| A | B |
|---|
| air pollution | a change to the atmosphere that has harmful effects |
| acid rain | rain that is more acidic than normal; caused by the release of molecules of sulfer dioxide into the air |
| catalytic converter | a device that reduces carbon monoxide emissions from vehicles |
| condensation | the process by which a gas, such as water vapor, changes into a liquid, such as water |
| chloroflourocarbons | chlorine compounds formerly used in air conditioners,refrigerators, and spray cans |
| drought | a water shortage caused by long periods of low precipitation in a particular area |
| emissions | particles and gases released into the air from a smokestack or motor vehicle |
| evaporation | the process by which molecules at the surface of a liquid absorb enough energy to change to a gaseous state |
| fertilizer | a chemical that provides nutrients to help crops grow better |
| groundwater | water that fills the cracks and spaces in underground soil and rock layers |
| ozone | a form of oxygen that has three atoms in each molecule instead of the usual two;can be toxic |
| ozone layer | a form of the atmosphere that contains a higher concentration of ozone than the rest of the atmosphere |
| pesticide | a chemical intended to kill insects and other organisms that damage crops |
| photochemical smog | a brownish haze that is a mixture of ozone and other chemicals, formed when nitrogen oxides,hydrocarbons and other pollutants react with one another in the presence of sunlight |
| primary treatment | the removal of solid materials from wastewater |
| secondary treatment | the use of bacteria to break down wastes in wastewater |
| sediment | small,solid pieces of material from rocks or organisms which are moved by water or wind,resulting in erosion and deposition |
| scrubber | a device that uses water dropletts to clean smokestack emissions |
| temperature inversion | condition in which a layer of warm air traps polluted air close to Earth's surface |
| water cycle | the continuous process by which water moves from Earth's surface and to the atmosphere and back, passing through the living and nonliving parts of the environment |
| water pollution | the addition of any substance that has a negative effect on water or on the living things that depend on the water |
| sewage | water containing human waste |
