Flash Flood! sections When cool, dry air meets warm, moist air 1 Earth’s Atmosphere Lab Visualizing a dramatic things can happen. Many desert Temperature Inversion environments are familiar with flash floods that can result from such an event. Dry river 2 Weather beds can suddenly become raging torrents of 3 Climate water, rocks, and mud. 4 Earth’s Changing Climates Science Journal In your Science Journal, describe Lab Investigating some of your observations of severe weather. Hypothesize Microclimate what might cause these weather events.
516 Byron Aughenbaugh/Getty Images Start-Up Activities
Weather and Climate Make the following Foldable to com- pare and contrast the character- Atmospheric Pressure istics of weather and climate. Changes in atmospheric pressure are involved in producing winds and weather. You may STEP 1 Fold one sheet of paper lengthwise. not be aware of how much pressure the atmosphere exerts, but you can see it in this Lab.
STEP 2 Fold into thirds. 1. Fill a glass to the brim with water. 2. Place a piece of thick paper or cardboard on top. 3. Hold the paper or cardboard securely to the brim of the glass. Turn the glass STEP 3 Unfold and draw overlapping ovals. upside down. Cut the top sheet along the folds. 4. Release your hand from the paper 5. Think Critically What keeps the paper or cardboard against the brim of the glass and the water from flowing out? STEP 4 Label the ovals as shown.
Weather Both Climate
Constructing a Venn Diagram As you read Preview this chapter’s content the chapter, list the characteristics unique to and activities at weather under the left tab, those unique to cli- gpescience.com mate under the right tab, and those elements common to both under the middle tab.
517 Byron Aughenbaugh/Getty Images Earth’s Atmosphere
Reading Guide
New Vocabulary ■ Describe the composition of the Heat and water are essential for life troposphere atmosphere. on Earth. • temperature inversion ■ Explain how the atmosphere is • greenhouse effect heated and include the role of Review Vocabulary • latent heat land surface and water. nucleus: a central point about • ■ Describe Earth’s system of water which concentration or accretion cycling. takes place
Atmospheric Composition You probably never think about the air you breathe. Your body uses only oxygen, but air is a mixture of gases. Nitrogen is the largest component with 78 percent and oxygen is next with 21 percent by volume. Most of the remaining one percent is the inactive gas argon and water vapor in varying amounts. The small remaining portion is a mixture of trace gases, so called because they are present in such small, barely detectable amounts. For example, carbon dioxide makes up only about 0.03 percent, and the other trace gases—methane, nitrous oxide, and ozone—together make up less than 0.001 percent of the atmosphere. Still, these trace gases are critical for life on Earth.
What are the trace gases?
Figure 1 In northern latitudes, Biological Processes Living organisms produce trace carbon dioxide concentration gases, except ozone. Cellular respiration by organisms produces increases during summer and water vapor and carbon dioxide (CO ). Photosynthetic organ- decreases during winter. 2 isms use carbon dioxide and produce almost all the oxygen in the atmosphere. Organisms alter atmos- Comparison of CO2 Concentration to Time of Year and Latitude pheric CO2 concentration at various lati- tudes throughout the year, as shown in 360 Figure 1. Microorganisms in swamps, 350 rice paddies, and soil produce nitrogen
340 90N (ppm) and methane. The microorganisms in the
330 0 Concentration 1982 digestive tracts of animals such as ter-
2 1983 1984 -90S
CO Latitude mites, cows, and sheep produce methane.
518 CHAPTER 17 Weather and Climate Formation of the Atmosphere Earth’s early atmosphere contained mostly hydrogen and helium. These gases were lost and were replaced by gases from volcanic eruptions, including water vapor and CO2.Oxygen from photosynthetic marine organisms accumulated in the atmosphere and intense solar Visualizing radiation converted some of it into ozone. The ozone layer Convection shielded Earth from harmful ultraviolet rays. This allowed pho- Procedure tosynthetic organisms to emerge on land, where they produced 1. Place an ice cube in the more oxygen. center of a beaker. Some scientists think it took millions of years for our 2. Add room-temperature atmosphere to reach its current state—a delicate equilibrium water until the beaker is between processes producing and destroying atmospheric three-fourths full. 3. Place one drop of food gases. Unfortunately, human activities might be threatening coloring on the surface of this equilibrium. the water. 4. Observe what happens. Atmospheric Structure Analysis Earth’s atmosphere extends more than 1,000 km above Earth’s 1. Describe what happened surface. Most of our weather takes place within the troposphere, to the color. 2. Explain why this occurred. a layer extending 30 km above Earth’s surface. In this layer, as shown in Figure 2, temperature normally decreases with height. Sometimes, however, temperature increases with height. This is called a temperature inversion. When this happens, the air is very stable—it resists the rising motion needed to form clouds or to disperse air pollution.
The Stratosphere Above the troposphere is the stratosphere, which is extremely dry and rich in ozone. Here, temperature always increases with height, creating a permanent temperature inversion. The place where this tem- perature inversion begins is called the tropopause. It acts like a lid that Temperature Change with Height keeps air in the troposphere from 200 rising into the stratosphere. The uppermost layers, the mesophere and thermosphere, are very low in density and do not affect weather.
100 75 Figure 2 Temperature decreases Height (km) Ozone layer with height in the troposphere up to 50 the tropopause. Above the tropopause, 25 Stratosphere Tropopause temperature increases with height in Troposphere 0 the stratosphere. –120 –60 0 60 120 180 300 400 600 800 Identify The ozone layer is found in Temperature (˚C) which atmospheric layer?
SECTION 1 Earth’s Atmosphere 519 Heating the Atmosphere The energy that heats the atmosphere ultimately comes from the Sun. In the stratosphere, solar rays split oxygen molecules into single atoms. The oxygen atoms then react with other oxygen molecules, forming ozone. Ozone absorbs nearly all of the Sun’s ultraviolet radiation. This absorption by ozone is why temperature increases with height in the stratosphere. The remaining solar rays pass to Earth’s surface where they are either absorbed or reflected back to the atmosphere. As Earth’s surface is heated, it emits long-wave, infrared radiation. Trace gases, such as carbon dioxide and water vapor, absorb long wavelengths and re-emit some of them back to Earth’s surface. The term greenhouse effect refers to this re-emission of infrared radiation back to Earth’s surface, as shown in Figure 3. Oxygen and nitrogen absorb little radiation and contribute little to atmospheric heating. Although water vapor and trace gases make up less than 0.03 percent of the atmosphere, they Figure 3 Trace gases absorb are strong absorbers and heat the atmosphere the most. infrared radiation and are heated. Conduction, convection, and latent heat also contribute to These gases then re-emit infrared heating Earth’s atmosphere. Latent heat is heat energy released in all directions, sending part of it or absorbed during the phase changes of water, such as evapo- back to Earth’s surface. rating water or melting snow. It is released to the atmosphere Infer How does this compare to when water vapor condenses as clouds. being covered by a blanket at night? A Varied Surface Earth’s surface is not uni- Sun Ultraviolet form and therefore, heats the absorbed by atmosphere unevenly. Snow, ozone ice, water, vegetation, and Visible light bare soil reflect different reflected by Infrared emitted amounts of solar radiation clouds by atmospheric CO and H O back to space and heat at dif- 2 2 ferent rates when they absorb radiation. For example, dry land heats rapidly and emits much radiation to the atmos- phere. In contrast, water tem- perature changes slowly and Emitted infrared stores heat, releasing it at a by Earth later time. This uneven pat- tern of surface heating gives rise to pressure differences and wind.
520 CHAPTER 17 Weather and Climate Water in the Atmosphere Uneven heating has another effect. It produces currents of air that carry water vapor aloft and form clouds. Air generally rises over warm surfaces and sinks over cold surfaces. Many birds and hang gliders soar on these warm currents, called thermals. As air rises, it expands and cools. To form clouds, moist air must rise high enough to cool to its dew point. At this tempera- ture, air is saturated and water vapor condenses to form cloud droplets. Small particles in the air, called condensation nuclei, trigger this process. When present in high quantities, such as in dust or polluted city air, these nuclei can trigger condensation in unsaturated air. This is how smog forms.
Explain how smog forms.
Precipitation Cloud formation is the first step in the precip- itation process. Two basic cloud types are the puffy cumulus type and the flat, elongated, stratus type. Cumulus clouds form from rising air parcels. If they produce rain, it is usually only brief showers. Stratus-type clouds form mainly when layers of air rise gently. They usually produce drizzle or long-lasting rain. Many in-between forms of clouds exist, depending on how sta- ble the air is and how high in the atmosphere the clouds form. You can see some of these types in Figure 4. One type you might recognize is the cumulonimbus, or thunderhead. This cloud forms from unstable air and usually brings intense rain. Figure 4 Clouds affect atmos- Cloud droplets are so small that they might be kept aloft by pheric heating by absorbing or turbulence or evaporate before reaching Earth. For precipitation blocking solar radiation and trap- to occur, droplets must grow large. Growth can occur when ping Earth’s radiation. Cloud cover droplets collide and combine. This is called warm rain. Droplets also helps to reduce daytime tem- grow faster when they combine with ice crystals high in the perature and increase nighttime atmosphere. This is called cold rain. temperature.
Cirrus High Clouds Height 12 km Cirrocumulus (about 40,000 ft) Cirrostratus 6 km Middle Clouds Altocumulus (Anvil head) (about 20,000 ft) Altostratus 3 km Low Clouds Clouds with (about 10,000 ft) vertical development Cumulonimbus 1.5 km Cumulus Stratus Cumulus (about 5,000 ft) of fair Nimbostratus Stratocumulus weather (Ground) 0
SECTION 1 Earth’s Atmosphere 521 Figure 5 Earth’s continual cycling of water strongly affects weather and climate.
Plants Transpiration is the loss of water through pores in the leaves of plants. More than 90 per- Global Water Cycle cent of the water that enters a plant returns to Precipitation, runoff, storage, and evaporation make up the the atmosphere through global water cycle, shown in Figure 5. Plants are an important the process of transpira- part of the water cycle. They affect absorption and runoff and tion. Research how return water to the air by evaporation from their surfaces. humidity and air temper- People affect the water cycle in many ways. They use ground- ature affect transpiration rates in plants. Share water for irrigation or pump it from wells. They replace forests your findings with your with agricultural fields and pave land to build cities. Many of class. these changes have reduced water quality and resources. Conserving water resources requires careful planning.
Summary Self Check Atmospheric Structure 1. Describe how temperature of the atmosphere changes The stratosphere and the troposphere are two with height and explain why. • lower layers of Earth’s atmosphere. Most 2. Explain the greenhouse effect. weather takes place in the troposphere. 3. Explain why small changes in the amount of trace Atmospheric Heating gasses are so important in heating Earth’s atmosphere. Most solar radiation first heats Earth’s surface, 4. Identify what must happen before rain can occur. • which then heats the atmosphere. 5. Compare and contrast cumulus and stratus clouds. Characteristics of the land surface greatly 6. Think Critically How might changes on Earth’s surface, • influence atmospheric heating. such as deforestation, have an effect on weather? Water in the Atmosphere Cloud formation generally requires moist air, 7. Use Percentages If the southern hemisphere contains • rising and cooling, and condensation nuclei. 10 percent land and the northern hemisphere contains Water is cycled through Earth’s system by pre- roughly 40 percent land, what percent of Earth is land? • cipitation, runoff, storage, and evaporation.
522 CHAPTER 17 Weather and Climate More Section Review gpescience.com Visualizing a Temperature nversion
Normally temperature decreases with increas- 2. Add one to two drops of food coloring to the ing altitude in the troposphere. Sometimes water in the 10-mL beaker and let it stand near the ground, a temperature inversion at room temperature. occurs and air becomes very stable and resists 3. Heat 250 mL of water in the 500-mL beaker rising. This can result in fog or smog in cities. to near boiling. Will a liquid behave in the same manner as the 4. Hold the ladle at the surface of the chilled atmosphere? water. Very slowly pour all the heated water into the ladle and allow it to slowly flow out of the ladle onto the surface of the chilled Real-World Problem water. You should have a bottom layer of How can you visualize what happens during a cold water and a top layer of hot water. temperature inversion? 5. Use the long-stem dropper to inject a few Goals drops of the colored water from step 2 into ■ Make a model that demonstrates a the cold water in the 10-mL beaker. temperature inversion. ■ Apply what you observe to explain what happens in the atmosphere during a Conclude and Apply temperature inversion. 1. Describe what happened to the colored water. Materials 10-mL beaker containing 2–3 mL water 2. Explain why this happened in terms of the 500-mL beaker containing 250 mL water temperatures of the water layers. 1,000-mL beaker containing 750 mL water 3. Infer how this is related to temperature food coloring ladle inversions in the atmosphere. long-stem dropper thermal mitt freezer hot plate Safety Precautions
Write a brief paragraph describing your experiment and your observations. Include Procedure a labeled diagram showing the temperature 1. Chill 750 mL of water in a 1,000-mL beaker layers and explain what happened to the to near freezing. colored water.
LAB 523 Weather
Reading Guide
New Vocabulary ■ Explain what causes Earth’s Weather affects the health, life, and westerlies major wind and pressure systems. livelihood of everyone on Earth. • jet stream ■ Describe typical daily weather • subtropical high patterns around lows and fronts. • weather front ■ Describe the most important Review Vocabulary • storm systems and forms of gradient: the rate of change of a severe weather. quantity with distance
Atmospheric Pressure Although you usually are unaware of it, the atmosphere presses down on you with a pressure equivalent to one kilogram per square centimeter. This pressure is caused by gas molecules moving and colliding with each other and any surfaces they touch. Because the number of air molecules decreases as altitude increases, pressure always decreases with altitude. This is why air is said to be thinner in the upper atmosphere. The number of air molecules, including oxygen, decreases in proportion to pres- Figure 6 In the northern hemi- sure. This is why jet aircraft cabins are pressurized and why sphere, four major pressure belts climbers can get mountain sickness at altitudes over 3,000 m. produce three major wind belts. Infer How does pressure affect Global Winds and Pressure Systems Weather patterns wind direction? result from complex global patterns of wind and pressure. Figure 6 shows a simplified picture of the Earth’s Polar easterlies Polar high major pressure belts that give rise to major wind Sub-polar low belts. The most important of these are the Westerlies H L L Subtropical westerlies—winds that blow from the west in the Northeast high middle latitudes—and the trade winds, which trades H HH blow from the east, in the tropics. Two factors produce these global patterns— Equatorial L LL unequal heating between the equator and poles low and the rotation of Earth. Warm air rising near Southeast H HH the equator and sinking over the poles creates trades general north-south wind circulation. Earth’s L L rotation produces an east-west deflection of this Westerlies H general circulation pattern.
524 CHAPTER 17 Weather and Climate Jet Streams Imbedded in these wind systems are fast and powerful jet streams that control many weather processes, such as storm development. Most important for the United States is the polar front jet stream, a wind maximum in the westerlies located about 12 km above the surface. Its speeds can exceed Modeling the Coriolis 500 km/h. Major storm tracks follow it as it moves north and Effect south with the seasons. Procedure 1. Put a large, round piece High and Low Pressure Systems of cardboard or paper on a turnable surface such as The large-scale weather systems that have the most effect on a turntable. the United States are the subpolar lows, westerlies, and the sub- 2. Hold a ruler just above the tropical highs. Subtropical highs are relatively stable belts of high diameter of the cardboard. pressure near latitudes of 30°. In contrast, sub-polar lows and the 3. Ask someone to turn the westerlies tend to meander as smaller cells of high and low pres- surface while you draw a sure develop. The lows generally develop from a disturbance in line across the turning cardboard with your pen the polar front jet and move eastward with the jet stream. or pencil against the ruler. Specific patterns of weather are associated with high and low 4. Repeat step 3 but turn the pressure cells because of the way air flows around them. In the surface in the opposite northern hemisphere, winds blow counterclockwise around lows direction. and clockwise around highs, as shown in Figure 7. In the south- Analysis ern hemisphere, the directions reverse. Lows are associated with 1. Compare the outlines rainfall and storms, and highs with calm winds and clear skies. drawn on the cardboard. 2. Explain how these outlines Coriolis Effect Airflow around low or represent the Coriolis high pressure areas results from the net effect. forces acting on the air. First, the pressure gradient pulls the air toward low pressure. Then an apparent force, called the Coriolis effect, deflects the air to the right in the northern hemisphere. When these forces are balanced, air flows perpendicular to lines of equal pressure. Near the surface, friction slows air and modi- fies its direction, turning it slightly toward low-pressure centers and slightly away from high-pressure centers. This causes air to rise in the center of lows and to sink in the center of highs.
Risingair Sinking air
Figure 7 At Earth’s surface in the northern hemisphere, air moves counter- clockwise toward low pressure and L H clockwise from high pressure. Infer How does air move when it is high above Earth’s surface, above each pressure system?
SECTION 2 Weather 525 Air Masses and Weather Fronts Weather around low-pressure cells is produced by interac- tion of air masses—large units of air with relatively uniform moisture and temperature. These form when air remains sta- tionary for a time, such as in regions of high pressure. The air then takes on the characteristics of the surface. Air masses can be polar or tropical and continental or maritime. Continental air originates over land. It is relatively dry and can be extremely cold or extremely warm. Maritime air masses are moist because they originate over the oceans. The maritime air masses affect- ing the United States come from the Atlantic Ocean, the Pacific Ocean, or the Gulf of Mexico. Air masses interact in zones called weather fronts, as shown in Figure 8, which are associated with low pressure systems. Warm and cold fronts create different types of precipitation. In a warm front, warm air rises gently above the cold air, usually forming layered, stratus-type clouds or fog—a cloud with its base on the ground. Most layered clouds produce only drizzle or Figure 8 The symbols shown steady rain. In a cold front, cold air pushes the warm air aloft in below each of these weather fronts a random and chaotic fashion forming cumulus clouds. These are used by meteorologists to often produce showers and thunderstorms. represent the respective fronts on weather maps. What are weather fronts?
Warm air
Warm air Cold air Cold air
Cold front Warm front
Warm air
Warm air Cool air Cold air Cold air
Stationary front Occluded front
526 CHAPTER 17 Weather and Climate Severe Weather The continental United States is prone to severe weather because of the extreme temperatures of warm and cold air masses and the availability of moisture from tropical oceans. Such conditions lead to severe thunderstorms, hurricanes, tor- nadoes, and violent wind storms called downbursts.
Thunderstorms Recall that cumulonimbus clouds formed from unstable air produce thunderstorms. A typical cumulonim- bus cloud has ice crystals near its top, as shown in Figure 9. Sometimes these ice crystals act as nuclei to trigger further growth of cloud droplets, and turbulence adds layers of ice dur- ing many cycles of sinking and rising. This forms hail. Hailstones can grow to the size of softballs and can cause extensive damage to crops and structures. Figure 9 When hailstones fall, they are repeatedly caught in Downdrafts and Squalls The force of the falling precipi- updrafts, coated with moisture, tation in a thunderstorm may pull with it cold air bursts from and frozen. This gives them a higher in the cloud. This is why the air often feels cool after a layered, onionlike appearance. thunderstorm. This sinking current of cold air is called a Infer Why does this cumulonimbus downdraft. When a downdraft hits the surface with particu- cloud have an anvil-shaped top? larly strong force, it spreads out in a series of windy gusts called squalls. Upper air flow In arid regions, squalls produce dust storms.
Downbursts Cold air downdrafts 12 km Anvil top can produce even more severe forms of weather. One example of an extreme form of wind shear is a downburst. Here, cold air descends from a thunderstorm and hits the ground. When it hits the ground, it bursts outward like the spokes on a Updraft wheel. The rapid change in wind speed and/or direction that a down- Downdraft burst causes can be dangerous for aircraft during both take-off and Storm travel landing. The winds that result from downbursts can be as high as 260 km/h. Fortunately, automated warning systems now alert pilots to look for signs of downbursts when approaching an airport.
SECTION 2 Weather 527 Tornadoes and Hurricanes Two types of violent wind storms that differ greatly in their origins and effects are tornadoes and hurricanes. Tornadoes are intense, short-lived, Topic: Hurricane Tracking localized storms in the mid-latitudes. They originate in cumu- Visit gpescience.com for Web lonimbus clouds under special conditions. Typically, tornadoes links to information about that occur in the United States form when dry air from the hurricanes and hurricane tracking. deserts of Mexico and the southwest overrides warm, moist air Activity Research six hurricanes. from the Gulf of Mexico. This happens frequently in the Great Make a table that lists how each Plains, the lower midwest, and parts of the south, as shown in was tracked as a tropical depres- Figure 10. In the south, they often accompany hurricanes. sion and then as a hurricane. A twisting, funnel-shaped tornado cloud can move across land at a speed of around 50 km/h creating a path 150 m wide Figure 10 Texas, Oklahoma, and 10 km long. Intense, circular winds in the funnel can reach and Kansas frequently experience speeds up to 400 km/h. The extreme low pressure at the center tornadoes. can result in more damage than that from the wind. Hurricanes are tropical storms that cover vast 10 10 Fewer than areas and last for days. Those affecting the United 50 ten 10 10 States often form as tropical depressions over the 50 warm waters of the southern Atlantic off the Fewer 100 than coast of Africa. When winds exceed 118 km/h, the ten 10 10 200 storms are called hurricanes. A typical hurricane 10 consists of vast cloud bands that spiral inward 300 100 toward the clear center, called the eye. Scientists Scale 100 50 0 500 mi 10 50 often fly into the eye to study the storm. Western 0 1000 km 100 Pacific hurricanes are called typhoons. 50 50
Summary Self Check Global Wind and Pressure Systems 1. Explain how Earth’s rotation affects winds. • Four major pressure systems produce three 2. Compare and contrast tornadoes and hurricanes. major wind systems in each hemisphere. 3. Infer the wind directions around a high in the southern High and Low Pressure Systems hemisphere. Air flows counterclockwise around lows 4. Describe common differences between continental air • and clockwise around highs in the northern masses and maritime air masses. hemisphere. 5. Compare and contrast warm fronts and cold fronts. • Air rises in the center of lows and sinks in the 6. Think Critically If the polar front jet stream were to center of highs. move southward over the U.S., what other weather Weather Fronts and Severe Weather systems are likely to be affected? • Air masses interact at weather fronts. Warm fronts are associated with stratus-type • clouds and cold fronts with cumulus-type clouds. 7. Use Percentage A tornado watch was issued on 25 days during one year in a midwest city. What Severe weather includes hurricanes, torna- percent of the year does this represent? • does, and downbursts.
528 CHAPTER 17 Weather and Climate More Section Review gpescience.com Climate
Reading Guide
New Vocabulary ■ Describe what determines Climate affects the way you live. • biosphere climate. • continental climate ■ Explain how latitude, oceans, and • maritime climate other factors affect the climate of Review Vocabulary lee rain shadow a region. • sea breeze ■ Classify climate systems. boreal: relating to northern regions • ■ Describe climate distribution over the United States.
Climate and Weather What is the climate where you live? Traditionally, climate means the long-term average of weather conditions—wind, temperature, precipitation, moisture, and other aspects of Figure 11 All of the five spheres weather. Climate also describes the annual variations of these shown below interact. Each sphere conditions and their extremes. causes changes in, and is changed Averages of data collected monthly over 30 years or longer are by, the others. used to define climatic normals. These normals do not describe Research What does the prefix usual weather conditions of an area, but are only averages of con- cryo- mean? ditions measured at one local site. For example, the conditions in a city might vary from what is meas- Space ured at an airport weather station outside the city.
Climate System Climate is best considered as Atmosphere part of the whole Earth system. This biogeophys- ical system can be visualized as five spheres that interact to create the environments in which we live, as shown in Figure 11. The atmosphere Biosphere Cryosphere includes the air around us. The biosphere is everything organic, including plants, animals, and humans. The hydrosphere is liquid water in oceans, lakes, rivers, soil, and underground. The cryosphere is frozen water in snow, ice, and gla- Hydrosphere Lithosphere ciers. Finally, the lithosphere is the solid Earth, including its soil, rocks, and mantle.
SECTION 3 Climate 529 Sphere Interactions Gases, water, soluble materials, energy, and particulates are exchanged among these spheres. Each sphere affects all the other spheres. For example, volcanic erup- Topic: World Climates tions transfer gases and particles from the lithosphere to the Visit gpescience.com for Web atmosphere. The atmosphere provides and regulates the links to data on mean annual amount of water in the hydrosphere and cryosphere, and pro- temperature and rainfall of vides water, carbon, and oxygen for the biosphere. Through world cities. winds, atmosphere causes erosion, creates soil, and absorbs and Activity Use a world atlas, emits energy from the Sun. When you consider all these com- globe, or large classroom map to plex interactions, you can see why it’s better to define climate as find a city corresponding to each of the eight climate divisions the average weather conditions, their variability and causes, and shown in Figure 17. inter-relationships of many individual systems within the global Earth system. One example how such systems are inter-related is illustrated in Figure 12. What causes climate? Latitude is the primary factor that determines climate at a given location. The amount of radiation received from the Sun and the prevailing circulation features depend on latitude. Other factors are location near high mountains or on the east or west sides of a continent and distance from major bodies of water.
Causes of Mean Temperature The amount of solar radi- ation received and surface temperatures vary greatly from the equator to the poles. In the winter, the amount of solar radiation varies, because of the low angle at which it strikes Earth. As a result, temperatures decrease rapidly with increasing latitude. The high reflectance, or albedo, of snow and ice in high latitudes adds to this decrease. In summer, temperature decrease is less pronounced as sunlight strikes at a higher angle and periods of daylight are longer. The temperature patterns over the United States illustrate this, as shown in Figure 12. The strong temper- ature gradients in winter and spring help to create storms and severe weather.
5 -35 -30 -25 10
Figure 12 Lines drawn on a –20 15 –15 weather map that connect points –10 20 –5 15 of equal temperature are called 0 5 10 20 25 15 30 isotherms. 20 25 Infer Why are warmer tempera- tures shifted northward in July? January July
530 CHAPTER 17 Weather and Climate NGSVISUALIZING TITLE EARTH’S BIOGEOPHYSICAL SYSTEM
Figure 13
he Namib desert illustrates the Tinterconnectedness of climate, geology, plants, and animals. It is Transverse dunes created by high pressure, form perpendicular wind, and cold ocean to the wind. currents along the west coast of southern Africa. The desert is constantly reshaped by the wind. Transverse dunes show that the wind blows in one preferred direction. Dunes also begin when isolated plants trap sand. However, most deserts are not covered with sand dunes—they are made of stony pavement left behind when wind strips the desert surface. Star-shaped dunes Winds and water remove the finer surface form when winds materials, leaving stones behind. This process are variable. is called deflation.
Dense coastal fog forms when the air above cold ocean currents interacts with moist desert air. Although deserts may appear to be dry, the air above ground contains lots of moisture. Condensation from fog produces fog-water, which drips into desert pavement and dissolves rocks, forming new sediment. It also forms small pools below the stony surface, which support plant growth. Desert plants have special adaptations such as a dense, compact form and thick, waxy coats. This helps protect them from both heat and animals. Stone pavement is more common in a desert than dunes.
Beetles capture fog-water by basking upside down or forming trenches at the bottom of dunes. They also survive beneath the leaves of Welwitschia plants where temperatures may be 30°C cooler than the surround bare ground.
The Welwitschia plant grows in this barren land by absorb- ing fog-water through its elongated leaves. It is a relic of millions of years ago and is found only in the Namib.
SECTION 3 Climate 531
(cw from top) (1)Cartesia/Getty Images, (2,3)Bernhard Edmaier/Photo Researchers, (4)Michele Westmorland/CORBIS, (5)Wendy Dennis/Visuals Unlimited, (6)Anthony Bannister/CORBIS Ocean and Land Influence Oceans and ocean currents modify the basic climate. Areas with little direct ocean influ- ence are called continental climates and have steep tempera- ture gradients. A climate with strong ocean influence is called a maritime climate. Maritime climates are milder—summers are cooler, winters are warmer, and daily temperatures vary less. The continental climate of Peoria, Illinois, and the mar- itime climate of San Francisco, California, illustrate the con- trast. Although both are near 40° N latitude, the temperature difference between the warmest and coldest months is about 8° C in San Francisco and 30° C in Peoria. Maritime effects are strong enough to keep winters at arctic Spitsbergen, Norway at 78° N latitude, warmer than in International Falls, Minnesota at 48° N latitude.
Precipitation Wind and pressure patterns determine precipi- tation. Humid climates are associated with low-pressure areas in the tropics and the middle latitudes. Rainfall is greater near the equator because the trade winds of both hemispheres converge there, increasing the rising motion. Arid climates are common where high pressure prevails, and aridity is particularly intense in the subtropics on the eastern sides of the subtropical highs. Superimposed upon this general pattern are differences related to location on a continent, as shown for North America in Figure 14. The west coast lies east of the subtropical high, which Figure 14 Lines drawn on a brings cold water currents and stable air. This creates the dry cli- map that connect points of equal mates of California and the southwest. The east coast lies west of precipitation are called isohyets or the subtropical high, where southerly winds bring warm, unstable isohyetal lines. air from the Gulf of Mexico that increases precipitation. Air Research What does the prefix masses can also influence the amount of precipitation an area iso- mean? receives. When continental polar air masses, which originate in the cold, dry artic regions, move across the Midwestern states in the winter, cold, dry
30 weather results. Centimeters Another factor affecting 100 above 500 precipitation is the prevailing 50 50 200 500 winds. Because westerlies prevail in the middle lati- 200 100 tudes, the maritime influence 100 10 100 is stronger on the west 50 100 30 30 50 coast. This explains why San Francisco has a strongly Tropic of Cancer 100100 30 10 developed maritime climate, 200 50 10 100 but Boston has a continental 0 climate.
532 CHAPTER 17 Weather and Climate Influence of Mountains The Rocky Mountains and the Sierra Figure 15 The lee rain shadow Nevada also influence the climate of the west. They act as barriers of the Sierra Nevada and Rocky in the wind, blocking weather systems and altering patterns of Mountains accounts for much of precipitation. When the wind blows perpendicular to one side of the decreased precipitation shown a mountain range, a lee rain shadow forms on the opposite side, in Figure 14. as shown in Figure 15. The Great Plains lie in the lee shadow of the Rocky Mountains and are relatively dry.
Influence of Water Coasts and lakeshores can affect regional climates in several ways. In winter, lake-effect snow often results in regions around the Great Lakes, like those shown in Figure 16. As cold, continental air from the north passes over warmer lake water, the air mass gains heat and moisture. When the air mass reaches the colder land to the south or east of a lake, heavy precipitation, in the form of snow, occurs. Another example of how coasts affect regional climate is a sea breeze. A sea breeze (or lake breeze) blows from the water toward the land in the afternoon, when the land is warmer than the water. Warm air rises over the land creating low pressure that allows cool, dense air to blow from the sea toward land. The reverse happens at night when the land is cooler than Figure 16 People often experi- the water. A land breeze occurs when cool, dense air over land ence similar weather events near creates high pressure causing the air to blow from the land large bodies of water. Cities east of toward the sea. the Great Lakes experience lake- effect snow. Climate Scale Many small-scale variations are superim- posed upon the large-scale climate patterns. Some are regional Lake or local and others, termed microclimates, are variations within Superior small distances. For example, cities create a condition called the Lake Huron heat island effect. Building and pavement materials heat more Lake rapidly than bare land. Vehicles and industry produce pollution Ontario Lake that retains heat. Air rises over a heat island, pulling in air from Michigan the surrounding countryside. On some clear, calm nights, downtown San Francisco can be as much as 8°C warmer than Lake Erie the surrounding rural areas.
SECTION 3 Climate 533 Cold 180 160 140 120100 80 60 40 20 tundra Arid 80 70 Cold boreal Dry winter evergreen forest 60 Warm desert Arid Warm 50 grassland Semi-arid Wet winter Mediterranean 40 Dry summer forest Wet summer temperate Dry winter woodland 30 Warm subtropical Wet deciduous forest Warm tropical Wet deciduous forest Types of Climates Figure 17 Climate zone influ- Geographer Glenn Trewartha and meteorologist Lyle ences the types of vegetation that Horn designed a system to classify climates, shown in Figure 17. will grow there. It has three major divisions—cold or boreal, arid and semi-arid, Infer What are two major factors and climates with adequate heat and precipitation. The last that characterize climate types? includes temperate, subtropical, and tropical climates. These divisions are closely correlated with vegetation.
Summary Self Check Climate and Weather 1. Explain why a climatic normal does not tell you exactly Climate is the net result of interactions what to expect where you live. • involving all aspects of the biogeophysical 2. Identify the five elements of the biogeophysical system system called Earth. called Earth. What causes climate? 3. Explain the association between climate and latitude. The main causes of climate are the 4. Compare and contrast continental and maritime • distribution of solar radiation and the climates. location of pressure and wind systems. 5. Think Critically Would you expect the daily tempera- Oceans, land masses, mountains, and large ture range to be greater in a maritime climate or a • lakes also affect climate. continental climate? Explain. Climates are classified on the basis of • temperature and moisture availability. Prevailing high pressure or the rain shadow of 6. Calculate Range The coolest average summer tem- • mountains can produce dry climates. perature in the United States is 2°C at Barrow, Alaska, and the warmest is 37°C at Death Valley, California. Types of climate Calculate the range of average summer temperatures Climates can be classified into three major in the United States. • divisions.
534 CHAPTER 17 Weather and Climate More Section Review gpescience.com Earth’s Changing Climates
Reading Guide
Review Vocabulary ■ Explain how climate changes Changing climates affect all life trace: a minute, barely detectable seasonally. on Earth. amount present ■ Explain causes of climate change. ■ Describe how we influence climate. New Vocabulary ■ Explain El Niño’s effect on weather. • global warming • El Niño • La Niña
Seasonal Changes Figure 18 The last glacial max- imum was 18,000 years ago when Seasonal changes occur as Earth completes a revolution Earth’s temperature was 6°C cooler around the Sun. The hemisphere tilted toward the Sun experi- than present. ences summer while the hemisphere tilted away from the Sun experiences winter. During the summer, a hemisphere receives &,% +% (% &)% more intense solar radiation and temperatures rise. During &%%
Temperature change (C) –5 the Vikings to sail to Greenland and establish colonies. 18 16 14 12 10 86420 A few centuries later, a cooler period called the Little Ice Thousands of years Age occurred, as shown in Figure 18B. SECTION 4 Earth’s Changing Climates 535 Causes of Climate Change Numerous factors influence climate and act on diverse time scales. Over millions of years, factors such as mountain building and continental movement Dinosaur Extinction are important. Over years and decades, ocean currents, temper- The impact of a large atures, and snow and ice cover play a big role. Climate is the net asteroid 65 million years result of all factors on all timescales. ago on Mexico’s Yucatán Variations in the receipt of solar radiation are important on peninsula may have caused the extinction a scale of hundreds to thousands of years. Changes related to of dinosaurs and other Earth’s orbit are the most important factors, producing changes species. The dust from that determine the rhythmic cycles of glaciation. These include such an impact would changes in the tilt of Earth’s axis of rotation, the shape of its have caused months of orbit, and the timing of the seasons with respect to distance darkness and drastically from the Sun. The tilt, for example, is now 23.5°, but has varied lowered temperatures. between 21.5° and 24.5°. These changes alter the amount and Animals like dinosaurs that needed large sup- distribution of solar radiation that reaches Earth. plies of food would have Sunspots similarly affect the amount of radiation received by suffered most. Research Earth. During one period from 1645 to 1715 sunspot activity what evidence scientists was very low. This period is correlated with long winters and have for such an impact extreme cold temperatures in Western Europe, known as the and report your findings Little Ice Age. Sunspots are important on historical time scales. to your class. Volcanoes also play a role on this scale. They spew out vast amounts of dust that can block sunlight for years. For example, the eruption of Mt. Tambora in Indonesia in 1815 created the cold weather conditions that gave 1816 the name “The Year Without a Summer.” The Human Factor Human activities, such as the burning of fossil fuels, manufac- turing processes, deforestation, draining of wetlands, and intensive agriculture, have influenced Earth’s atmosphere significantly. These activities modify the surface heating and the water and carbon cycles. They also increase the atmospheric concentrations of trace gases, dust and air pollution.
Fossil Fuel Burning Carbon in Deforestation Atmosphere Figure 19 When organisms die Carbon in Organisms and decay, some carbon is stored as humus in the soil and some is released back to the atmosphere as Carbon in Carbon in Soil carbon dioxide. Organisms Describe how trees affect levels of Carbon in Carbon in Rock carbon dioxide and oxygen in the Oceans atmosphere.
536 CHAPTER 17 Weather and Climate The Carbon Cycle The carbon cycle, as shown in Figure 19, follows the exchange of carbon among the ocean, land, and atmosphere. Carbon is the basis of all organic matter. The changes in the carbon cycle are particularly important both meteorologi- cally and ecologically. The carbon cycle is affected in two ways by deforestation and loss of vegetation—less carbon dioxide is absorbed from the atmosphere during photosynthesis, and decay- ing and burning wood adds carbon dioxide to the atmosphere.
Calculate
CARBON DIOXIDE (CO2) CONCENTRATION Concentration of CO2 in the atmosphere has increased at a constant rate of about 4.2 percent per decade over at least the last 30 years. Assuming this rate remains constant, you can predict its concentration in the future by using the following formula: ϩ ϭ ϩ ϫ CO2 (year 10) CO2 (year) CO2 (year) rate of CO2 increase IDENTIFY known values and unknown values Identify the known values: Mauna Loa, Hawaii The concentration of CO2 in 2000 was 369 ppm 380 370 Rate of CO2 increase between 1990 360 and 2000 was 4.2 percent 350 Identify the unknown value: 340 What will be the concentration of 330 oncentration (ppmv) oncentration carbon dioxide in 2010? C 320 2 310 Concentration of CO ϭ ? ppm CO 1955 1965 1975 1985 1995 2005 2 Year SOLVE the problem Substitute the known values into the equation: Concentration in 2010 ϭ 369 ppm ϩ 369 ϫ 0.042 Concentration in 2010 ϭ 384.5 CHECK your answer Multiply 369 ϫ .042 and subtract from 384.5 to get the value in 2000.
1. Use the same method to find carbon dioxide concentration in 2020. 2. Assuming that conservation efforts reduce the rate of carbon dioxide increase to 2.6 percent per decade, predict the concentration in 2010? For more practice problems, go to page 879 and visit Math Practice at gpescience.com .
SECTION 4 Earth’s Changing Climates 537 Trace Gases Today’s atmosphere contains on average about 380 ppm of carbon dioxide. This is an increase of 66 ppm, or 21 percent, since measurements began in 1957. This level is far greater still than at the beginning of the nineteenth century, when levels were stable at 280 ppm. Human activities have also increased the concentration of other trace gases—methane by more than 100 percent, nitrous oxide by about 10 percent. All of these gases are important in heating the atmosphere.
Global Warming Global warming is an increase in the aver- Figure 20 The concentration of age global temperature of Earth. Global temperatures have ozone over Antarctic has dramati- increased over the last century by about 1°C. This may seem cally decreased between 1979 and small, but the entire global temperature increase since the last 2003. Concentrations in the hole ice age is only 6°C. Our understanding of global warming is are about eighty percent lower than incomplete, but evidence strongly suggests that the increase in what would be there naturally. trace gases is an important component. Explain why scientists are con- cerned about decreasing concentra- The Ozone Hole As early as the 1970s, scientists were con- tion of ozone in the stratosphere. cerned that synthetic chemical compounds could destroy atmospheric ozone. They worried about exhaust from super- sonic aircraft and chlorine and fluorine compounds, such as the CFCs (chlorofluorocarbons) used in refrigeration, aerosol sprays, and other processes. Since ultraviolet radiation breaks down DNA, less protection from solar ultraviolet radiation potentially could affect the quality of life on Earth. In 1985, British scientists found a hole in the ozone layer over Antarctica. The change in the ozone layer between 1979 and 2003 is shown in Figure 20. When study of the air in this hole showed that it was largely man-made, an international agreement was Oct. 1979 made to limit the use of CFCs. Recent studies indicate that actions taken as a result of the agreement are having an effect on levels of chlorine in the atmosphere, which are decreasing each year.
The Land Surface Humans change the land surface by draining swamps, plowing fields, and building cities. Extensive studies have suggested that these processes might affect local or regional climate, but the issue is still controversial. The climate of cities is different than the climate of the surrounding coun- tryside. Effects on larger scales are not as clear. One concern is desertification. Desertification is the end Oct. 2003 product of many types of changes that make once-productive land unusable. Human activities such as overgrazing Total Ozone (Dobson Units) of livestock, deforestation, and irrigation of crops may contribute to the process of desertification in some areas of the world. 150 325 500
538 CHAPTER 17 Weather and Climate El Niño and La Niña El Niño is a climatic event that involves the atmosphere and oceans. Normally, the trade winds blow warm surface water westward toward a low pressure area in the western Pacific. The warm surface water is replaced by cold, nutrient-rich water that is upwelled from below the surface. When the tradewinds weaken, surface pressure patterns break down and the flow of warm water is reversed. Nutrient-rich cold water is no longer upwelled and warm, nutrient-poor water remains at the surface. Fewer fish and other marine life can be supported by the nutrient-poor water. Rainfall in the western Pacific decreases, where as heavy rain and flooding can occur on the normally dry coast of Peru. El Niño can dramatically alter global weather pat- terns. For example, a strong El Niño can lead to flooding and mudslides in California, as shown in Figure 21, and droughts in India, Australia, and parts of Africa. The opposite of El Niño is La Niña, which occurs when tradewinds in the Pacific are unusually strong and equatorial Figure 21 Parts of the Pacific oceanic surface temperatures are colder than normal. La Niña Coast Highway in California have can cause drought in the southern United States and excess rain- been disrupted by erosion and fall in the northwest. mudslides caused by El Niño.
Summary Self Check Seasonal Changes 1. Identify ways that humans may be affecting climate. The tilt of Earth’s axis changes the amount of 2. Explain why the contrast between land and water • solar radiation received by the northern and changes with the seasons. southern hemispheres throughout the year, 3. Explain why it is difficult to identify any single cause of causing the seasons. an observed climate change. Long-term Climate Changes 4. Think Critically What can be done to stop global Cycles of glaciation occur on the scale of tens warming? What can you do to help? • of thousands of years. Sunspots and volcanoes influence climate on • shorter timescales. 5. Use Percentages The eruption of Mount Pinatubo in 1991 put large amounts of dust into the atmosphere. The Human Factor Scientists say this decreased the average global tem- Human activities have increased the perature about 0.8 percent during the next year. How • concentration of trace gases and decreased would this affect an area with an average temperature stratospheric ozone. of 25°C before the eruption? El Niño and La Niña 6. Calculate Areas of the southeastern United States may receive 15 percent of their rain during hurricanes. If El Niño is a warming of the Pacific Ocean with average rainfall for this area ranges from 100–200 cm, • worldwide effects. La Niña is the opposite of how much of this might be from hurricanes? El Niño.
More Section Review gpescience.com SECTION 4 Earth’s Changing Climates 539 APF/Getty Images DesignDesign YourYour OwnOwn
Investigating Microclimate
Goals Real World Problem ■ Investigate how envi- While we can talk about global climate or regional climate, we also ronmental variables can discuss climate on the scale of a few meters. We call climate at respond to various this scale a microclimate. For example, because cold, heavy air drains microclimates. downhill, valley fog sometimes forms in moist, low-lying areas. Along the California coast, coastal fog collects on the needles of Possible Materials redwood trees, drips to the ground, and is absorbed by the tree’s directional compass shallow root system. This microclimate helps the coastal redwoods thermometer survive, nestled in the fog belt along the California coast. In this lab, rain gauge you will investigate local differences in microclimate. meter stick small plastic cups *graduated cylinder Form a Hypothesis *Alternate materials Choose an aspect of climate, such as precipitation, light, or tempera- ture. Form a hypothesis to explain how this aspect influences local Safety Precautions environments. Predict how these factors will vary in response to dif- ferences in your microclimate variable.
540 CHAPTER 17 Weather and Climate Bill Ross/CORBIS Test Your Hypothesis Make a Plan 1. Decide what microclimate factor you will investigate, and what envi- ronmental factor you will monitor for effects. 2. How will you measure the selected microclimate variable? What equipment will you need? How often will you make measurements? 3. Choose sites for making measurements. Will these sites vary in micro- climate? Is the environmental variable you chose present in these places? 4. Decide how you will measure your environmental variable. What equipment will you need? How often will you make measurements? Should the microcli- mate measurement happen at the same time? 5. Prepare a data table to record your measurements. Will you record the time of the measurements? Should you record the weather at the time of measurements? 6. Before you begin, list the steps of your procedure. Include all materials needed for each step. Does your procedure give you the data necessary to test your hypothesis? Follow Your Plan 1. Be sure that your teacher approves your plan before you start. 2. Carry out your experiment as planned. Be sure to record all data in the appropri- ate places. Follow all appropriate safety precautions. 3. Record all observations and data in your Science Journal.
Analyze Your Data 1. Make a graph of your data. Put the microclimate variable on the y-axis, and the environmental variable on the x-axis. 2. Discuss any trends you see in the data based on your graph. 3. Infer any effects that the weather had on microclimate variables. How did this affect your environmental variable?
Conclude and Apply 1. Discuss your predicted environmental response to microclimate. Did your results support your Compare your results with the data of hypothesis? other students who measured the same 2. Predict how changes in global climate would microclimate variable. Present the affect the microclimate and response variables combined data to the class. For more help, that you studied. refer to the Science Skills Handbook.
LAB 541 Philippe Colombi/Getty Images The Grapes of Wrath by John Steinbeck
Understanding In The Grapes of Wrath, Steinbeck tells Literature the story of the fictional Historical Novels Authors often use his- torical events as inspiration. When a piece Joad family, who lived in of fiction combines historical events or Oklahoma in the 1930s. characters with fictional plot and dialogue, Like thousands of families it becomes a historical novel.Well-written- living in the drought- historical fiction can aid the reader in stricken dust bowl of the understanding how people actually experi- central United States, the enced an important time in history. Joads were tenant farmers who lost their farm. Such families piled their belongings into rickety trucks and migrated to California seeking work as fruit pickers. Although the drought alone caused much Respond to the Reading hardship, it was gigantic dust storms that finally 1. How does the dust storm affect the destroyed their crops. Steinbeck describes such a crops? storm in the following words: 2. What might cause such a dust storm? “The wind grew stronger, whisked under 3. Linking Science and Reading Write a stones, carried up straws and old leaves, and even paragraph describing the effects of a little clods, marking its course as it sailed across hurricane or tornado. the fields. The air and the sky darkened and through them the sun shone redly, and there was a raw sting in the air. During a night the wind raced faster over the land, dug cunningly among The dust bowl the rootlets of the corn, and the corn fought the resulted from inter- wind with its weakened leaves until the roots were actions between natural elements, such as freed by the prying wind and then each stalk set- climate,plants,and soil,and human elements, such as farming practices and economics. tled wearily sideways toward the earth and When the dust bowl occurred,vegetation was pointed the direction of the wind.” already sparse. This reduced friction and When the storm finally ended, the buildings, allowed the wind to gain speed.With no mois- fences, and trees were blanketed with thick layers of ture to bind soil particles together, the soil dust—a grim reminder of how the Joads’ lives had eroded.Dust from these storms was carried up been changed forever. to 3,000 km away from its original source.The dust storms were a type of squall that some- times bring rain to these semi-arid plains.
542 CHAPTER 17 Weather and Climate AP/Wide World Photos Earth’s Atmosphere Climate 1. Earth’s atmosphere is 78 percent nitrogen, 1. Climate refers to the mean weather condi- 21 percent oxygen, one percent argon, and tions and their annual variations in an area. includes small amounts of trace gases. 2. Climate is part of an Earth system that 2. The stratosphere is the upper layer of the includes the atmosphere, biosphere, atmosphere where temperature always hydrosphere, cryosphere, and lithosphere. increases with height. The troposphere is 3. Latitude is the most important factor in the lower layer where most weather determining climate. occurs. 4. Continents, mountains, and oceans influ- 3. The troposphere is heated primarily by ence climate on a large scale, and small- Earth’s surface after it absorbs radiation scale variations are termed microclimates. from the Sun. 4. Land absorbs and emits heat efficiently, but Earth’s Changing Climates water resists temperature change. 1. 5. Clouds form when warm air carrying Long-term changes include cycles of water vapor rises until it is cool enough glaciation. Causes of climate change include to condense. changes in Earth’s orbit, solar activity, volcan- ism, and human intervention. Weather 2. Global warming has been documented. The reasons for it are complex and not fully 1. Major pressure belts H understood. L L and wind belts are H HH 3. Increased concentrations caused by unequal of trace gases and dam- heating between the L LL age to the ozone layer are equator and the poles H HH probably caused by and modifications human activities. resulting from Earth’s L L H rotation. 4. El Niño and La Niña affect ocean currents and 2. Specific weather patterns are associated coastal winds, causing with high and low pressure cells. serious droughts and 3. Air masses are large blocks of air with simi- flooding in some areas. lar properties of moisture and temperature throughout. They interact in zones called weather fronts. Use the Foldable that you made at the begin- 4. Severe weather includes thunderstorms, ning of this chapter to review what you have learned about downbursts, tornadoes, and hurricanes. weather and climate.
Interactive Tutor gpescience.com CHAPTER STUDY GUIDE 543 12. Which is the percent of solar radiation reflected from the surface? biosphere p. 529 maritime climate p. 532 A) albedo continental climate p. 532 sea breeze p. 533 B) Coriolis effect El Niño p. 539 subtropical high p. 525 C) greenhouse effect global warming p. 538 temperature inversion greenhouse effect p. 520 p. 519 D) urban heat island jet stream p. 525 troposphere p. 519 13. Which is the most important factor in La Niña p. 539 weather front p. 526 latent heat p. 520 westerlies p. 524 determining climate at a given location? lee rain shadow p. 533 A) altitude C) latitude B) continents D) mountains Match the correct vocabulary word(s) with each Use the illustration below to answer question 14. definition given below. 1. area of interaction between air masses Leeward side 2. climate with a strong ocean influence Windward side 3. energy used to evaporate water 4. layer of the atmosphere where most weather occurs 14. 5. global weather event(s) that involve Which influence on regional climate is oceans and the atmosphere shown above? A) continental location 6. most important of three major wind belts B) lake effect 7. fast, powerful air current that affects many C) lee rain shadow weather processes D) maritime location 8. area of reduced precipitation on one side 15. Which triggers droplet formation in clouds? of a mountain range A) evaporation C) ozone 9. a region of very stable air that resists rising B) dust D) thermals needed to form clouds and dispel pollution 16. What type of weather is most closely 10. warming of the atmosphere involving heat associated with a warm front? absorption by trace gases A) drizzle or steady rain B) downbursts or windshear C) hurricanes or tornadoes D) thunderstorms Choose the word or phrase that best answers the question. 17. Which is a trace gas? 11. Which has great ranges in temperature A) argon C) oxygen and little ocean influence? B) nitrogen D) ozone A) continental climate 18. Which surface reflects solar radiation B) El Niño the most? C) La Niña A) bare soil C) snow fields D) maritime climate B) forest D) ocean
544 CHAPTER REVIEW Vocabulary PuzzleMaker gpescience.com Use the illustration below to answer question 26. Interpreting Graphics Day Night 19. Illustrate Earth’s major pressure belts and wind belts, with labels showing the Sea breeze Land breeze westerlies and the trade winds. 20. Make a table comparing characteristics of Cold Warm Warm Cold continental and maritime climates. Use the data in the following table to answer question 21. 26. Explain why a sea breeze blows toward the land in the afternoon, and a land breeze City Temperatures blows toward the water in the evening. Cities at Average July Average January 27. Infer how global warming might increase Degrees N Temperature Temperature the frequency of severe weather, such as Latitude (°C) (°C) hurricanes. 72 20 Ϫ45 28. Describe the carbon cycle and explain how 41 21 9 human activities might interfere with it. 45 29 Ϫ2 29. Explain how water droplets form in clouds Ϫ 40 31 10 and the conditions needed to make them fall as some form of precipitation. 21. Identify Based on the data in the table above, 30. Identify some of the ways that human activi- identify the latitudes of the cities that ties have interfered with the water cycle and have maritime and continental climates. describe some results of these activities. 31. Explain how El Niño affects global weather patterns.
22. Explain why the continental United States is prone to severe weather, such as tornadoes 32. Convert Units The high temperature of a and hurricanes. summer day in the United States might 23. Infer why scientists are so concerned about be 81°F. What would this temperature finding a hole in the ozone layer over be in France where they use Celsius Antarctica. temperatures? Hint: Use the formula °C ϭ (°F Ϫ 32) ϫ 5/9. 24. Form a hypothesis about how we might deter- 33. Compare Ratios City A had 175 cloudy mine whether human activities have days in 2004. In 2004, 56 percent played a role in global warming. of city B’s days were cloudy. Which 25. Identify some ways that plants and animals city had more cloudy days? Show the might adapt to changing climate patterns. calculations you did to find your Hint: Think of how organisms adapt to answer. extreme conditions.
More Chapter Review gpescience.com CHAPTER REVIEW 545 Record your answers on the answer sheet provided by your teacher or on a sheet of paper.
4. Which type of air mass would most likely be moist and warm? A. continental polar 1. Which makes up most of Earth’s atmosphere? B. continental tropical A. carbon dioxide C. maritime polar B. carbon monoxide D. maritime tropical C. nitrogen D. oxygen 5. Which is a series of windy gusts formed when a downdraft hits Earth’s surface with Use the figure below to answer question 2. particularly strong force? Comparison of CO2 Concentration to Time of Year and Latitude A. hail
360 B. squall 350 340 90N C. thunderstorm
(ppm) 330 0 Concentration 1982
2 1983 D. tornado 1984 -90S
CO Latitude Use the diagram below to answer question 6. 2. Which is used by photosynthetic organisms
to produce almost all of Earth’s atmos- Sun pheric oxygen? A. carbon monoxide B. carbon dioxide C. methane D. nitrogen
3. Which accumulated in the stratosphere over millions of years and shielded Earth from ultraviolet rays from the Sun? A. argon 6. Which is caused by absorption of long wavelength radiation by trace gases? B. nitrogen A. condensation C. oxygen B. greenhouse effect D. ozone C. latent heat D. precipitation
546 STANDARDIZED TEST PRACTICE Use the table below to answer question 7.
Land Surface Albedo Bare soil 25 Snow 90 10. Describe the major differences between the conditions that existed 18,000 years Desert 50 ago from the conditions of the present. Dense forest 10 Include descriptions of the climatic, geo- logical, and biological conditions. 7. Over which surface is the least amount of solar radiation absorbed? 11. Explain how the stratospheric ozone layer A. bare soil is formed. Also explain its importance in B. dense forest regard to the quality of life on Earth. C. desert 12. What causes uneven patterns of heating D. snow on Earth’s surface?
8. Which are fast, powerful flows of wind 13. Which factors cause climate? imbedded in global wind systems? A. jet streams B. sea breezes C. subtropical highs D. westerlies Use diagram below to answer question 14.
Warm air
9. If the average concentration of carbon diox- ide in Earth’s atmosphere at the beginning Cold air of the nineteenth century was 280 ppm and it presently is 380 ppm, what percentage of today’s concentration existed at the begin- ning of the nineteenth century? 14. PART A What are weather fronts? PART B How do air masses interact at a cold front? Review Never leave any answer blank.
Standardized Test Practice gpescience.com STANDARDIZED TEST PRACTICE 547