WW2010
University of Illinois

WW2010
 
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Online Guides
 
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> 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

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

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Rising Motion and Surface Pressure Falls
in response to warm and cold advections

Warm and cold advection influence vertical air motion. Warm advection results in rising motion which leads to falling pressures at the surface, while cold advection leads to sinking motion, causing pressures to rise at the surface. The sequence of surface maps below show the surface pressure fields (isobars) that resulted from the warm and cold advection patterns at 850 mb.

[Image: (53K)]

The top map shows an area of low pressure over the northwestern United States and an area of high pressure over the eastern U.S. 12 hours later, there is a noticeable decrease in pressure from Texas to Illinois (region of strongest warm advection at 850 mb) while surface pressures increased in regions where the strongest 850 mb cold advection was occurring.

[Image: (49K)]

A cyclone at the surface that moves under an area of warm advection at 850mb is likely to deepen. For this reason, systems at the surface will tend to "phase lock" with systems aloft, and they will propagate more or less together.



wave amplification
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.

steering level