WW2010
University of Illinois

WW2010
 
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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

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

Types of T-storms
 
  storm spectrum
 
  single cell storms
 
  multicell clusters
 
  multicell lines
 
> supercells

Supercells
 
  introduction
 
  on radar
 
> schematic diagrams
 
  features
 
  variations
 
  hp supercells
 
  lp supercells
 
  multicell to supercell
 
  tornadic supercell

User Interface
 
  graphics
> text

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Schematic Diagrams
horizontal cross-section and westward view

This is a horizontal, low-level cross-section of a "classic" supercell. The storm is characterized by a large precipitation area on radar, and a pendant or hook-shaped echo wrapping cyclonically around the updraft area. Note the position of the updraft and the gust front wave. The intense updraft suspends precipitation particles above it, with rain and hail eventually blown off of the updraft summit and downwind by the strong winds aloft. Updraft rotation results in the gust front wave, with warm surface air supplying a continual feed of moisture to the storm.

[Image: horizontal low-level cross-section of a classic supercell (54K)]

Updraft rotation occurs when winds through the troposphere are moderate to strong, and low-level turning is significant. As inflow air in the lowest 1-3 kilometers approaches the storm from the south or southwest, the low level turning results in the development of rotation about a horizontal axis. As the air is lifted into the updraft, the rotation is "tilted" to that about a vertical axis. To see this rotation about a horizontal axis caused by wind shear, imagine rolling a tube along a table-top with the palm of your hand.

The movement of your hand represents the strong winds above the surface, producing rotation because the winds near the ground are much weaker. This simple picture is complicated by the turning of the wind direction with height, but the concept remains similar. Lifting this "horizontal" vortex into the updraft results in cyclonic rotation.

A westward view of the classic supercell reveals the wall cloud beneath the intense updraft core and an inflow tail cloud on the rainy downdraft side of the wall cloud. Wall clouds tend to develop beneath the north side of the supercell rain-free base, although other configurations occur.

[Image: schematic of a classic supercell (63K)]

Observe the nearly vertical, "vaulted" appearance of the cloud boundary on the north side of the Cb and adjacent to the visible precipitation area. A sharp demarcation between downdraft and rotating updraft results in this appearance. Note the anvil overhang on the upwind (southwest) side of the storm and the overshooting top, both visual clues as to the intensity of the updraft.



on 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.

Features