2. Unit 6/7: The Atmosphere and the Oceans Chapter 11 Atmosphere

3. NC Earth Science Essential Standards EEn. 2.5 - Understand the structure of and processes within our atmosphere. EEn. 2.5.1 - Summarize the structure and composition of our atmosphere. EEn. 2.5.2 - Explain the formation of typical air masses and the weather systems that result from air mass interactions. EEn. 2.5.3 - Explain how cyclonic storms form based on interaction of air masses. EEn. 2.5.4 - Predict the weather using available weather maps and data (including surface, upper, atmospheric winds and satellite imagery). EEn. 2.5.5 - Explain how human activities affect air quality. NC ESES Unit 6: The Atmosphere and the Oceans

4. NC Earth Science Essential Standards EEn. 2.6 - Analyze patterns of global climate change overtime. EEn. 2.6.1 – Differentiate between weather and climate. EEn. 2.6.2 - Explain changes in global climate due to natural processes. EEn. 2.6.3 – Analyze the impacts that human activities have on global climate changes (such as burning hydrocarbons, greenhouse effect, and deforestation). EEn. 2.6.4 – Attribute changes to Earth’s systems to global climate change (temperature change, changes in pH of ocean, sea levels changes, etc.). NC ESES Unit 7: The Atmosphere and the Oceans

5. Objective: -Describe the composition of the atmosphere. -Compare and contrast the various layers of the atmosphere. - Identify three methods of transferring energy throughout the atmosphere. -Describe the various properties of the atmosphere and how they interact. -Explain why atmospheric properties change with changes in altitude. -Explain how clouds are formed -Identify the basic characteristics of different cloud groups. -Describe the water cycle. Reading Assignment: Read Chapter 11; pages: 270-291 Ozone Troposphere Stratosphere Mesosphere Thermosphere Exosphere Radiation Conduction Convection Temperature Heat Dew point Condensation Lifted Condensa- tion level Temperature -inversion Humidity Relative -humidity Condensation -nuclei Orographic -lifting Stability Latent heat Coalescence Precipitation Water cycle evaporation NC ESES Unit 6/7: The Atmosphere and the Oceans Vocabulary:

6. Unit 6/7: The Atmosphere and the Oceans 11.1 Atmospheric Basics

7. Objectives Describe the composition of the atmosphere. Atmospheric Basics Compare and contrast the various layers of the atmosphere. Identify three methods of transferring energy throughout the atmosphere. –ozone –troposphere –stratosphere –mesosphere –thermosphere Vocabulary –exosphere –radiation –conduction –convection

8. About 99 percent of the atmosphere is composed of nitrogen and oxygen, with the remaining one percent consisting of small amounts of argon, hydrogen, carbon dioxide, water vapor, and other gases. Atmospheric Composition Air is a combination of many gases, each with its own unique characteristics. Atmospheric Basics

9. Atmospheric Composition Atmospheric Basics

10. Atmospheric Composition Key Atmospheric Gases Atmospheric Basics –The amount of water vapor in the atmosphere can be as much as four percent of the atmosphere or as little as almost zero. –Carbon dioxide, another variable gas, makes up under one percent of the atmosphere. –The levels of both carbon dioxide and water vapor play an important role in regulating the amount of energy the atmosphere absorbs. –Water vapor, gaseous form of water, is the only substance in the atmosphere that exists in three states: solid, liquid, and gas.

11. Atmospheric Composition Key Atmospheric Gases Atmospheric Basics –The three states of water in the atmosphere is very important, because when water changes from one state to another, heat is either absorbed or released which greatly affects the creation of weather and climate. –The atmosphere also contains solids in the form of tiny particles of dust, salt, and ice. –Dust carried by wind –Salt picked up by ocean spray –Ice in the form of hail and snow

12. Atmospheric Composition Ozone (Another component of the atmosphere) Atmospheric Basics –Ozone (O 3 ), is a gas formed by the addition of a third oxygen atom to an oxygen molecule (O 2 ). –Evidence indicates that the ozone layer is thinning. –Ozone is important because it absorbs ultraviolet radiation before reaching the surface of Earth. –If ozone did not control the amount of ultraviolet radiation reaching the Earth’s surface, our fragile skin could not tolerate exposure to the Sun for long.

13. Each layer differs in composition and temperature –Troposphere –Stratosphere –Mesosphere –Thermosphere –Exosphere Structure of the Atmosphere The atmosphere is made up of several different layers. Atmospheric Basics “Tom Stole Matt’s Tuttle Egg”

14. Structure of the Atmosphere Atmospheric Basics The five main layers of the atmosphere vary in temperature and chemical composition.

15. Atmospheric Composition Lower Atmospheric Layers Atmospheric Basics –Troposphere, the layer closest to Earth’s surface, contains most of the mass of the atmosphere, including water vapor. –Most weather takes place in and most air pollution collects in the troposphere. –The troposphere is characterized by a general decrease in temperature from bottom to top. –The upper limit of the troposphere, called the tropopause, varies in height (16km@tropics / 9km@poles). Temperature Variations with Altitude

16. Atmospheric Composition Lower Atmospheric Layers Atmospheric Basics –The stratosphere, which is above the tropopause, is a layer made up primarily of concentrated ozone –Ozone absorbs more ultraviolet radiation than air does. –The stratosphere is heated because ozone absorbs ultraviolet radiation, and air gradually increases in temperature to the top of the layer, called the stratopause (about 50km high). Temperature Variations with Altitude

17. Atmospheric Composition Upper Atmospheric Layers Atmospheric Basics –The mesosphere is the atmospheric layer above the stratopause. –No concentrated ozone in the mesosphere, so the temperature decreases. –The top boundary of this layer is the mesopause

18. Atmospheric Composition Upper Atmospheric Layers Atmospheric Basics –The thermosphere is the atmospheric layer above the mesopause that contains only a minute portion of the atmosphere’s mass. –The little air in this region increase in temperature to more than 1000°C, however the molecules are so sparse and widely spaced, it would not feel warm to us.

19. Atmospheric Composition Upper Atmospheric Layers Atmospheric Basics –The ionosphere is part of the thermosphere and made up of electrically charged particles and layers of progressively lighter gases. –The exosphere, which is composed of light gases such as helium and hydrogen, is the outermost layer of Earth’s atmosphere. –Above the exosphere lies outer space and there is no clear boundary between the atmosphere and space.

20. This energy is transferred to Earth and throughout the atmosphere in three ways: radiation, conduction, and convection. Solar Fundamentals The Sun is the source of all energy in the atmosphere. Atmospheric Basics

21. Solar Fundamentals Radiation Atmospheric Basics –The Sun is shining on, and therefore warming, some portion of Earth’s surface at all times. –This method of energy transfer is called radiation. –Radiation is the transfer of energy through space by visible light, ultraviolet radiation, and other forms of electromagnetic waves. –While Earth is absorbing solar radiation, it is also continuously sending energy back into space.

22. Solar Fundamentals Radiation Atmospheric Basics About 35% of incoming radiation is reflected by the clouds, Earth’s surface, and the atmosphere. About 15% is absorbed by the atmosphere. About 50% of incoming radiation is absorbed directly or indirectly by Earth’s surface.

23. Solar Fundamentals Radiation Atmospheric Basics Over the course of a year, Earth sends back into space just about as much energy as it receives from the Sun. If Earth sent back too much energy, it would gradually cool off, while if it sent back too little energy, it would warm up to potentially dangerous levels. Different areas absorb energy at different rates; general rule, darker objects absorb energy faster than lighter ones.

24. Solar Fundamentals Radiation Atmospheric Basics –The rate of absorption for any particular area varies depending on the physical characteristics of the area and the amount of solar radiation it receives. –For the most part, solar radiation does not heat air directly. Most of the solar radiation that travels through the atmosphere does so at short wavelengths, which are not easily absorbed. –The surface then radiates energy, but the radiation it gives off has a longer wavelength than the energy coming the Sun. –The energy radiated by Earth’s surface does not pass through the atmosphere and warms the air through the process of conduction and convection.

25. Solar Fundamentals Radiation-Conduction-Convection Atmospheric Basics The Sun’s energy is transferred throughout the atmosphere by the process of conduction, convection, and radiation.

26. Solar Fundamentals Conduction Atmospheric Basics –Conduction is the transfer of energy that occurs when molecules collide. –Through conduction, energy is transferred from the particles of air near Earth’s surface to the particles of air in the lowest layer of the atmosphere. –For conduction to occur, substances must be in contact with one another. –Conduction affects only a very thin atmospheric layer near Earth’s surface. Example: when a pot of water is placed on a heated burner of a stove, energy is transferred from stove’s heated burner to the bottom of the pot into the lowest part of the water.

27. Solar Fundamentals Convection Atmospheric Basics –Convection is the transfer of energy by the flow of a heated substance. –Pockets of air near Earth’s surface are heated, become less dense than the surrounding air, and rise; as the warm air rises, it expands and starts to cool. –When it cools below the temperature of the surround- ing air, it increases in density and sinks. –Convection currents are among the main mechanisms responsible for the vertical motions of air, which in turn cause different types of weather. Example: rising bubbles bring warm water to the top of the pot, water at the top then cools, causing pockets of cool water to sink and be reheated at the bottom of pot.

28. Section Assessment 1.Match the following terms with their definitions. ___ radiation ___ conduction ___ convection Atmospheric Basics A.the transfer of energy that occurs when molecules collide B.the transfer of energy through space by visible light, ultraviolet radiation, and other forms of electromagnetic waves C.the transfer of energy by the flow of a heated substance B A C

29. Section Assessment 2.Label the layers of Earth’s atmosphere. Atmospheric Basics Stratosphere Mesosphere Thermosphere Exosphere Troposphere

30. Section Assessment 3.Why is ozone important? Atmospheric Basics Ozone absorbs ultraviolet radiation from the sun. If ozone did not control the amount of ultraviolet radiation reaching Earth’s surface, our skin could not tolerate exposure to the Sun for very long.

31. Unit 6/7: The Atmosphere and the Oceans 11.2 State of the Atmosphere

32. Objectives Describe the various properties of the atmosphere and how they interact. Explain why atmospheric properties change with changes in altitude. –temperature –heat –dew point –condensation –lifted condensation level –temperature inversion –humidity –relative humidity Vocabulary State of the Atmosphere

33. Temperature Versus Heat Temperature is a measurement of how rapidly or slowly molecules move around. State of the Atmosphere Heat is the transfer of energy that occurs because of a difference in temperature between substances. Heat is the transfer of energy that fuels atmospheric processes, while temperature is used to measure and interpret that energy. Temperature and heat are two different concepts. More molecules or faster moving molecules in a given space generate a higher temperatures.

34. Temperature Versus Heat Measuring Temperature State of the Atmosphere Temperature can be measured in degrees Fahrenheit (°F), in degrees Celsius (°C), or in kelvins (K), the SI unit of temperature. Kelvin scale measures the number of kelvins above absolute zero, a point where molecular motion theoretically stops. Heat flows from an object of higher temperature to an object of lower temperature.

35. Temperature Versus Heat Dew Point State of the Atmosphere –The dew point is the temperature to which air must be cooled at constant pressure to reach saturation. –Saturation is the point at which the air holds as much water vapor as it possibly can. –Condensation cannot occur until air is saturated. –Condensation occurs when matter changes state from a gas to a liquid. –In this case, water vapor changes into liquid water and eventually falls as rain. Given its role in this process, dew point is often called the condensation temperature.

36. Vertical Temperature Changes State of the Atmosphere

37. Vertical Temperature Changes The temperature on a mountain top is cooler than at lower elevations, because the temperature of the lower atmosphere decreases with increasing distance from its heat source –Earth’s surface. State of the Atmosphere An air mass that does not exchange heat with its surroundings will cool off by about 10°C for every 1000 m increase in altitude. This is called dry adiabatic lapse rate – the rate at which unsaturated air, to which no heat is added or removed, will cool.

38. Vertical Temperature Changes If the air is able to continue rising, eventually it will cool to its condensation temperature. State of the Atmosphere The lifted condensation level, or LCL, is the height at which condensation occurs. The moist adiabatic lapse rate is the rate at which saturated air cools and ranges from about 4°C/1000 m in very warm air to almost 9°C/1000m in very cold air. Clouds form when water vapor condenses into water droplets, so the height of the LCL often corresponds to the base of clouds. Above the LCL, air becomes saturated and cools more slowly.

39. Vertical Temperature Changes State of the Atmosphere Condensation occurs at the lifted condensation level (LCL); air above the LCL is saturated and thus cools more slowly than air below the LCL.

40. Air Pressure and Density The gravitational attraction between Earth and atmospheric gases causes particles of gas to be pulled toward the center of Earth. State of the Atmosphere Air pressure increases as you near the bottom of the atmosphere because of the greater mass of the atmosphere above you. Atmospheric pressure decreases with height because there are fewer and fewer gas particles exerting pressure. The density of air is proportional to the number of particles of air occupying a particular space.

41. Air Pressure and Density State of the Atmosphere The table shows, the density of air increases as you get closer to the bottom of the atmosphere. This is because gases at the top of the atmosphere press down on the air below, thereby compressing the particles and increasing the density of the air. So on a mountain, the temp., pressure, and density, are all less than they are at lower elevations.

42. Pressure-Temperature-Density Relationship Temperature, pressure, and density are related. State of the Atmosphere In the atmosphere, temperature is directly proportional to pressure. If an air mass maintains a certain density-that is, the number of gas particles in a fixed volume remains the same; as temperature increases or decreases, pressure does, too.

43. Pressure-Temperature-Density Relationship The relationship between temperature and density is inversely proportional. State of the Atmosphere If an air mass maintains a certain pressure, as temperature increases, density decreases, and as temperature decreases, density increases. This is why air rises when its temperature increases – it becomes less dense.

44. Pressure-Temperature-Density Relationship In most atmospheric interactions, however, neither density nor pressure remains unchanged. State of the Atmosphere Temperature varies with changes in both pressure and density. Temperature is proportional to the ratio of pressure to density, which decreases with increasing altitude. = D = P

45. Pressure-Temperature-Density Relationship Temperature Inversion State of the Atmosphere –A temperature inversion is an increase in temperature with height in an atmospheric layer. –This can happen when the lower layers of the atmosphere lose heat to Earth’s surface and become cooler than the air above them. –A temperature inversion can act like a lid to trap pollution under the inversion layer. –In all cases, the presence or absence of inversions can have a profound effect on weather conditions. −It’s called a temperature inversion because the temperature-altitude relationship is turned upside down.

46. Wind If you have ever entered a large, air-conditioned building on a hot summer day, you may have noticed a sudden rush of the cold air greeted you when you opened the door. State of the Atmosphere This happened because the air conditioner created an imbalance between the warm, less dense air outside, to the cool, more-dense air inside. The cool air, being denser, had settled toward the bottom of the building, when the door opened, the cool, dense air rushed out to equalize the imbalance. The rush of air that you felt is known as wind.

47. Wind The atmosphere is much like an air-conditioned building. Cool air, being more dense, sinks and forces warm, less-dense air upward. State of the Atmosphere These imbalances, in turn, create areas of high and low pressure. Wind can be thought of as air moving from an area of high pressure to an area of low pressure. Wind speed generally increases with height in the atmosphere because there is less friction. In the lower atmosphere, air generally moves from areas of high-density to areas of low density.

48. Relative Humidity Air in the lower portion of the atmosphere always contains at least some water vapor. State of the Atmosphere Humidity is the amount of water vapor in air. Relative humidity is the ratio of water vapor in a volume of air compared to how much water vapor that volume of air is capable of holding. Relative humidity varies with temperature; warm air is capable of holding more moisture than cool air. If the temperature of a room increased, the air in the room would be capable of holding more moisture, and if no additional water vapor was added to the air, its relative humidity would decrease.

49. Relative Humidity Relative humidity is expressed as a percentage. If a certain volume of air is holding as much water vapor as it possibly can, then its relative humidity (RH) is 100%. State of the Atmosphere –If that same volume of air is holding half as much water vapor as it can, then it has a RH of 50%.

50. Section Assessment 1.Match the following terms with their definitions. ___ temperature ___heat ___ dew point ___ humidity State of the Atmosphere A.a measurement of how rapidly or slowly molecules move around B.the temperature to which air must be cooled at constant pressure to reach saturation C.the amount of water vapor in air D.the transfer of energy that occurs because of a difference in temperature between substances A D B C

51. Section Assessment 2.What is the significance of 0 kelvin? State of the Atmosphere Nothing can be colder than 0 K. This is called absolute zero and is the point where molecular motion theoretically stops.

52. Section Assessment 3.Identify whether the following statements are true or false. State of the Atmosphere ______ 1 m 3 of air containing 5 g of water vapor has a higher relative humidity at 10ºC verses 20ºC. ______ As air flows down from a mountain, and its pressure increases, its temperature will fall. ______Beyond the liquid condensation level, temperature generally increases. ______ Condensation cannot occur until air temperature reaches its dew point. true false true

53. Unit 6/7: The Atmosphere and the Oceans 11.3 Moisture in the Atmosphere

54. –condensation nuclei –orographic lifting –stability –latent heat Objectives Explain how clouds are formed. Identify the basic characteristics of different cloud groups. Describe the water cycle. Vocabulary Moisture in the Atmosphere –coalescence –precipitation –water cycle –evaporation

55. Cloud Formation Buoyancy is the tendency for air to rise or sink as a result of differences in density. Moisture in the Atmosphere Clouds form when warm, moist air rises, expands, and cools in a convection current. Condensation nuclei are small particles in the atmosphere around which cloud droplets can form. They come from a variety of sources, including sea salt and dust.

56. Cloud Formation Orographic lifting occurs when wind encounters a mountain and the air has no place to go but up. Moisture in the Atmosphere The air expands and cools resulting in cloud formation. Another method of cloud formation involves the collision of air masses of different temperatures.

57. Cloud Formation Recall that cold, more-dense air is heavier than warm, less-dense air, so it collects near Earth’s surface. Moisture in the Atmosphere As warmer air collides with cooler air, the bulk of it will be forced to rise over the more-dense, cold air. As the warm air cools, the water vapor in it condenses and forms a cloud.

58. Cloud Formation Stability Moisture in the Atmosphere –Regardless of how a cloud forms, all rising air expands and cools. How rapidly any given mass of air cools determines its stability. –Stability is the ability of an air mass to resist rising. –The rate at which an air mass cools depends in part on the temperature of the surface beneath the air. –The temperature of the surrounding air masses and the temperature of the air mass itself also play a role in determining the cooling rate.

59. Cloud Formation Instability Moisture in the Atmosphere –Air can become unstable if it is cooler than the surface beneath it. In this case, heat flows from the warmer surface to the cooler air. The air warms and becomes less dense than the surrounding air. The less dense air mass rises. –If temperature conditions are right and the air mass rises rapidly, it can produce the type of clouds associated with thunderstorms.

60. Cloud Formation Latent Heat Moisture in the Atmosphere –As water vapor in the air condenses, heat is released. –The energy to change liquid water into a gaseous state is stored in the water vapor. –Latent heat is stored energy in water vapor that is not released to warm the atmosphere until condensation takes place. –The amount of water vapor present in the atmosphere is a significant source of energy because of the latent heat it contains. –When condensation occurs, this latent heat can provide energy to a weather system, thereby increasing its intensity.

61. Types of Clouds When a mass of rising air reaches its LCL, water vapor condenses into droplets of liquid water or ice depending on the temperature. Moisture in the Atmosphere If the density of these droplets is great enough, they become visible in the form of a cloud. This process can take place at many different altitudes, to include the surface of Earth in the form of fog; cloud can form different shapes depending on the factors involved in their formation.

62. Types of Clouds Clouds are generally classified according to a system originally developed by English naturalist Luke Howard in 1803. Moisture in the Atmosphere The modern system groups clouds by the altitude at which they form and by their shape. –Low clouds typically form below 2000 m. –Middle clouds form between 2000 m to 6000 m. –High clouds composed of ice crystals form above 6000 m. –Vertical development clouds spread throughout all altitudes at the same time.

63. Types of Clouds Moisture in the Atmosphere

64.  Clouds are classified on the basis of their form and height. Cirrus (cirrus = curl of hair) are clouds that are high, white, and thin. Cumulus (cumulus = a piled) are clouds that consist of rounded individual cloud masses. Stratus (stratus = sheet or layered) are clouds best described as sheets or layers that cover much or all of the sky. Clouds Moisture in the Atmosphere Nimbus (nimbus = a rain) low, dark, gray rain clouds that can cause heavy precipitation.

65. Types of Clouds Moisture in the Atmosphere

66. Types of Clouds Low Clouds Moisture in the Atmosphere –If rising air stays warmer than the surrounding air, the cloud will continue to grow. –If the air does not stay warmer than the surrounding air, the cloud will flatten out and winds will spread it horizontally into a stratocumulus or layered cumulus clouds. –Stratus, a layered cloud that covers much or all of the sky, often forms when fog lifts away from Earth’s surface. –Nimbostratus clouds are the main precipitation makers.

67. Types of Clouds Moisture in the Atmosphere

68. Types of Clouds Middle Clouds Moisture in the Atmosphere –Altocumulus and altostratus clouds, which form at heights between 2000 m and 6000 m, can be either all liquid or a mixture of liquid and ice crystals. –Middle clouds are usually layered. –Altocumulus clouds often resemble white fish scales. –Altostratus clouds are dark but thin veils of clouds that sometimes produce mild precipitation.

69. Types of Clouds Moisture in the Atmosphere

70. Types of Clouds High Clouds Moisture in the Atmosphere –Because they form above heights of 6000 m, where temperatures are below freezing, high clouds are made up of ice crystals. –Cirrus clouds, often have a wispy, indistinct appearance. –Cirrostratus clouds form as a continuous layer that sometimes covers the sky. –Cirrostratus clouds can vary in thickness from being almost transparent to being dense enough to block out the Sun or Moon.

71. Types of Clouds Moisture in the Atmosphere

72. Types of Clouds Clouds of Vertical Development Moisture in the Atmosphere –If the air that makes up a cumulus cloud is unstable enough, the cloud will continue to grow. –As it rises, water vapor condenses, and the air receives additional warmth from the release of latent heat. –If conditions are right, it can reach nearly 18,000 m. –A cumulus cloud can thus develop into a full-fledged cumulonimbus that is capable of producing the torrential rains and strong winds that are characteristic of thunderstorms.

73. Types of Clouds Moisture in the Atmosphere

74. Precipitation Coalescence occurs when cloud droplets collide and join together to form a larger droplet. Moisture in the Atmosphere When the droplet becomes too heavy to be held aloft, gravity takes over and it falls to Earth as precipitation. Precipitation includes all forms of water, both liquid and solid, that fall from clouds including rain, snow, sleet, and hail. Coalescence is the primary process for the formation of precipitation from warm clouds. Precipitation from cold clouds generally involves interaction of ice and water molecules in clouds.

75. The Water Cycle At any one time, only a small percentage of water is present in the atmosphere. Moisture in the Atmosphere This water continually moves between the atmosphere and Earth’s surface. The water cycle is the constant movement of water between the atmosphere and Earth’s surface. Evaporation is the process of water changing from a liquid to a gas.

76. The Water Cycle Moisture in the Atmosphere

77. Section Assessment 1.Match the following terms with their definitions. ___ condensation nuclei ___ stability ___ coalescence ___ latent heat Moisture in the Atmosphere A. process by which cloud droplets collide and join together to form a larger droplet B. small particles in the atmosphere around which cloud droplets can form C. stored energy in water vapor that is not released to warm the atmosphere until condensation takes place D. the ability of an air mass to resist rising B D A C

78. Section Assessment 2.What is the source of energy that fuels the water cycle? Moisture in the Atmosphere The water cycle receives its energy from the Sun’s radiation.

79. Section Assessment Moisture in the Atmosphere 3.How can latent heat affect the weather? When latent heat is released during condensation, it can provide energy to a weather system, thereby increasing its intensity.

80. Unit 6/7: The Atmosphere and the Oceans Chapter 11 Summary

81. Chapter Resources Menu Study Guide Section 11.1 Section 11.2 Section 11.3 Chapter Assessment

82. Section 11.1 Main Ideas Earth’s atmosphere is made of a combination of several gases, primarily nitrogen and oxygen. It also contains small amounts of water vapor, carbon dioxide, ozone, and dust, which play key roles in the production of weather and climate. The atmosphere consists of several layers characterized by differences in temperature. The most important for weather is the lowest layer, the troposphere, where most of the mass of the atmosphere is found. The Sun is the source of energy in Earth’s atmosphere. Solar energy absorbed by Earth’s surface is transferred throughout the atmosphere by the processes of radiation, conduction, and convection. Section 11.1 Study Guide

83. Section 11.2 Main Ideas Heat is the transfer of energy that occurs because of a difference in temperature between substances. Temperature is the measure of how rapidly or slowly molecules move around. Atmospheric temperature generally decreases with altitude. Air has mass and exerts a force called atmospheric pressure. Because there are fewer molecules of gas in the upper atmosphere, atmospheric pressure decreases with increasing altitude. Wind is the movement of air that results from differences in pressure. Wind speed is affected by friction; mountains, forests, and buildings slow wind down. Section 11.2 Study Guide

84. Section 11.3 Main Ideas Clouds are formed as warm, moist air is forced upward, expands, and cools. Orographic lifting is a method of cloud formation that involves air moving up the side of a mountain. Clouds may also form when air masses of different temperatures collide. Clouds are generally classified according to the altitudes at which they form and their shapes. As cloud droplets collide, they coalesce into larger droplets, which may fall to Earth as precipitation. The four main types of precipitation are rain, snow, sleet, and hail. In the water cycle, water continually moves between Earth’s surface and the atmosphere through the processes of evaporation, condensation, and precipitation. Section 11.3 Study Guide

85. 1.Which of the following gasses makes up the largest percentage of the atmosphere? a.oxygenc.nitrogen b.carbon dioxided.hydrogen Multiple Choice Chapter Assessment Nitrogen makes up 78 percent of the gases in Earth’s atmosphere. Oxygen makes up 21 percent. Carbon dioxide and hydrogen make up part of the remaining one percent.

86. 2.In which layer of the atmosphere contains the ozone layer? a.tropospherec.mesosphere b.stratosphered.thermosphere The ozone layer is found 20–50 km above Earth’s surface placing it below the stratopause in the stratosphere. Multiple Choice Chapter Assessment

87. Multiple Choice 3.You plan to climb 1500 m up a mountain on a sunny day. What temperature drop should be expected during your climb? a.5ºCc.15ºC b.10ºCd.20ºC Chapter Assessment Since you will not be climbing high enough to reach the lifted condensation level which would be marked by clouds, you should use the dry adiabatic lapse rate (10ºC per 1000 m) to figure temperature drop.

88. Multiple Choice 4.Which atmospheric phenomenon would most likely aid in smog formation? a.temperature inversionc.conduction b.orographic liftingd.convection Chapter Assessment A temperature inversion can act like a lid to trap pollution under the inversion layer. Orographic lifting, conduction, and convection all help to mix the atmosphere.

89. Multiple Choice 5.Which of the following is a cloud of vertical development? a.altocumulusc.nimbostratus b.cumulonimbusd.stratocumulus Chapter Assessment Cumulonimbus clouds begin as cumulus clouds and can reach more than 18 000 m into the atmosphere. They are associated with thunderstorms and sometimes have a classic anvil-shaped top.

90. Short Answer 6.Explain the relationship between air temperature and density. Chapter Assessment The relationship between temperature and density is inversely proportional. If an air mass maintains a certain pressure, as temperature increases, density decreases, and as temperature decreases, pressure increases. Air rises when its temperature increases because it is less dense.

91. Short Answer 7.Why does Earth’s surface play a larger role in warming the atmosphere than direct solar radiation? Chapter Assessment Solar radiation that travels through the atmosphere does so at short wavelengths that are not easily absorbed by the atmosphere but are absorbed by Earth’s surface. The surface then radiates energy back at longer wavelengths that can be absorbed by the atmosphere. The air is then warmed through the processes of conduction and convection.

92. True or False 8.Identify whether the following statements are true or false. ______ 100ºF is equal to 373 K. ______ Most weather occurs in the troposphere. ______If the amount of water vapor in the air stays the same as the temperature rises, relative humidity decreases. ______ Latent heat causes the evaporation that fuels the water cycle. ______ Conduction affects only a very thin atmospheric layer near Earth’s surface. Chapter Assessment false true false true

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