| A | B |
|---|
| atmosphere | the covering of gases that surround the earth |
| barometer | an instrument used to measure air pressure |
| elevation | the distance above sea level |
| tropopause | the outer section of the troposphere |
| troposphere | the layer of atmosphere closest to earth's surface |
| matter | anything with mass and volume |
| relative humidity | amount of water vapor compared to the capacity |
| ionosphere | layer of the atmosphere that reflects radio waves back to earth |
| conduction | the movement of energy through solids |
| convection | the movement of energy through empty space |
| radiation | the movement of energy through liquids and gases |
| continental air mass | an air mass formed over land |
| maritime air mass | an air mass formed over water |
| tropical air mass | an air mass formed over warm area (equator) |
| polar air mass | an air mass formed over cold areas (polar regions) |
| air mass | a very large body of air with the same pressure, temperature and humidity |
| isobars | lines on a map used to show the same air pressure |
| weather front | the boundary where air masses meet |
| humidity | the amount of water vapor in the air |
| condensation | water vapor changing to its liquid state |
| dew point | the temperature at which air must be cooled to reach saturation |
| anemometer | an instrument that measures wind speed |
