Types of Tornadoes

A multiple-vortex tornado outside of Dallas, Texas on April 2, 1957.

True tornadoes

Multiple vortex tornado
A multiple vortex tornado is a type of tornado in which two or more columns of spinning air rotate around a common center. Multivortex structure can occur in almost any circulation, but is very often observed in intense tornadoes.

Satellite tornado
A satellite tornado is a term for a weaker tornado which forms very near a large, strong tornado contained within the same mesocyclone. The satellite tornado may appear to "orbit" the larger tornado (hence the name), giving the appearance of one, large multi-vortex tornado. However, a satellite tornado is a distinct funnel, and is much smaller than the main funnel.[3]

A waterspout near the Florida Keys.
A waterspout near the Florida Keys.

Waterspout
A waterspout is officially defined by the US National Weather Service simply as a tornado over water. However, researchers typically distinguish "fair weather" waterspouts from tornadic waterspouts.

* Fair weather waterspouts are less severe but far more common, and are similar in dynamics to dust devils and landspouts.[13] They form at the bases of cumulus congestus cloud towers in tropical and semitropical waters.[13] They have relatively weak winds, smooth laminar walls, and typically travel very slowly, if at all.[13] They occur most commonly in the Florida Keys.[14]
* Tornadic waterspouts are more literally "tornadoes over water". They can form over water like mesocyclonic tornadoes, or be a land tornado which crosses onto water. Since they form from severe thunderstorms and can be far more intense, faster, and longer-lived than fair weather waterspouts, they are considered far more dangerous.

A landspout near North Platte, Nebraska on May 22, 2004.
A landspout near North Platte, Nebraska on May 22, 2004.

Landspout
Landspout is an unofficial term for a tornado not associated with a mesocyclone. The name stems from their characterization as essentially a "fair weather waterspout on land". Waterspouts and landspouts share many defining characteristics, including relative weakness, short lifespan, and a small, smooth condensation funnel which often does not reach the ground. Landspouts also create a distinctively laminar cloud of dust when they make contact with the ground, due to their differing mechanics from true mesoform tornadoes. Though usually weaker than classic tornadoes, they still produce strong winds and may cause serious damage.[3][15]

Tornado-like circulations

Gustnado
A gustnado (gust front tornado) is a small, vertical swirl associated with a gust front or downburst. Because they are technically not associated with the cloud base, there is some debate as to whether or not gustnadoes are actually tornadoes. They are formed when fast moving cold, dry outflow air from a thunderstorm is blown through a mass of stationary, warm, moist air near the outflow boundary, resulting in a "rolling" effect (often exemplified through a roll cloud). If low level wind shear is strong enough, the rotation can be turned horizontally (or diagonally) and make contact with the ground. The result is a gustnado.[3][16] They usually cause small areas of heavier rotational wind damage among areas of straight-line wind damage. It is also worth noting that since they are absent of any Coriolis influence from a mesocyclone, they seem to be alternately cyclonic and anticyclonic without preference.

Dust devil in Johnsonville, South Carolina.
Dust devil in Johnsonville, South Carolina.

Dust devil
A dust devil resembles a tornado in that it is a vertical swirling column of air. However, they form under clear skies and are rarely as strong as even the weakest tornadoes. They form when a strong convective updraft is formed near the ground on a hot day. If there is enough low level wind shear, the column of hot, rising air can develop a small cyclonic motion that can be seen near the ground. They are not considered tornadoes because they form during fair weather and are not associated with any actual cloud. However, they can, on occasion, result in major damage, especially in arid areas.[17][18]

Winter Waterspout
A winter waterspout, also known as a snow devil, an icespout, an ice devil or a snowspout, is an extremely rare meteorological phenomenon in which a vortex resembling that of a waterspout forms under the base of a snow squall.

Fire whirl
Tornado-like circulations occasionally occur near large, intense wildfires and are called fire whirls. They are not considered tornadoes except in the rare case where they connect to a pyrocumulus or other cumuliform cloud above. Fire whirls usually are not as strong as tornadoes associated with thunderstorms. However, they can produce significant damage.[8]

Cold air vortex
A cold air vortex or shear funnel is a tiny, harmless funnel cloud which occasionally forms underneath or on the sides of normal cumuliform clouds, rarely causing any winds at ground-level.[19] Their genesis and mechanics are poorly understood, as they are quite rare, short lived, and hard to spot (due to their non-rotational nature and small size).
Extracted from Wikipedia