| A | B |
|---|
| acid deposition | water vapor containing acids that falls to the ground as rain, snow, sleet, or hail |
| air mass | a large body of air in which properties such as temperature, pressure, and humidity are similar |
| air pollution | the release of damaging materials into the atmosphere |
| air pressure | the force exerted by air on the area below it |
| atmosphere | the thin layer of gases that surrounds Earth |
| catalytic converter | a device in a motor vehicle that reduces the amount of pollutants in emissions |
| chlorofluorocarbon | a chemical compound developed for use in refrigeration and spray can propellants |
| Clean Air Act | an act that sets strict standards for air quality and strengthens the government's ability to enforce regulations |
| conduction | the transfer of heat directly between two objects that are in contact with each other |
| convection | the transfer of heat in a fluid as warm parts of the fluid rise from the heat source and expand |
| convection current | the movement in a fluid as warm parts of the fluid rise and cool parts sink |
| emission | a substance that is released into the atmosphere |
| fossil fuel | a carbon-containing fuel formed over millions of years from the remains of living things |
| front | the boundary between air masses that differ in temperature and moisture |
| mesosphere | the layer of the atmosphere that extends 50 to 80 km above sea level |
| Montreal Protocol | a treaty that limits the production of chlorofluorocarbons |
| ozone hole | the area of lowered ozone concentration over Antarctica |
| ozone layer | the concentration of ozone in the stratosphere |
| primary air pollutant | a pollutant released directly into the troposphere |
| radiation | the transfer of energy through space |
| relative humidity | the ratio of water vapor in the air to the maximum amount of water vapor the air could hold at that temperature |
| scrubber | a device that removes pollutants or changes them chemically before they leave factor smokestacks |
| secondary air pollutant | a harmful substance produced when a primary pollutant reacts with other substances |
| smog | an unhealthy mixture of air pollutants that can form over cities and nearby areas |
| stratosphere | the layer of the atmosphere that extends 11 to 50 km above sea level |
| temperature inversion | the condition in the troposphere in which a layer of cooler air lies beneath a layer of warmer air |
| thermosphere | the top layer of the atmosphere that extends from 80 km above sea level indefinitely into space |
| troposphere | the lowest layer of the atmosphere that extends 0 to 11 km above sea level |
