Wall cloud
Encyclopedia : W : WA : WAL : Wall cloud
A wall cloud is a cloud formation. It is a lowering beneath the rain-free portion of a thunderstorm, and indicates the area of maximum updraft. In the special case of a supercell thunderstorm, the wall cloud will often be seen to be rotating. It is the area of the thunderstorm which is most likely to produce tornadoes.
They can extend from a being a fraction of a mile wide to over five miles across, and typically form at the south or southwest end of a supercell mesocyclone.
Occasionally people see a shelf cloud and think they have seen a wall cloud, which is an easy mistake, since an approaching shelf cloud appears to form a wall made of cloud. Generally speaking, a shelf cloud appears on the leading edge of a storm, and a wall cloud will usually be at the rear of the storm.
External links
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.