| A | B |
|---|
| Atmosphere | The mass of air surrounding a planet |
| Atmospheric pressure | The pressure exerted by the atmosphere on all objects within it |
| Barometer | An instrument used to measure atmospheric pressure |
| Heterosphere | The upper layer of earth's atmosphere, which exists higher than roughly 80 kilometers (50 miles) above sea level |
| Homosphere | The lower layer of earth's atmosphere, which exists from ground level to roughly 80 kilometers (50 miles) above sea level |
| Troposphere | The region of the atmosphere that extends from ground level to roughly 11 kilometers (7 miles) above sea level |
| Stratosphere | The region of the atmosphere that spans altitudes of roughly 11 kilometers to 48 kilometers (30 miles) |
| Mesosphere | The region of the atmosphere that spans altitudes of roughly 48 kilometers to 80 kilometers (50 miles) |
| Jet streams | Narrow bands of high-speed winds that circle the earth, blowing from west to east |
| Heat | Energy that is transformed as a consequence of temperature differences |
| Temperature | A measure of the energy of random motion in a substance's molecules |
| Thermosphere | The region of the atmosphere between altitudes of roughly 80 kilometers and 460 kilometers |
| Exosphere | The region of the atmosphere above an altitude of roughly 460 kilometers |
| Ionosphere | The region of the atmosphere between the altitudes of roughly 65 kilometers and 330 kilometers, where the gases are ionized |
