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51 terms

Ch 18 Sci-Moisture,clouds, precipitation

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precipitation 1
1. any form of water that falls from a cloud
precipitation 2
2. example - rain, sleet, and hail
water 1
1. can change from one state of matter to another at the temperatures and pressures experienced at Earth's surface
water 2
2. the processing of changing state requires that energy is transferred in the form of heat
water vapor 1
1. makes up 0 - 40% of atmospheric gases
water vapor 2
2. most important gas for understanding atmospheric processes
water vapor 3
3. the source of all condensation and precipitation
latent heat
refers to the energy that is stored or released during a change of state of water
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 changes directly to a solid
humidity
term for the amount of water vapor in the air
saturated 1
1. air that has reached its water-vapor capacity
saturated 2
2. warm, saturated air contains more water vapor than cold air
saturated 3
3. warm air is capable of holding more water vapor than cold air
relative humidity 1
1. the ratio of air's water-vapor content to its capacity to hold water vapor at the same temperature
relative humidity 2
2. indicates how near the air is saturated
relative humidity 3
3. when 2 temperatures read nearly the same on a psychrometer, the air will have a high relative humidity
relative humidity 4
4. if the water-vapor content of air remains constant, lowering air temperature will cause an increase in relative humidity
relative humidity 5
5. if the water-vapor content of air remains constant, raising air temperature will cause a decrease in relative humidity
dew point
the temperature to which air would have to be cooled to reach saturation
adiabatic
type of temperature change air experiences when the air expands or contracts
dry adiabatic state 1
1. the rate of cooling or heating that applies only to unsaturated air
dry adiabatic state 2
2. rate is 10 degrees Celsius/1000 meters
wet adiabatic state
rate of cooling is less than the dry rate because of the release of latent heat
compressed air
molecules move faster and air temperature rises
processes that lift air
orographic lifting, frontal wedging, convergence, localized convective lifting
orographic lifting
occurs when elevated terrains act as barriers to air flow; associated with mountains
frontal wedging
process by which cool air acts as a barrier over which warmer, less dense air rises
thermals
rising parcels of warm air; clothing put on in the winter to keep warm
stable air
tends to resist rising (remains in its original position)
unstable air
tends to rise
condensation nuclei 1
1. abundant in the lower atmosphere
condensation nuclei 2
2. Example - dust, smoke, salt particles
condensation
produces dew, fog, and clouds
clouds
classified on the basis of their form and height
cumulus
consists of globular cloud masses with a cauliflower structure
stratus
described as sheets or layers that cover much or all of the sky
nimbus
term that means "rainy cloud"
alto
term used to describe clouds of middle heights
nimbostratus
a low cloud that blankets the sky and often generates precipitation
altostratus
cloud type confined to the middle height range
cumulonimbus
clouds often associated with thunder and lightning and hail
fog 1
1. a cloud with its base at or very near the ground
fog 2
2. conditions that favor its formation are cool, clear, calm nights
fog 3
3. are at lower altitudes than clouds
precipitation
for it to form, cloud droplets must grow in volume by 1 million times
Bergeron process
process in which freezing nuclei play a role in forming precipitation
sleet 1
1. type of precipitation that consists of small clear-to-translucent ice particles
sleet 2
2. likely to occur when a layer of air with temperatures above freezing overlies a subfreezing layer near the ground