WW2010
University of Illinois

WW2010
 
  welcome
 
> online guides
 
  archives
 
  educational cd-rom
 
  current weather
 
  about ww2010
 
  index

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

Severe Storms
 
  introduction
 
  dangers of t-storms
 
  types of t-storms
 
> tstorm components
 
  tornadoes
 
  modeling

Tstorm Components
 
  introduction
 
  updrafts/downdrafts
 
  wind shear
 
  outflow phenomena
 
> wall clouds

Wall Clouds
 
  introduction
 
> beneath cb towers
 
  short-lived
 
  cyclic wall clouds
 
  with rotation

User Interface
 
  graphics
> text

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Wall Clouds Beneath CB Towers
visual clues of storm potential

Here we have a southward view of a supercell, with precipitation in the right middle-ground and a wall cloud beneath the cumulonimbus (Cb) tower and anvil overhang in the background. The wall cloud produced a tornado within 30 minutes in southwest Oklahoma City.

[Image: wall cloud from distance of five miles (62K)]
Photograph by: Doswell

Looking west from 5 miles away, note the supercell wall cloud. We have learned much about the nature of wall clouds in the last decade. For instance, persistent wall clouds signify a strong updraft which is capable of producing large hail, and if conditions are right, tornadoes. However, only a few cloud-base lowerings actually are wall clouds, and probably less than half of all legitimate wall clouds spawn tornadoes.

[Image: wall cloud in advance of severe storm (51K)]
Photograph by: Doswell

This is not to minimize the importance of wall clouds, as they are a reasonable indicator of updraft strength. The most visually-impressive examples characteristically precede the most powerful tornadoes. This ominously dark wall cloud occurred with a very severe hailstorm and several weak tornadoes.



introduction
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Credits and Acknowledgments for WW2010.
Department of Atmospheric Sciences (DAS) at
the University of Illinois at Urbana-Champaign.

short-lived