| A | B |
|---|
| weather | the condition of Earth's atmosphere at a particular time and place |
| atmosphere | the layer of gases that surrounds the planet |
| ozone | a form of oxygen that has three oxygen atoms in each molecule instead of the usual two |
| water vapor | water in the form of a gas |
| pollutants | harmful substances in the air, water, or soil |
| photochemical smog | the brown haze that forms in cities |
| acid rain | rain that contains more acid than normal |
| density | the amount of mass in a given volume of air |
| pressure | the force pushing on an area or surface |
| barometer | an instrument that is used to measure changes in air pressure |
| altitude | elevation upon sea level |
| troposphere | the lowest layer of Earth's atmosphere where weather occurs |
| stratosphere | the second-lowest layer of Earth's atmosphere;the ozone is located there |
| mesosphere | the middle layer of Earth's atmosphere;the layer in which most meteoroids burn up |
| thermosphere | the outermost layer of Earth's atmosphere |
| ionosphere | the lower layer of the thermosphere, where electrically charged particles are found |
| aurora borealis | the Northern Lights |
| exosphere | the outer layer of the thermosphere extending outward into space |
