WW2010
University of Illinois

WW2010
 
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Online Guides
 
  introduction
 
> meteorology
 
  remote sensing
 
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  projects, activities

Meteorology
 
  introduction
 
  air masses, fronts
 
> clouds, precipitation
 
  el nino
 
  forces, winds
 
  hurricanes
 
  hydrologic cycle
 
  light, optics
 
  midlatitude cyclones
 
  severe storms
 
  weather forecasting

Clouds, Precipitation
 
  introduction
 
  development
 
  cloud types
 
> precipitation

Precipitation
 
  introduction
 
  rain and hail
 
> freezing rain
 
  sleet
 
  snow

Freezing Rain
 
  definition
 
  dangers
 
  regions
 
  processes
 
  conditions
 
> forecasting

Forecasting
 
  precipitation type
 
> classic sounding
 
  swrp sounding

User Interface
 
  graphics
> text

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Upper Air Soundings
useful when forecasting for freezing rain

Soundings are the most important tool for identifying potential freezing rain regimes. Three types of soundings can lead to freezing rain and the most common consists of a shallow layer of cold air at the surface with a depth of about 600 meters (1,800 feet).


Above the cold air is a layer of warmer air with a depth of about 1,400 meters (4,200 feet). Winds near the surface are usually east or southeasterly, then veer around to the southwest in the warm air, and finally become westerly in upper levels. The sounding given above represents only an average case.

[Image: warm frontal overunning (95K)]
Animation by: Hall

For precipitation to form, something is needed to force the air to rise. Warm air overrunning is the most common process in the production of freezing rain. This occurs as warm air rides up and over colder air, (as in the animation above), the water vapor condenses, producing clouds and precipitation. When the precipitation falls through an atmosphere with a temperature profile similar to the one described above, freezing rain is a likely result.



precipitation type
Terms for using data resources. CD-ROM available.
Credits and Acknowledgments for WW2010.
Department of Atmospheric Sciences (DAS) at
the University of Illinois at Urbana-Champaign.

swrp sounding