| A | B |
|---|
| troposphere | the level in which human beings live |
| mesosphere | the layer between the stratosphere and thermosphere |
| exosphere | where the space shuttle would be |
| thermosphere | the ionosphere is here |
| stratosphere | the protective layer that contains ozone |
| ionosphere | a layer of charged particles in the thermosphere |
| ionosphere | particles there allow radio waves to travel far distances |
| ozone layer | absorbs most of the Sun's harmful ultraviolet radiation |
| atmosphere | air surrounding the Earth |
