WW2010
University of Illinois

WW2010
 
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Online Guides
 
  introduction
 
  meteorology
 
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> reading maps
 
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Reading Maps
 
  introduction
 
  utc conversions
 
  temp conversions
 
  surface obs
 
> surface maps
 
  upper air obs

Surafce Maps
 
  temp contours
 
  dew point reports
 
> observations, ir sat

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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Surface Obs, Isobars and Infrared Background
regional mode

[Image: sfc map: obs, isb, and infrared bgrnd (127K)]

The surface meteorological chart above depicts the current surface conditions at chosen sights across North America. This map, updated shortly after each hour, illustrates the present weather patterns and the location of storm systems over the continental United States.

The hourly observations (updated every hour) contain information about surface temperature and dew point temperature in degrees Fahrenheit, sea level pressure, wind speed and direction, cloud cover and type of weather conditions occurring at each surface station during the last hour. The hourly observations link provides detailed information on how to decode and interpret the numbers and symbols at each station. The blue contours called isobars and depict areas of High and Low pressure.

In the background, infrared satellite data shows the cloud patterns over North America. The brightness of the cloud images is inversely proportional to the temperature of cloud tops, therefore the deep clouds with high (and thus cold) cloud tops typically indicating areas of intense rain and/or hail associated with deep convection appear brightest on this image. However high cirrus clouds will often also appear very bright, but these clouds do not produce precipitation. One can attempt to relate the areas of cloudiness to the pressure pattern and the areas of precipitation depicted by the radar data (previous panel). Clouds and precipitation tend to be associated with low pressure systems also known as midlatitude cyclones.

Midlatitude cyclones can be identified as a minimum in the pressure field, and an area of cyclonic circulation of the surface flow. These storm systems are typically characterized by cloud cover in the vicinity of the low pressure center, relatively warm and moist flow with a southerly component ahead of the cold front and colder and drier airmass behind it, as well as areas of precipitation associated with both warm and cold fronts.



obs, isobars, radar
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.

temp contours