Moisture, Clouds, Precipitation PDF

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Felicia Boyd
Moisture, cloud and precipitation notes...

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Moisture, Clouds, and Precipitation Changes of State of Water 

3 states of mater – solid, liquid, gas

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Latent heat- energy transfer during the change of state without changing its temperature, stored or hidden heat o Important in atmospheric processes

Humidity    

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Humidity- amount of water vapor in the air Saturated air- air filled with water vapor to capacity o 100% relative humidity and condensation Capacity is temperature dependent – warm air has greater capacity Relative humidity- ratio of the air’s actual water vapor content compared with the amount of water vapor required for saturation at that temperature and pressure o How to change relative humidity  Add or subtract moisture to the air  Change the air temperature  Warm air can hold more moisture, so colder temperature cannot hold as many water molecules  Lowering the temperature raises the relative humidity Dew point temperature- temperature to which a parcel of air would need to be cooled to reach saturation o Cooling the air below the dew point causes condensation

Adiabatic Heating/ Cooling 

Adiabatic temperature changes when o Air expands  Rising air will expand due to decreasing air pressure  Air will cool o Air is compressed  Air will warm  Descending air is compressed due to increasing air pressure  Motion of air molecules increases

Orographic lifting 

Rain shadow effect

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Warm, moist air rises Expands (due to lower pressure) and cools adiabatically Cools to the dew point and condenses Cool air sinks Compresses and warms adiabatically Warm, dry air (desert)

Condensation and Cloud Formation 

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Things needed for cloud formation o Water vapor o Condensation nuclei o Temperature change (cooling to, at, or, below, dew point) Clouds o Cirrus- high, white, thin o Stratus- sheets or layers o Cumulus- cotton ball cloud masses o Nimbus- rain

Fog    

Fog- cloud with its base at or near the ground Advection fog- warm air, cold water Steam fog- cool air, warm water Radiation fog- warm air from earths surface is cooled by night air...