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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Troughs
upper level lows

When the height contours bend strongly to the south, (as in the diagram below), it is called a TROUGH. Strong troughs are typically preceded by stormy weather and colder air at the surface. Below is an example of a trough in an upper-level height field (red contours). The trough axis is denoted by the purple line.

[Image: trough schematic (24K)]


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 trough is located over the eastern United States and is indicated by the dip in the geopotential height field. This is the upper level extension of a surface low pressure center, which is why troughs are also called upper level lows.


Notice the relatively cold temperatures associated with the trough. This is caused by the southward transport of colder air in the lower troposphere. The trough will intensify (deepen further southward) if cold air continues to move southward at low levels in the troposphere.



geopotential height
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.

ridges