23 terms

Chapter 18 Moisture Clouds & Precipitation

Chapter 18 Moisture, Clouds, and Precipitation
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precipitation
any form of water that falls from a cloud
latent heat
the energy absorbed or released during a change in state
evaporation
the process of converting a liquid to a gas
condensation
the change of state from a gas to a liquid
sublimation
the conversion of a solid directly to a gas without passing through the liquid state
deposition
the process by which water vapor is changed directly to a solid without passing through the liquid state
humidity
general term referring to water vapor in the air but not to liquid droplets of fog, cloud, or rain
saturated
the state of air that contains the maximum quanity of water vapor that it can hold at any given temperature and pressure
relative humidity
the ratio of the air's water-vapor content to its water-vapor capacity
dew point
the temperature to which air has to be cooled in order to reach saturation
hygrometer
an instrument designed to measure relative humidity
dry adiabatic rate
the rate of adiabatic cooling or warming in unsaturated air; the rate of temperature change is 1 degree Celsius per 100 meters
wet adiabatic rate
the rate of adiabatic temperature change in saturated air; the rate of temperature change is variable, but it is always less dry that the dry adiabatic rate
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
front
the boundary between two adjoining air masses having contrasting characteristics
temperature inversion
a layer of limited depth in the atmosphere of limited depth where the temperature increases rather than decreases with height
condensation nuclei
tiny bits of particulate matter that serve as surfaces on which water vapor condenses
cirrus
one of three basic cloud forms; they are thin delicate ice-crystal clouds often appearing as veil-like patches or thin, wispy fibers
stratus
one of three basic cloud forms, they are sheets or layers that cover much or all of the sky
Bergeron process
a theory that rates the formation of precipitation to supercooled clouds, freezing nuclei, and the different saturation levels of ice and liquid water
supercooled water
the condition of water droplets that remain in the liquid state at temperatures well below 0 degrees Celsius
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
collision-coalescence process
a theory of raindrop formation in warm clouds ( above 0 degrees Celsius) in which large cloud droplets collide and join together with smaller droplets to form a raindrop; Opposite electrical charges may bind the clouds together