Landspout

A landspout near North Platte, Nebraska on May 22, 2004. Note the characteristic smooth, tubular shape, similar to that of a waterspout.

A landspout is a term coined by meteorologist Howard B. Bluestein in 1985 for a kind of tornado not associated with a mesocyclone. [1] The Glossary of Meteorology defines a landspout as

"Colloquial expression describing tornadoes occurring with a parent cloud in its growth stage and with its vorticity originating in the boundary layer.
The parent cloud does not contain a preexisting mid-level mesocyclone. The landspout was so named because it looks like "a weak Florida Keys waterspout over land." [2]

Landspouts form during the growth stage of a cumulus congestus cloud by stretching boundary layer vorticity upward and into the cumulus congestus's updraft. They generally are smaller and weaker than supercell tornadoes and do not form from a mesocyclone or pre-existing rotation in the cloud. Because of this, landspouts are rarely detected by Doppler weather radar. [3]

Landspouts share a strong resemblance and development process to that of waterspouts, usually taking the form of a translucent and highly laminar helical tube. Landspouts are considered tornadoes since a rotating column of air is in contact with both the surface and a cumuliform cloud. Not all landspouts are visible, and many are first sighted as debris swirling at the surface before eventually filling in with condensation and dust.

A few landspouts can persist in excess of 15 minutes and have produced F3 damage; [4] however, they rarely produce damage greater than EF-2.[ citation needed]

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Nederlands: Windhoos
português: Landspout