Chapter Introduction Lesson 1 Lesson 2 Lesson 3 Lesson 4 Earth s Atmosphere Energy Transfer in the Atmosphere Air Currents Air Quality Chapter Wrap-Up
How does Earth s atmosphere affect life on Earth?
What do you think? Before you begin, decide if you agree or disagree with each of these statements. As you view this presentation, see if you change your mind about any of the statements.
Do you agree or disagree? 1. Air is empty space. 2. Earth s atmosphere is important to living organisms. 3. All the energy from the Sun reaches Earth s surface. 4. Earth emits energy back into the atmosphere.
Do you agree or disagree? 5. Uneven heating in different parts of the atmosphere creates air circulation patterns. 6. Warm air sinks and cold air rises. 7. If no humans lived on Earth, there would be no air pollution. 8. Pollution levels in the air are not measured or monitored.
Earth s Atmosphere How did Earth s atmosphere form? What is Earth s atmosphere made of? What are the layers of the atmosphere? How do air pressure and temperature change as altitude increases?
Earth s Atmosphere atmosphere water vapor troposphere stratosphere ozone layer ionosphere
Importance of Earth s Atmosphere The atmosphere is a thin layer of gases surrounding Earth. The atmosphere contains the oxygen and water necessary for life on Earth. The atmosphere provides insulation and helps keep temperatures on Earth within a range in which living organisms can survive.
Importance of Earth s Atmosphere (cont.) The atmosphere helps protect living organisms from some of the Sun s harmful rays and meteorites. atmosphere from Greek atmos, means vapor ; and Latin sphaera, means sphere
Origins of Earth s Atmosphere Erupting volcanoes emitting hot gases from ancient Earth s interior surrounded the planet to form an atmosphere. Ancient Earth s atmosphere was thought to be water vapor with a little carbon dioxide and nitrogen, but not enough oxygen to support life. Water vapor is water in gaseous form.
Origins of Earth s Atmosphere (cont.) As Earth and its atmosphere cooled, the water vapor condensed into liquid, rain fell, and then evaporated from Earth s surface for thousands of years. Eventually water began to accumulate on Earth s surface, forming oceans. Earth s first organisms could undergo photosynthesis, which changed the atmosphere.
Origins of Earth s Atmosphere (cont.) The organisms removed CO 2 from the atmosphere and released oxygen into it. Eventually the levels of CO 2 and oxygen supported the development of other organisms.
Origins of Earth s Atmosphere (cont.) How did Earth s present atmosphere form?
Composition of the Atmosphere Today s atmosphere is mostly made up of invisible gases, including nitrogen, oxygen, and carbon dioxide. About 78 percent of the atmosphere is nitrogen, and about 21 percent is oxygen. The amounts of water vapor, carbon dioxide, and ozone vary.
Acids in the air are formed when sulfur dioxide and nitrous oxide combine with water vapor. PhotoLink/Getty Images
Composition of the Atmosphere (cont.) Many tiny solid particles, such as pollen, dust, and salt, can enter the atmosphere through natural processes. Solid particles of ash from volcanic eruptions and exhaust soot from cars are also present in the atmosphere.
One way solid particles enter the atmosphere is from volcanic eruptions. C. Sherburne/PhotoLink/Getty Images
Composition of the Atmosphere (cont.) The most common liquid particles in the atmosphere are water droplets. Though microscopic in size, water particles are visible when they form clouds. Other atmospheric liquids include acids that result when volcanoes erupt and fossil fuels are burned.
Composition of the Atmosphere (cont.) Acids in the air are formed when sulfur dioxide and nitrous oxide combine with water vapor. What is Earth s atmosphere made of?
Layers of the Atmosphere The atmosphere has several different layers, each with its own unique properties.
Layers of the Atmosphere (cont.) The atmospheric layer closest to Earth s surface is called the troposphere. The troposphere extends from Earth s surface to altitudes between 8-15 km. The temperature of the troposphere decreases as you move away from Earth.
Layers of the Atmosphere (cont.) Sunlight passes through the atmosphere, warms Earth s surface, and the warmth is radiated to the troposphere, causing weather. The stratosphere is the atmospheric layer directly above the troposphere.
Layers of the Atmosphere (cont.) The stratosphere extends from about 15 km to about 50 km above Earth s surface. The area of the stratosphere with a high concentration of ozone is referred to as the ozone layer. The presence of the ozone layer causes the stratospheric temperatures to increase with altitude.
Layers of the Atmosphere (cont.) Ozone has three oxygen atoms and absorbs the Sun s ultraviolet rays more effectively than oxygen. Ozone protects Earth from ultraviolet rays that can kill plants, animals, and other organisms and cause skin cancer in humans.
Layers of the Atmosphere (cont.) Combined, the mesosphere and thermosphere are much thicker than the troposphere and the stratosphere, yet only 1 percent of the atmosphere s gas molecules are found in the mesosphere and thermosphere. Most meteors burn up in the mesosphere and thermosphere instead of striking Earth.
The ionosphere is a region within the mesosphere and thermosphere containing ions. The ionosphere s ions reflect AM radio waves transmitted at ground level.
Auroras occur in the ionosphere when ions from the Sun strike air molecules, causing them to emit vivid colors of light. Per Breiehagen/Getty Images
Layers of the Atmosphere (cont.) The exosphere is the atmospheric layer farthest from Earth s surface where pressure and density are so low that individual gas molecules rarely strike one another. The molecules move at incredibly fast speeds after absorbing the Sun s radiation and can escape the pull of gravity and travel into space.
Layers of the Atmosphere (cont.) What are the layers of the atmosphere?
Air Pressure and Altitude Gravity pulls the atmosphere toward Earth, creating air pressure. At higher altitudes, the air is less dense and air pressure is lower. At lower altitudes, the air is denser and air pressure is higher.
Temperature and Altitude Temperature changes in different ways as altitude increases in the different layers of the atmosphere. In the troposphere, temperature decreases as altitude increases. In the stratosphere, temperature increases as altitude increases because of the high concentration of ozone.
Temperature and Altitude (cont.) In the mesosphere, as altitude increases, temperature again decreases. In the thermosphere and exosphere, temperatures increase as altitude increases.
Temperature and Altitude (cont.) How does temperature change as altitude increases?
Earth s atmosphere consists of gases that make life possible. PhotoLink/Getty Images
Layers of the atmosphere include the troposphere, the stratosphere, the mesosphere, the thermosphere, and the exosphere. Per Breiehagen/Getty Images
The ozone layer is the area in the stratosphere with a high concentration of ozone.
Where did hot gases that created Earth s atmosphere come from? A. the Sun B. erupting volcanoes C. the air D. the ocean
What is about 78 percent of Earth s atmosphere made of? A. nitrogen B. oxygen C. ozone D. carbon dioxide
What is the region within the mesosphere and thermosphere containing ions? A. exosphere B. stratosphere C. ozone layer D. ionosphere
Do you agree or disagree? 1. Air is empty space. 2. Earth s atmosphere is important to living organisms.
Energy Transfer in the Atmosphere How does energy transfer from the Sun to Earth and the atmosphere? How are air circulation patterns within the atmosphere created?
Energy Transfer in the Atmosphere radiation conduction convection stability temperature inversion
Energy from the Sun Radiation is the transfer of energy by electromagnetic waves. Ninety-nine percent of the radiation from the Sun consists of visible light, ultraviolet light, and infrared radiation. The majority of sunlight is visible light that passes through the atmosphere to Earth s surface, where it is converted to heat.
Energy from the Sun (cont.) The wavelengths of ultraviolet (UV) light and infrared radiation (IR) are just beyond the range of visibility to human eyes. UV light is harmful to human skin and IR can be sensed as thermal energy or warmth. As energy from the Sun is absorbed by Earth, it is radiated back as IR.
Energy on Earth As Sun s radiation passes through the atmosphere, some of it is absorbed and some of it is reflected back into space. reflect Science Use to return light, heat, sound, etc., after it strikes a surface Common Use to think quietly and calmly
Energy on Earth (cont.) Gases and particles in the atmosphere absorb about 20 percent of incoming solar radiation. Oxygen, ozone, and water vapor all absorb incoming ultraviolet radiation. Water and carbon dioxide in the troposphere absorb some infrared radiation from the Sun.
Energy on Earth (cont.) About 30 percent of incoming radiation is reflected into space. Bright surfaces, especially clouds, reflect incoming radiation, and some is reflected at Earth s surface. Earth s surface only receives and absorbs about 50 percent of incoming solar radiation.
Radiation Balance The amount of radiation Earth receives from the Sun is the same as the amount Earth radiates into the atmosphere. This radiation balance maintains an overall temperature on Earth.
The Greenhouse Effect Some of the gases in the atmosphere, called greenhouse gases, act like the glass of a greenhouse, allowing sunlight to pass through but preventing some of Earth s IR energy from escaping. When gases in Earth s atmosphere direct radiation back toward Earth s surface, this warms Earth s atmosphere more than normal, creating a heat surplus.
The Greenhouse Effect (cont.) The gases that trap IR best are water vapor, carbon dioxide, and methane.
Thermal Energy Transfer Conduction occurs when the atmosphere touches Earth. Conduction is the transfer of thermal energy by collisions between particles of matter. Thermal energy always moves from an object with a higher temperature to an object with a lower temperature.
Thermal Energy Transfer (cont.) conduction from Latin conducere, means to bring together
Energy is transferred through conduction, convection, and radiation.
Thermal Energy Transfer (cont.) The transfer of thermal energy by the movement of matter from one place to another is called convection. As molecules of air close to Earth s surface are heated by conduction, they spread apart, becoming less dense. Less dense air rises, transferring thermal energy to higher altitudes.
Thermal Energy Transfer (cont.) Latent heat is exchanged when water changes from one phase to another. Water is the only substance that can exist as a solid, a liquid, and a gas at the temperature ranges on Earth. Latent heat energy is transferred from Earth s surface to the atmosphere.
Water releases or absorbs heat energy during phase changes.
Thermal Energy Transfer (cont.) How does energy transfer from the Sun to Earth and the atmosphere?
Circulating Air Air is constantly moving and circulating. On a hot day, air that is heated becomes less dense, creating a pressure difference. Cool, denser air pushes the warm air out of the way and the warm air is replaced by the more dense air. The warm air is often pushed upward.
Circulating Air (cont.) Warmer, rising air is always accompanied by cooler, sinking air. Circulating air affects weather and climate around the world. How are air circulation patterns within the atmosphere created?
Circulating Air (cont.) Stability describes whether circulating air motions will be strong or weak. When air is unstable, circulating motions are strong, and during stable conditions, circulating motions are weak. During unstable conditions, groundlevel air is much warmer than higheraltitude air.
Circulating Air (cont.) As warm air rises rapidly in the atmosphere, it cools to form large, tall clouds. Latent heat, released as water vapor, changes from a gas to a liquid, adds to the instability, and produces a thunderstorm. A temperature inversion occurs in the troposphere when temperature increases as altitude increases.
Circulating Air (cont.) During a temperature inversion, a layer of cooler air is trapped by a layer of warmer air above it.
Not all radiation from the Sun reaches Earth s surface. Thermal energy transfer in the atmosphere occurs through radiation, conduction, and convection.
Temperature inversions prevent air from mixing and can trap pollution in the air close to Earth s surface.
The transfer of thermal energy by the movement of matter from one place to another is called what? A. latent heat B. conduction C. convection D. the greenhouse effect
When air is unstable, circulating motions can usually be described how? A. strong B. weak C. absent D. warm
Which is exchanged when water changes from one phase to another? A. water vapor B. convection C. latent heat D. cool air
Do you agree or disagree? 3. All of the energy from the Sun reaches Earth s surface. 4. Earth emits energy back into the atmosphere.
Air Currents How does uneven heating of Earth s surface result in air movement? How are air currents on Earth affected by Earth s spin? What are the main wind belts on Earth?
Air Currents wind trade winds westerlies polar easterlies jet stream sea breeze land breeze
Global Winds Wind patterns can be global or local. There are great wind belts that circle the globe, and the energy that causes this massive movement of air originates at the Sun. Not all areas of Earth receive the same amount of energy from the Sun.
Global Winds (cont.) The differences in pressure between areas with low temperatures and high temperatures create wind. Wind is the movement of air from areas of high pressure to areas of low pressure.
Global Winds (cont.) How does uneven heating of Earth s surface result in air movement?
Global Wind Belts Three cells in each hemisphere move air through the atmosphere.
Global Wind Belts (cont.) In the first cell, hot air at the equator moves to the top of the troposphere then moves toward the poles until it cools and moves back to Earth s surface near the 30 latitude.
Global Wind Belts (cont.) The second cell, between 30 and 60 latitude, is not a convection cell because its motion is driven by the other two cells.
Global Wind Belts (cont.) The third cell, at the highest latitudes, is also a convection cell. Air from the poles moves toward the equator along Earth s surface, and warmer air is pushed upward by the cooler air near the 60 latitude.
Global Wind Belts (cont.) The three cells exist in both the Northern and Southern Hemispheres. Most of the air in this convection cell returns to the equator near Earth s surface.
Global Wind Belts (cont.) The Coriolis effect occurs when the rotation of Earth causes moving air and water to move to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The contrast between high and low pressure and the Coriolis effect creates distinct wind patterns, called prevailing winds.
Global Wind Belts (cont.) How are air currents on Earth affected by Earth s spin?
Global Wind Belts (cont.) The trade winds are steady winds that flow from east to west between 30 N latitude and 30 S latitudes. The prevailing westerlies are steady winds that flow from west to east between latitudes 30 N and 60 N, and 30 S and 60 S.
Global Wind Belts (cont.) The polar easterlies are cold winds that blow from the east to the west near the North Pole and the South Pole. What are the main wind belts on Earth?
Global Wind Belts (cont.) Located near the top of the troposphere is a narrow band of high winds called the jet stream. Jet streams influence weather as they move cold air from the poles toward the tropics and warm air from the tropics toward the poles.
Local Winds Local winds occur whenever air pressure is different from one location to another. A sea breeze is wind that blows from the sea to the land due to local temperature and pressure differences. A land breeze is a wind that blows from the land to the sea due to local temperature and pressure differences.
Sea breezes and land breezes are created as part of a large reversible convection current.
Wind is created by pressure differences between one location and another. Prevailing winds in the global wind belts are the trade winds, the westerlies, and the polar easterlies.
Sea breezes and land breezes are examples of local winds.
What does the difference in pressure between areas with low temperatures and those with high temperatures create? A. wind B. low pressure C. stability D. the Coriolis effect
What term refers to steady winds that flow from east to west between 30 N latitude and 30 S latitudes? A. prevailing westerlies B. jet streams C. polar easterlies D. trade winds
Which type of global winds move cold air from the poles toward the tropics and warm air from the tropics toward the poles? A. trade winds B. jet streams C. prevailing westerlies D. polar easterlies
Do you agree or disagree? 5. Uneven heating in different parts of the atmosphere creates air circulation patterns. 6. Warm air sinks and cold air rises.
Air Quality How do humans impact air quality? Why do humans monitor air quality standards?
Air Quality air pollution acid precipitation photochemical smog particulate matter
C. Sherburne/PhotoLink/Getty Images Sources of Air Pollution The contamination of air by harmful substances including gases and smoke is called air pollution. Point-source pollution is pollution that comes from an identifiable source such as large factories. An example of natural point-source pollution is an erupting volcano.
Sources of Air Pollution (cont.) Nonpoint-source pollution is pollution that comes from a wide-spread area, such as a large city. Some bacteria found in swamps and marshes are examples of natural sources of nonpoint-source pollution.
Sources of Air Pollution (cont.) Compare point-source and nonpoint-source pollution.
Causes and Effects of Air Pollution Acid precipitation occurs when sulfur dioxide and nitrogen oxides combine with moisture in the atmosphere and create acids that fall as precipitation. Acid precipitation can be in the form of rain, snow, and fog. It affects the chemistry of water in lakes and rivers and can harm organisms living in the water.
Causes and Effects of Air Pollution (cont.) Natural sources of sulfur dioxide include volcanoes and marshes. The most common sources of sulfur dioxide and nitrogen oxides are automobile exhausts and factory and power plant smoke. Photochemical smog is air pollution that forms from the interaction between chemicals in the air and sunlight.
Causes and Effects of Air Pollution (cont.) Smog forms when nitrogen dioxide, released in gasoline engine exhaust, reacts with sunlight. A series of chemical reactions produces ozone and other compounds that form smog. Ground-level ozone is the main component of smog.
Causes and Effects of Air Pollution (cont.) How do humans impact air quality?
Particulate Pollution Particulate matter is a mixture of dust, acids, and other chemicals that can be hazardous to human health. Particulate matter in the atmosphere absorbs and scatters sunlight, which can create haze.
Particulate Pollution (cont.) particulate from Latin particularis, means of a part
Movement of Air Pollution Because air carries pollution with it, some wind patterns cause more pollution problems than others. Weak winds or no wind prevents pollution from mixing with the surrounding air, which can create high pollution levels and dangerous conditions.
At night, cool air sinks down the mountain sides, trapping pollution in the valley below.
Maintaining Healthful Air Quality Preserving the quality of Earth s atmosphere requires the cooperation of government officials, scientists, and the public. The Clean Air Act gives the U.S. government the power to set air quality standards which protect humans, animals, crops, and buildings from the harmful effects of air pollution.
Maintaining Healthful Air Quality (cont.) Pollution levels are continuously monitored by hundreds of instruments in all major U.S. cities.
Air Quality Trends Air quality in U.S. cities has improved over the last several decades. Ground-level ozone has not decreased much, however, because as the number of cars on the road increases, air quality standards have not kept up with all pollutant levels.
Pollution emissions have declined, even though the population is increasing.
Air Quality Trends (cont.) The air inside homes and other buildings can be as much as 50 times more polluted than outdoor air and can impact human health much more than outdoor air quality. Indoor air pollution can come from tobacco smoke, cleaning products, pesticides, fireplaces, and radon an odorless gas given off by some soil and rocks.
Air Quality Trends (cont.) Why do humans monitor air quality standards?
C. Sherburne/PhotoLink/Getty Images Air pollution comes from point sources, such as factories, and nonpoint sources, such as automobiles. Photochemical smog contains ozone, which can damage tissues in plants and animals.
What is pollution that comes from a wide-spread area, such as a large city? A. smog B. haze C. nonpoint-source pollution D. point-source pollution
Which is a mixture of dust, acids, and other chemicals that can be hazardous to human health? A. photochemical smog B. acid precipitation C. sulfur dioxide D. particulate matter
What describes what has happened to air quality in U.S. cities over the last several decades? A. it has declined dramatically B. it has declined slightly C. it has improved D. it has remained the same
Do you agree or disagree? 7. If no humans lived on Earth, there would be no air pollution. 8. Pollution levels in the air are not measured or monitored.
Key Concept Summary Interactive Concept Map Chapter Review Standardized Test Practice
The gases in Earth s atmosphere help sustain life on Earth and regulate the cycling of thermal energy among Earth s systems.
PhotoLink/Getty Images Lesson 1: Earth s Atmosphere Earth s atmosphere formed as Earth cooled and chemical and biological processes took place. Earth s atmosphere consists of nitrogen, oxygen, and a small amount of other gases, such as CO 2 and water vapor. The atmospheric layers are the troposphere, the stratosphere, the mesosphere, the thermosphere, and the exosphere. Air pressure decreases as altitude increases. Temperature either increases or decreases as altitude increases, depending on the layer of atmosphere.
Lesson 2: Energy Transfer in the Atmosphere The Sun s energy is transferred to Earth s surface and the atmosphere through radiation, conduction, convection, and latent heat. Air circulation patterns are created by convection currents.
Lesson 3: Air Currents Uneven heating of Earth s surface creates pressure differences. Wind is the movement of air from areas of high pressure to areas of low pressure. Air currents curve to the right or to the left due to the Coriolis effect. The main wind belts on Earth are the trade winds, the westerlies, and the polar easterlies.
C. Sherburne/PhotoLink/Getty Images Lesson 4: Air Quality Some human activities release pollution into the air. Air quality standards are monitored for the health of organisms and to determine if anti-pollution efforts are successful.
Which is the atmospheric layer directly above the troposphere? A. stratosphere B. ionosphere C. exosphere D. atmosphere
Which describes the air at higher altitudes? A. more dense B. hot C. layered D. less dense
Which term refers to the transfer of thermal energy by collisions between particles of matter? A. conduction B. convection C. radiation D. circulation
The contamination of air by harmful substances including gases and smoke is called what? A. photochemical smog B. particulate matter C. air pollution D. ground-level ozone
Which describes air pollution that forms from interaction between chemicals in the air and sunlight? A. acid rain B. photochemical smog C. particulate matter D. nonpoint-source pollution
Which term refers to water in gaseous form? A. ozone B. nitrogen C. acid D. water vapor
Which term describes the thin layer of gases surrounding Earth? A. ozone layer B. atmosphere C. troposphere D. stratosphere
The transfer of energy by electromagnetic waves is called what? A. convection B. conduction C. radiation D. circulation
Which term refers to the movement of air from areas of high pressure to areas of low pressure? A. temperature inversion B. stability C. air pollution D. wind
Which describes air pollution that comes from an identifiable source such as large factories? A. point-source air pollution B. nonpoint-source air pollution C. photochemical smog D. acid precipitation