at and . The equator is at the lowest possible latitude . Chicago ( is at a higher latitude than New Orleans ( but at a lower latitude than ( Lima ( is at a higher latitude than ( but at a lower latitude than Buenos Aires ( Keep in mind , the terms higher and lower latitude do always mean up and down on a map . New Orleans is at . Buenos Aires is . New Orleans is above Buenos Aires on a map , but Buenos Aires is at higher latitude , because it is farther from the equator . Parallels of latitude are lines that run east and west on a map , and that connect all places that are at the same latitude . Parallels , as their name implies , are always the same distance from one another , and parallels decrease in length as latitude increases . The equator is the longest parallel of latitude . and are slightly shorter than the equator . and are slightly shorter than that , and so on up to and , which are very short . The poles , at and , have no are points . In addition to the equator and the poles , there are four other important parallels of latitude . The Tropic of Cancer is located at latitude . The Tropic of Capricorn is located at latitude . These two parallels are the northern and southern boundaries of a region known as the tropics . The Arctic Circle is located at latitude . The Antarctic Circle is located at latitude . These two parallels are the boundaries of the polar regions , which extend from these two parallels up to the poles . All places that are not in the tropics or polar regions are known as the . a One or more interactive elements has been excluded from this version of the text . You can view them online here ?

26 SCOTT CAMPBELL Visualize latitude and longitude on this spinning globe . Video by from . Latitude counterpart is longitude . While latitude has a naturally occurring reference reference point for longitude is arbitrary . The internationally reference point for longitude is based on Greenwich , England , home to Britain Royal Observatory . An imaginary line running from the north pole to the south pole , and passing through Greenwich , was established as the prime meridian in 1884 . A location longitude is determined by its position relative to Greenwich . If you were to start in Greenwich ( or any other location on the prime meridian ) and head due West , longitude would increase . When you got a quarter of the way around the world , you be at ( west ) longitude . When you got exactly halfway around the world from Greenwich , out in the middle of the Pacific Ocean , you arrive at longitude . The same is true if you head east from the prime meridian . If you left Greenwich heading due east , longitude would increase . When you got a quarter of the way around the world , you be at ( east ) longitude . Once again , when you were halfway around the world from Greenwich , you be at longitude ( which is the same as ) Chicago is located at about longitude , not quite a quarter of the way around the world from the prime meridian . Honolulu located at longitude , nearly halfway around the world from Greenwich . Heading the other way from the prime meridian , Baghdad is located at longitude , while Tokyo is located at longitude . Meridians of longitude are lines that run north and south on a map . They connect all points at the same longitude . All meridians run from pole to pole . Meridians are not parallel to one another . They are farthest apart at the equator , and get closer and closer to one another as they move into the higher latitudes . Meridians and parallels always interest one another at right ( angles . Ifyou look at world map , you might discover that a several ofthe rules of latitude and longitude do always hold true . The parallels and meridians do always intersect at right angles , the equator is not always longer than the other parallels , and the meridians might not converge at the poles . This is because the earth is a sphere . A globe will accurately reflect the rules of latitude and longitude , but a flat world map can not . Whenever you look at a world map , something is , by necessity , distorted . Direction , distance , shape , area , or sometimes a combination of all four , will always be distorted to some degree , since its Created by from Noun Project impossible to accurately display the whole ofthe spherical earth on a surface . For instance , compare and contrast the world maps pinning this paragraph . vo Created by ( from Noun Project EARTH MOVEMENTS The earth is continually making two major and rotation . First , the earth is revolving around the sun , once every days ( that extra quarter of a day is cashed in every four years for February ) The major effect of revolution is seasonality , which will be discussed below .

PHYSICAL GEOGRAPHY 27 The earth is also rotating on axis , turning eastward , and making one rotation per day . This causes the daily alternation of day and night , and causes the sun , the moon , and the stars to appear to rise In the east and set in the west . Rotation , coupled with the gravitational pull of the moon , also creates the alternation of high tide and low tide along the world coastlines . The rotation of the earth also causes the effect . As air masses travel through the atmosphere , they appear to change direction because they are passing over a spinning earth . In the northern hemisphere , the effect causes air masses to deflect to the right . In the southern hemisphere , air masses deflect to the left . The effect increases with the deflection is greatest at higher latitudes , and much less pronounced at lower latitudes . The effect is negated if an air mass is travelling straight down the equator . Effect . Photo by on . ELEMENTS OF Weather is the state of atmospheric conditions , such as temperature and precipitation , in a given place at a given time . Climate refers to the usual patterns of weather in a given place . Put another way , climate is the average of weather . Most climates can be reduced to three basic elements . The first element is a location is relatively hot , mild , or cold . The second element is a place is humid ( receiving a lot of precipitation ) arid ( receiving little precipitation ) or something in between . The third element of climate is the characteristics of temperature and precipitation typically vary over the course ofa year . Temperature There are a number of factors that affect the temperature of a location , but the most important factor is sunlight , or more specifically , the angle at which the sun rays strike the earth . Imagine you standing in a dark room , a few feet from a wall , holding a flashlight . Ifyou hold the flashlight perpendicular to the wall , so that the beam from the flashlight strikes the wall at a angle , it will create a small , intense pool of light . Now , ifyou tilt the flashlight to a angle , you notice that the pool of light on the wall gets bigger and dimmer . The same amount of energy is coming out of the flashlight , and it the same distance from the wall , but the change In angle has caused the light to spread out over a larger area , and decrease in intensity . Because the surface of earth is curved , the sun rays strike different parts of the earth at different angles . In the lower latitudes , closer to the equator , the sun rays strike the earth at , or something close to , a angle . The solar energy is concentrated , like our flashlight pointed directly at the wall , so temperatures are hotter . At higher latitudes , closer to the poles , the sun rays strike the earth at a lesser angle , and the effect is like our tilted flashlight . The sun energy is spread out over a larger area , the solar energy is diluted , so temperatures are lower . This is why Sweden is colder than Libya . Sweden is at a higher latitude , where light strikes the earth at a lesser angle . Libya is at a lower latitude , where the sunlight strikes the earth at a greater angle . This is also why Minnesota is colder than Illinois , why Illinois is colder than Tennessee , and why Tennessee is colder than Florida . The effect can be found at relatively small scales . On a typical day , Chicago northern suburbs will run a degree or two cooler than Chicago southern suburbs , all because of the angle ofthe sun incoming rays .

28 SCOTT CAMPBELL Seasons The major cause of seasonal changes is the inclination of the earth axis . The axis around which the earth rotates is not perpendicular to the plane in which it orbits the sun . The axis is tilted off center , like a buoy listing in a lake . As the earth makes its way around the sun , the northern hemisphere leans toward the sun for part of the year , and the southern hemisphere leans toward the sun the other part of the year . From March to September , the northern hemisphere is tilted toward the sun . As a result , the northern hemisphere stays illuminated for a longer period of each day , meaning that the days grow longer . The sun most direct rays also drift into the northern hemisphere , bringing greater heat . During these months , the northern hemisphere experiences spring and summer . At the same Created by Coquet time , the southern hemisphere is leaning away from the sun . Days from Noun Project , in the southern hemisphere get shorter , and temperatures decrease . From March through September , the southern hemisphere experiences fall and winter . The situation reverses itself from September to March , as the southern hemisphere tilts into the sun . The southern hemisphere has its longest and hottest days ofthe year , experiencing spring and summer . The northern hemisphere is now leaning away from the sun , experiencing shorter days and colder temperatures , passing through fall and winter . Seasonal variations tend to be the greatest at higher latitudes , while seasons do change much in the lower latitudes . Honolulu , for example , receives about thirteen hours of daylight in June , and about eleven hours in December , not a tremendous difference . Chicago , on the other hand , receives fifteen hours of daylight in June , and only nine hours of daylight in December , a much more noticeable difference . Anchorage , Alaska , receives nearly twenty hours of daylight , and only about five hours of daylight in December . Meanwhile , locations at the equator receive about twelve hours of daylight every single day of the year . Places in the Arctic and Antarctic circles receive hours of daylight in summer , and hours of darkness in winter . Precipitation , snow , sleet , an intensely complicated process . Very smart people with very expensive equipment still have trouble accurately predicting it . That said , the fundamentals of precipitation are relatively simple . Almost all precipitation processes begin with an air mass being lifted . As air rises , it begins to cool down . As air cools down , it approaches its dew point . If it does reach its dew point , the moisture in the air condenses to a liquid state , and a cloud is formed . If enough condensation occurs , then the waterfalls to the earth as precipitation . There are different mechanisms that cause the air to lift . Convectional precipitation occurs when the surface heats the air above it , causing that air to rise , and is most often associated with brief , isolated summer storms . Frontal precipitation ( sometimes called cyclonic precipitation ) occurs when air masses with different temperature characteristics collide with one another . A cold front is the leading edge of a cold air mass . If the

PHYSICAL GEOGRAPHY 29 dense cold air along this front collides with a warmer air mass , it forces the more buoyant warm air aloft . Cold fronts are often associated with violent storms . front is the leading edge ofa warm air mass . Ifthe buoyant warm air collides with a cooler air mass , it will often rise up over the dense cold air . orographic precipitation is associated with highland areas . As air masses strike a topographic barrier , like a mountain range , the air rises , which can create precipitation . The side of the mountain range where orographic precipitation takes place is known as the windward side . On the mostly dry continent of Australia , the east coast gets rain largely due to orographic precipitation . A side effect of orographic precipitation is the rain shadow effect . The leeward , or downwind side of the mountain range is often much drier than the windward side . This is because air masses often dump much of their available moisture on the windward side , but also because air masses are descending and the rain in Sydney , Australia . Photo by warming on the leeward side , and therefore are less likely to Nomad on . produce precipitation . The rain shadow effect can be found at relatively small scales , as is the case on many Caribbean islands , where the windward side of an island receives more precipitation than the leeward side . Or , it can exist on massive scales . In the American West , the Sierra Nevada , Cascade , and Rocky Mountains cast rain shadows that extend for hundreds of miles . Global Pressure Systems Variations in air pressure are the means by which air masses are moved about the earth . Air pressure is the amount of atmospheric , me my side mass exerted on the earth surface , and it varies from place to Mountains . Photo by thomas on . place . Put simply , if there is higher air pressure in Phoenix than in Des , then there is literally more air in Phoenix than in Des . Air flows from areas of high pressure toward areas of low pressure , and is manifested as wind . If the difference in pressure between two places is great , then the air will move faster , as in a gusty wind . If the difference in air pressure between to places is slight , then the air will move slowly , as in a gentle breeze . Because air moves away from areas of high pressure , reducing the chances of collision and lifting , those places tend to be relatively dry . Because air is drawn toward areas of low pressure , increasing the chances of collision and lifting , those places tend to be relatively wet . In most places , air pressure shifts constantly , which is why meteorologists keep an eye on the barometer , which measures air pressure . A rising barometer decreases the likelihood or precipitation . A falling barometer increases the likelihood of precipitation . On the global scale , there are a few major pressure systems that have a tremendous impact on the weather . The first are subtropical highs . The subtropical highs are a series of systems that are found at approximately and 30 latitude . These massive ridges of high pressure cause dry conditions wherever they are found . A quick look at a map of the world most significant deserts reveals that many of them are located at about latitude , such as the Mojave , Sahara , Arabian , and Great Indian Deserts , or at about

30 SCOTT CAMPBELL 30 latitude , such as the , and Australian Deserts . Note that the subtropical highs are a periodic sequence of pressure systems , not a continuous belt of high pressure . Not all places at latitude are under subtropical highs . New Orleans , for example , is at that latitude , and is much of the year . The subtropical highs also generate enormous amount of wind . They push air off toward the higher latitudes , creating the . The are located between approximately and 60 north and south latitude . As the subtropical highs push air poleward , the effect causes them to bend to the right in the northern hemisphere , and to the left in the southern hemisphere . The result is a circulation in both the northern and southern from west to east . Much of the continental United States , southern Canada , Europe , and the Russian Domain receive their weather from the west , which has a significant impact on climate patterns there . The subtropical highs also push air to the lower latitudes . In the northern hemisphere , these winds bend slightly to the right because of the effect , creating the northeast trade winds . In the southern hemisphere , these winds bend slightly to the left , creating the southeast trade winds . So , in the southern tropics , air I tends to flow equatorward from the southeast . In the northern tropics , air tends to flow equatorward from the northeast . The I trade winds collide near the equator , in a region known as the intertropical convergence zone , or . The collision of these warm , often very moist tropical air masses creates extremely wet as some of the world great deserts are associated I with the subtropical highs , many of the world great rainforests are found near the equator , such as the Amazon rainforest , and the Created by rainforests of central Africa and southeast Asia . from Noun Project Two more systems , the polar highs , are located In the Arctic and Antarctic regions , creating very dry conditions . Antarctica , although covered in snow and ice , is technically a desert , receiving very little annual precipitation . The polar highs push air the lower latitudes , and the effect deflects them to the right in the northern hemisphere , and to the left in the southern hemisphere . In the polar , air circulates from east to west , usually above north and south latitude . All of these pressure features shift seasonally . When it is summer in the northern hemisphere , they slide north . When it is summer in southern hemisphere , they slide south . For some places , this can cause significant changes in the weather . Los Angeles , for example , spends much of the year under a subtropical high , and receives very little precipitation . In the wintertime , though , that subtropical high shifts south . The also shift south , and carry a significant amount of moisture offthe Pacific Ocean , bringing rainy winters to Los Angeles . Other Climate Factors Elevation has a significant impact on temperature . That is discussed in Chapter 68 . The presence of absence or large bodies of water can also have a tremendous impact on temperature . The difference between maritime and continental climates is discussed in Chapter 41 . CLIMATE CHANGE The earth climate has been changing for millions of years , with temperature periodically increasing or

PHYSICAL GEOGRAPHY 31 decreasing . Fifteen thousand years ago , much of the earth was covered in massive sheets of ice , so it is obviously much warmer now than it was then . Climate change is a natural process . That said , when people use the term climate change today , they are usually referring to anthropogenic climate change , or climate change caused by human activity . The earth is currently in a warming phase , but a preponderance of evidence suggests that humans are accelerating that warming at an alarming rate . Increased planetary temperatures are associated with the greenhouse effect . That term takes its name from constructed primarily of glass that are utilized to grow and sustain plants in cold climates . The glass in a greenhouse allows vital sunlight to reach plants , but prevents heat from escaping the building . If you do own a greenhouse , but do own a car , you have probably experienced the greenhouse effect . lfyou park your car in a lot on a sunny summer day , and return to it an hour or two later , you will likely find that the interior ofyour car is extremely hot . This is because sunlight , with its relatively short wavelength , has easily passed through the glass in your car . As your car absorbs that energy , it begins to radiate it back thermal radiation , or heat . Created by Because thermal radiation has a longer wavelength , it has more from Noun Project trouble passing back through the glass of your car . So , light continues to pour in , but relatively little heat escapes , and the inside of your car gets hotter and hotter . The same thing happens in the atmosphere . Instead of glass , there are greenhouse gasses , like carbon dioxide and methane . These gasses allow sunlight to pass through the atmosphere with relative ease . When the earth radiates heat , it has trouble escaping through the greenhouse gasses . So , the earth atmosphere stays relatively warm . Like climate change , the greenhouse effect is a natural phenomenon , and is , in fact , vital for life on earth . Without the greenhouse effect , the earth would quickly shed its heat , and would be a very cold place . Humans did not create the greenhouse effect , but we are enhancing it . By various means , but primarily through the production and consumption of fossil fuels , humans are pumping large volumes of greenhouse gasses into the atmosphere . In doing so , we are the greenhouse effect . The more greenhouse gasses we put in the atmosphere , the more heat is trapped , and the warmer the earth gets . Climate change has varied spatially and seasonally . Some places are warming faster than others , and some years are hotter than others , but the earth overall temperatures are certainly increasing . Of the ten hottest years on record , nine have occurred within the last decade , and all of them have occurred within the last fifteen years . Polar regions are being dramatically altered , since ecosystems based on ice and snow are going to be deeply impacted by even the slightest temperature increase . Precipitation patterns are being amplified . Wet areas are getting wetter , while dry areas are getting drier , wreaking havoc on agriculture in many parts of the world . Sea levels are rising . While it is unlikely that West Virginia will be oceanfront property anytime soon , coastal areas are experiencing increased erosion and dramatic flooding . Plant and animal extinctions are on the rise , as many species have trouble adjusting to the new normal . Climate scientists vary in their predictions for the future , but they generally range from deeply concerned to extremely gloomy . The vast majority of scientists agree that humans must find a way to curb greenhouse gas emissions to prevent a global environmental catastrophe .

32 SCOTT CAMPBELL Plate Tectonics The outer crust of the earth is not one solid piece , but rather a collection of interlocking tectonic sort of jigsaw puzzle . These tectonic plates can and do move independently of one another , albeit at a very slow pace . Tectonic plates generally move about as fast as your fingernails grow . Given millions of years , though , the movement of these plates can dramatically rearrange the world map . Brazil used to border , Portugal used to border , India used to border Australia , and the United States used to border Morocco ( their territories , that was , of course , millions of years before these countries actually existed ) Plate tectonics play a major role in global and natural hazards . There are a few different types of tectonic boundaries , such as transform boundaries , where one plate is sliding alongside another one , and divergent boundaries , where one plate is moving away from another one . Of greatest interest to world regional geography is the convergent boundary , where one plate is colliding with another . The most important result of a convergent boundary is folding . Imagine a throw rug on a floor . If you took a push broom and shoved it against the edge of that rug , the rug would wrinkle up , folding into ridges and valleys . The same thing can happen to the surface of the earth . About 80 million years ago , India began to collide with Asia . Using our metaphor , India would be the push broom , and Asia would be the rug . As a result of this collision , the and many other mountain ranges folded upward , while valleys and basins sank downward . This of the fabric of Asia is ongoing , and its effects have been far flung . India collision with Asia has caused the upward folding of mountain ranges as far Image by , on . away as Siberia . For a visualization of this imaginative metaphor , look here . For an excellent illustration of tectonic plates , go to . Convergent boundaries are also associated with major natural hazards . All around the Pacific Ocean is a zone known as the Ring of Fire . The tectonic plates beneath the eastern Pacific are moving east , colliding with the plates that make up the Americas . The tectonic plates beneath the western Pacific are moving west , colliding with the plates that make up East Asia . This collision has not only created numerous mountain Photo by Scott ranges along the Pacific Rim , such as the Andes of South America , but also volcanoes and earthquakes . As one tectonic plate slips below another process known as subduction tremendous pressure involved melts the rock of the plate . Some of the lava , ash , and gasses released by the melting plate find their way to the surface in volcanic eruptions . The Ring of Fire includes scores of volcanoes , such as . Fuji in japan , in the Philippines , and . in the United States . And every time these tectonic plates slip , the surface shudders . If they make a significant movement , the tremors can amplify into massive earthquakes . The entire Ring of Fire is highly susceptible to this hazard . japan , Mexico , Peru , Ecuador , the United States , and the Philippines are some ofthe most countries on the planet .

PHYSICAL GEOGRAPHY 33 Erosion and Deposition Tectonic plates are not the only forces that shape the world landscapes . Two other important and constantly reshaping the face of the earth . Erosion refers to forces that remove material from a landscape . Deposition refers to those same forces depositing that material elsewhere . Running water , freezing and thawing , gravity , coastal waves , wind , and glaciers all pick up bits of earth , both large and small , and deposit them someplace else . A river erodes its banks , ice crystals and plant roots break up rocks , gravity carries material downslope , waves beat at seaside cliffs , wind carries away soil , and glaciers scour out lakes and valleys . And then rivers deposit sediment in deltas and , rocks come to rest in a valley floor , cliffs crash into the sea , sediment settles onto the ground , and glaciers melt , leaving their eroded material behind . Another name for this process is weathering , and different landscapes are at different stages of weathering . Some landscapes are at early stages of weathering , meaning that they are relatively new , and that erosion and deposition have had much time to alter them . Other landscapes are at very advanced stages of weathering , meaning that they are quite old , and have been deeply altered by erosion and deposition . For example , the Great Lakes , and much of landscape of the upper Midwest , were formed by glacial erosion and deposition about years ago . That relatively new . A few hundred miles away are the Highlands of Missouri and Arkansas , deeply eroded hills that are more than 200 million years old . Did You Know ?

Many people know that the effect causes toilets flush clockwise in the northern hemisphere , and counterclockwise in the southern hemisphere . Unfortunately , many people are wrong . Toilets do not flush different ways in the two hemispheres , and whichever direction they flush , it has nothing to do with the effect . So , if planning to fly to Australia just to watch the toilets flush the other way , save your money . A fascinating book about the importance of longitude in the Age of Exploration is Longitude by . CITED AND ADDITIONAL BIBLIOGRAPHY alan , thomas . 2014 . Eastern Washington . Generic ( 2016 . Spinning Globe . Nomad Tales . 2010 . Caught in the Rain . Generic ( SA ) 2017 . Effect . 90 . Attribution Generic ( BY )