| A | B |
|---|
| Bergeron process | a theory that relates the formation of precipitation to supercooled clouds, freezing nuclei, and the different saturation levels of ice and liquid water |
| cirrus | one of three basic cloud forms; also one of the three high cloud types; They are thin, delicate ice-crystal clouds often appearing as veil-like patches or thin, wispy fibers. |
| collision-coalescence process | a theory of raindrop formation in warm clouds (above 0°C) in which large cloud droplets collide and join together with smaller droplets to form a raindrop; Opposite electrical charges may bind the cloud droplets together. |
| condensation | the change of state from a gas to a liquid |
| condensation nuclei | tiny bits of particulate matter that serve as surfaces on which water vapor condenses |
| cumulus | one of three basic cloud forms; also the name given to one of the clouds of vertical development; They are billowy individual cloud masses that often have flat bases. |
| deposition | the process by which an agent of erosion loses energy and drops the sediment it is carrying; also the process by which water vapor is changed directly to a solid without passing through the liquid state |
| dew point | the temperature to which air has to be cooled in order to reach saturation |
| dry adiabatic rate | the rate of adiabatic cooling or warming in unsaturated air; The rate of temperature change is 1°C per 100 meters. |
| evaporation | the process of converting a liquid to a gas |
| front | the boundary between two adjoining air masses having contrasting characteristics |
| humidity | a general term referring to water vapor in the air but not to liquid droplets of fog, cloud, or rain |
| hygrometer | an instrument designed to measure relative humidity |
| latent heat | the energy absorbed or released during a change in state |
| orographic lifting | mountains acting as barriers to the flow of air, forcing the air to ascend; The air cools adiabatically, and clouds and precipitation may result. |
| precipitation | any form of water that falls from a cloud |
| relative humidity | the ratio of the air’s water-vapor content to its water-vapor capacity |
| saturated | the state of air that contains the maximum quantity of water vapor that it can hold at any given temperature and pressure |
| stratus | one of three basic cloud forms; They are sheets or layers that cover much or all of the sky. |
| sublimation | the conversion of a solid directly to a gas without passing through the liquid state |
| supercooled water | the condition of water droplets that remain in the liquid state at temperatures well below 0°C |
| supersaturated air | the condition of air that is more highly concentrated than is normally possible under given temperature and pressure conditions; When describing humidity, it refers to a relative humidity that is greater than 100 percent. |
| temperature inversion | a layer of limited depth in the atmosphere of limited depth where the temperature increases rather than decreases with height |
| wet adiabatic rate | the rate of adiabatic temperature change in saturated air; The rate of temperature change is variable, but it is always less than the dry adiabatic rate. |
