WW2010
University of Illinois

WW2010
 
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> online guides
 
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Online Guides
 
  introduction
 
> meteorology
 
  remote sensing
 
  reading maps
 
  projects, activities

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

Midlatitude Cyclones
 
  introduction
 
  definition
 
  associated winds
 
  air masses
 
  on satellite images
 
> upper air features

Upper Air Features
 
  geopotential height
 
  troughs
 
> ridges
 
  wave amplification
 
  rising motion
 
  steering level
 
  jet stream
 
  jet streaks
 
  vertical motions
 
  mid-level moisture
 
  wind vectors

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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Ridges
upper level highs

When the height contours bend strongly to the north (as in the diagram below), this is known as a RIDGE. Strong ridges are accompanied by warm and dry weather conditions at the surface. Below is an example of a ridge in an upper-level height field (red contours). The purple line denotes the ridge axis.

[Image: ridge schematic (22K)]


The image below depicts geopotential height (solid white contours) and temperatures (colored regions) at 500 mb. Temperatures decrease with color from light blue to purple. A ridge is located from Texas into Montana and is indicated by the bulge in the geopotential height field. This is the upper level extension of a surface high pressure center, which is why ridges are also called upper level highs.


Notice the relatively warm temperatures associated with the ridge. This is caused by the northward transport of warmer air in the lower troposphere. The ridge will intensify (bulge further northward) if warm air continues to move northward at low levels in the troposphere.



troughs
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.

wave amplification