| A | B |
|---|
| atmosphere | the envelope of gases that surround the planet |
| weather | the condition of Earth's atmosphere at a given time and place |
| 78% | amount of nitrogen in dry air |
| 21% | amount of oxygen in dry air |
| water vapor | water in the form of a gas |
| steam | made up of tiny droplets of liquid water |
| oxygen | necessary for respiration |
| ozone layer | absorbs UV rays |
| temperature | used to distinguish layers of Earth's atmosphere |
| troposphere | layer closest to Earth's surface |
| troposphere | weather happens here |
| stratosphere | contains the ozone layer |
| mesophere | meteoroids burn up here |
| ionosphere | Aurora borealis happen here |
| exosphere | communication satellites orbit here |
| thermosphere | made up of ionosphere and exosphere |
| thermosphere | extends into outerspace (no definite outer limits) |
| troposphere | temperatures decrease with altitude |
| stratosphere | temperatures increase with altitude |
| altitude | height above Earth's surface |
