WW2010
University of Illinois

WW2010
 
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Online Guides
 
  introduction
 
> meteorology
 
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Meteorology
 
  introduction
 
> air masses, fronts
 
  clouds, precipitation
 
  el nino
 
  forces, winds
 
  hurricanes
 
  hydrologic cycle
 
  light, optics
 
  midlatitude cyclones
 
  severe storms
 
  weather forecasting

Air Masses, Fronts
 
  introduction
 
  air masses
 
> fronts
 
  advection

Fronts
 
  introduction
 
  stationary front
 
> cold front
 
  warm front
 
  occluded front
 
  dry line

Cold Front
 
  definition
 
> wind shift
 
  lower dew points
 
  cyclones
 
  precipitation

User Interface
 
  graphics
> text

NOTE: We've guessed that you're not using a client that supports colored tables and have tried to compensate. Low graphics mode looks much better on clients that do... we recommend switching to Netscape 3.0 or Microsoft Internet Explorer.
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Finding Cold Fronts Using Wind Direction
shift from south-southwest to west-northwest

Cold fronts are not always identifiable by simply examining the temperature field alone. Other fields must also be taken into consideration. For example, below is a surface weather map with an analyzed low pressure center (red "L") and associated cold front (blue line) and warm front (red line). The numbers are surface temperature reports and the symbols are wind barbs, indicating wind direction and wind speed.

At the time this map was generated, temperatures ahead of the cold front were in the 50's, while behind the front, temperatures were only slightly colder (in the 40's and 50's). However, notice the change in wind direction (as indicated by the wind barbs) from one side of the cold front to the other. Winds ahead of the cold front were generally from south-southwest, while behind the front, winds had shifted around and were blowing out of the west. This sudden shift in wind direction was the key indicator that a cold front was present.

A sudden change in wind direction is commonly observed with the passage of a cold front. Before the front arrives, winds ahead of the front (in the warmer air mass) are typically out of the south-southwest, but once the front passes through, winds usually shift around to the west-northwest (in the colder air mass).



definition
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.

lower dew points