9th Period Environmental Science Chapter 15: The Atmosphere

Transcription

1 Section 15.1: Earth s Atmosphere 9th Period Environmental Science Chapter 15: The Atmosphere Properties of the Atmosphere: nitrogen, oxygen, water vapor and 1% other gases. air pressure is higher at the bottom Atmosphere is a thin layer of gases that surrounds the earth Relative humidity- ratio of water vapor in the air contains to the max amount it could have at that temp. air pressure: atmospheric pressure,the force exerted by air on the area below. Layers of the Atmosphere Troposphere lowest layer of atmosphere, directly above the ground contains oxygen we need to live responsible for Earth s weather 3/4 of atmosphere s mass, but the thinnest layer, too the higher in the air of the troposphere, the cooler it is Stratosphere layer above Troposphere km (7-31 miles) above sea level highest part of the Stratosphere is warmer than the lower levels of the Stratosphere maximum temp of -3* C(27* F) at the highest altitude O3 = ozone ozone layer is part of the stratosphere ozone filters out uv rays ozone is a pollutant in the Troposphere Mesosphere and Thermosphere Mesosphere extends km above sea level, the temperature decreases with the altitude, and has very low air pressure Thermosphere begins 80 km above surface and extends into space, it has very thin air, and temperature is very high The Troposphere and Weather Vocabulary Words Radiation: Transfer of energy through space. Conduction: Is the transfer of heat directly between two objects that are in contact with one another. Convection: Is the transfer of heat by the movement of currents within a fluids Convection Currents: Sinking cool air and rising warm air (Convection currents cause winds and move heat through the troposphere).

2 Air Mass: Large body of air, properties such as temperature, pressure, and humidity are similar. Front: The boundary between air masses that differ in temperature and moisture. Weather: Refers to atmospheric conditions over short time periods. Climate: Describes the pattern of atmospheric conditions in large geographic regions over long periods. Radiation Energy from the sun heats the atmosphere Heat is transferred in 3 ways, Radiation, conduction, and convection. When objects are heated by radiation, there is no direct contact between heat sources and the object being heated Dark objects absorb more radiation than objects that are light in color. Light objects reflect much more radiation. Conduction Conduction occurs when molecules collide, and energy is transferred from one molecule to another. In the troposphere, conduction only occurs between earth s surface and the molecules in the air directly in contact with it. Convection In fluids, molecules are free to move around. Convection is an important method of heat transfer. Convection currents and the movement of heat Process of convection is related to density. When air near the surface of earth is heated, it becomes less dense than it was before. Because of this difference in density, cool air sinks and warm air rises. Air masses and Fronts Warm Front: Boundary along which mass of warmer, moisture air pushes against a mass of colder, drier air. Cool air can hold less moisture than warm air can, the water vapor in the cooler air condenses are forms clouds. Light rain could fall Cold Front: Cooler air is denser than warm air, the cold air tends to wedge beneath the warm air.

3 Cold fronts can cause a sudden weather change. Once a cold front goes through an area, the sky usually clears, and the temperature and humidity drop. Section 15.2: Pollution of the Atmosphere Sources of Air Pollution Air pollution- The release of damaging materials into the atmosphere. -caused by both human activities and natural processes - the substances released are called emissions -some are tiny particles ( such as smoke, and soot) -some are gases (like sulfur dioxide and carbon monoxide) Natural processes of air pollution -Produces a great deal of the world s air pollution Ex. Winds can create huge dust storms, volcanic eruptions release tiny particles and gases into the atmosphere, fires produce smoke and gases -Human activities can make natural pollution worse Ex. Farming can lead to wind erosion which can lead to dust storms Human sources -The way we live introduces many sources of air pollution Ex. Our industries, the cars we drive, and the way we produce electricity -It can be point source or nonpoint source -Most pollution comes from combustion of fossil fuels- carbon containing fuels that form millions of years ago from the remains of living things Ex. Motor vehicles run by burning fossil fuels and release an enormous amount of pollutants into the air Primary and Secondary Air Pollutants -Primary air pollutants- pollutants released directly into the troposphere (such as soot and air pollution) -May cause damage themselves or they may react with other products to cause damage -Secondary air pollutants-harmful products produced when primary air pollutants react chemically with other substances (include tropospheric ozone and sulfuric acid) How Air Pollutants Affect Your Health Harmful respiratory conditions, such as asthma, bronchitis, and emphysema, can develop from continuous exposure to air pollution. Air pollutants can damage the respiratory system, interfere with the body s uptake of oxygen, and cause cancer. The Effect of Carbon Monoxide: The cells in your body obtain the oxygen they need by inhaling air that

4 contains oxygen which passes into the bloodstream. Hemoglobin, contained in red blood cells, is a molecule that combines chemically with oxygen to carry this oxygen to the rest of the body. If Carbon Monoxide is present in the air that is inhaled, it will bind to the hemoglobin, reducing the amount of oxygen blood cells normally would be able to carry. In high concentrations, Carbon Monoxide can be fatal. Cancer-Causing Pollutants: Trace amounts of pollutants found in the air may cause cancer in inhaled frequently. Benzene is an organic compound in gasoline which may be linked to cancer. Smog and Temperature Inversions Smog is an unhealthy mixture of air pollutants that may form over cities and their surrounding areas. Smog is produced when soot combines with sulfur compound and water droplets in the air. Industrial technologies that are used in developing nations (China) are older than that in developed nations (United States), and for that reason, developing countries have less ability to control air pollution and less government regulation. Photochemical Smog: Photochemical processes need light. Photochemical smog is a thick, brownish haze that forms when sunlight acts on certain air pollutants (ex: nitrogen oxides or hydrocarbons). The main source of the pollutants in photochemical smog is the exhaust released by cars and trucks. An example of an effort made to reduce the emissions that create this smog is government regulated motor-vehicle inspections, also known as e-check. In the troposphere (lowest layer of the atmosphere), air temperature usually decreases as altitude increases. Because warm air rises, pollutants are carried from low altitudes high into the troposphere. A temperature inversion is the condition in which a layer of cooler air is located beneath a layer of warmer air in the troposphere. Cold air has a greater density than warmer air - air at Earth s surface does not mix with other air allowing air pollutants to be prevalent. Acid Deposition Acid deposition results when some pollutants combine with water, oxygen, and other chemicals in the atmosphere. Pollutants mix with elements in the atmosphere to form compounds called acids -- which settle to the surface of the Earth as acid deposition. Acid precipitation is sometimes referred to as acid rain, but any kind of precipitation (snow,sleet) can contain acidic pollutants. The ph scale is used to measure whether solutions are acidic or alkaline (basic), with scale values ranging 0 to 14. A ph of 7 is neutral, ph greater than 7 is basic, and a ph less than 7 is acidic. Normal precipitation is slightly acidic, with a ph of approximately 5.6. Section 15.3: Controlling Air Pollution

5 Goal of the Clean Air Act: Clean Air Act: Protects and improves the quality of air in order to safeguard human health and the environment. ~The law takes measures to reduce the emission of pollutants that cause health problems such as asthma and cancer. ~The law limits the release of pollutants for environmental problems such as smog and acid deposition. Provisions of the Clean Air Act: ~The act limits emissions of pollutants by motor vehicles and industries. ~It sets standards for air quality ~It lets people sue industries that break the rules ~It sets aside fund for research into pollution control Under the Clean Air Act the U.S. Environmental Protection Agency (EPA) sets nationwide standards governing air pollutants and air quality. The states and Native American tribes have the option of developing and enforcing specific regulations that are equivalent to-or exceed- those found in the Clean Air Act. Reduction in Air Pollutants: ~Since the act the worst of the air pollutants has gone down 57% ~The reduction of outdoor air pollution is one of the nation s greatest accomplishments in protecting the environment. ->Motor Vehicles: Cars and trucks now cause less pollution. ~Catalytic converters have helped bring this to life. ~Catalytic Converters is a devise in a motor vehicle that reduces the amount of air pollution in emissions. ~It changes carbon monoxide into carbon dioxide and water. Since 1975 all new cars in the United States have catalytic converters. ->Cleaner Gasoline: Gasoline contained lead at one point, and was part of the emissions from the exhaust system of cars. ~Lead from car emission can settle to the ground and contaminate it. ~ If lead gets into the bloodstream of a person-especially a young child-it can cause behavioral disorders to mental retardation. ~The EPA has been working to phase out lead in gasoline since 1973, and today gasoline used by cars and trucks contain almost no lead. ->Industries and Power Plants: From the Clean Air Act industries and power plants have been required to reduce the amount of pollutants they release. ~Scrubbers are responsible for much of this reduction

6 ~Scrubber removes pollutants or change them chemically before they leave a factories smokestacks. Ozone: A Success Story Gases in Atmosphere: Ozone is type of smog in the troposphere that blocks out harmful ultraviolet radiation Ozone hole is an area of lowered ozone in Antarctica that occurs August to October. A problem is that the ozone is starting to deplete because there are certain things such as CFCs that are destroying the ozone layer what CFCs are is chlorine fluorine and carbon these can be used in many ways like aerosol cans and what happens is when it gets into the air it starts to destroy the ozone layer The Montreal protocol is one thing that the US tried to stop making stuff with CFCs in them so it would stop destroying the ozone.