| A | B |
|---|
| evaporation | The process by which molecules at the surface of a liquid, such as water, absorb enough energy to change to a gaseous state, such as water vapor |
| humidity | A measure of the amount of water vapor in the air. |
| relative humidity | The percentage of water vapor in the air compared to the maximum amount the air can hold at that temperature. |
| psychrometer | An instrument used to measure relative humidity, consisting of a wet-bulb thermometer and a dry-bulb thermometer. |
| condensation | The process by which a gas, such as water vapor, changes to a liquid, such as water. |
| dew point | The temperature at which condensation begins. |
| cumulus | Clouds that form less than 2 kilometers above the ground and look like fluffy, rounded piles of cotton. |
| stratus | Clouds that form in flat layers. |
| cirrus | Wispy, feathery clouds made mostly of ice crystals that form at high levels, above about 6 kilometers. |
