Wiktionary
n. A kind of tornado not associated with the mesocyclone of a thunderstorm.
Wikipedia
A landspout is a term coined by meteorologist Howard B. Bluestein in 1985 for a kind of tornado not associated with the mesocyclone of a thunderstorm. 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 midlevel mesocyclone. The landspout was so named because it looks like "a weak Florida Keys waterspout over land."Landspouts form during the growth stage of convective clouds by stretching boundary layer vorticity upward and into the cumuliform tower's updraft. They generally are smaller and weaker than supercellular tornadoes and do not contain a mesocyclone or pre-existing rotation in the cloud. Because of this, landspouts are rarely detected by Doppler weather radar.
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. Landspouts are most common in semi-arid climates characterized by high cloud bases and considerable low-level instability. These conditions tend to favor the High Plains of the United States from Spring through Summer.
A few landspouts can persist in excess of 15 minutes and have produced F3 damage; however, most of them rarely produce damage given their abbreviated duration, typical slow forward motion, and compact wind field. The potential for damage is further minimized over sparsely populated regions such as the High Plains.
Usage examples of "landspout".
Back to the time when purple landspouts raged the high plains, back to the time when boulders fell like rain, and when the devil kids were the only beings who dared to run the hillocks outside the shambletowns.
Nor did the purple furies of the landspouts usually penetrate into the hills and gullies.
When I was not dodging the landspouts, or the ice rains, or the rivers of death, I was dodging the shambletowners and their slings.
The Denv ruins were one of the few clusters left on the Noram continent, protected from the worst of the landspouts by the natural depression in which the old city had been built, and by the closeness of the foothills and the mountains behind.
Not quite dark enough for a landspout, but the wind velocity would continue to rise and the temperature to drop.
Under the stone jumble, this time Gerswin thought he could detect a squarish pattern of sorts, although when he had first surveyed Washton, he had found it difficult tQ match the tapes with the devastation that time and thy landspouts had wrought.
The landspouts had scoured everything clean except the foundation outlines and dumped the stone and iron into a twisted heap at the eastern end of the unnaturally flattened hilltop.
Sides, don't want to end up scrapped by the landspouts," observed the pilot as he began the rotor retraction sequence.
He has already requested a flitter to survey a landspout and tasked Lieutenant Deran as his co-pilot.
From his dress, the man was a retired tech, one of the few who had elected to remain once their obligations had expired, despite the landspouts and the cold.
The landspouts were less frequent in the reclaimed areas around the base.
But he ran, stretching out his strides into the effortless and ground-covering lope of a devilkid ahead of the she-coyotes, racing the landspouts and the terrors of Old Earth.