Changes

[[File:lighterstill.jpg]][[File:Whirlwinds.jpg|right|frame]]

[[File:lighterstill.jpg]][[File:Whirlwinds.jpg|right|frame]]

*[http://en.wikipedia.org/wiki/14th_century 14th Century]

*[https://en.wikipedia.org/wiki/14th_century 14th Century]

==Definitions==

==Definitions==

*1: a small rotating windstorm of limited extent

*1: a small rotating windstorm of limited extent

A '''whirlwind''' is a [[weather]] [[phenomenon]] in which a [[vortex]] of [[wind]] (a vertically oriented rotating column of air) forms due to instabilities and [[turbulence]] created by [[heating]] and [[flow]] (current) gradients. Whirlwinds occur all over the world and in any [[season]].

A '''whirlwind''' is a [[weather]] [[phenomenon]] in which a [[vortex]] of [[wind]] (a vertically oriented rotating column of air) forms due to instabilities and [[turbulence]] created by [[heating]] and [[flow]] (current) gradients. Whirlwinds occur all over the world and in any [[season]].

Whirlwinds are subdivided into two main [[types]], the great (or major) whirlwinds and the lesser (or minor) whirlwinds. The first category includes [http://en.wikipedia.org/wiki/Tornado tornadoes], [http://en.wikipedia.org/wiki/Waterspout waterspouts], and [http://en.wikipedia.org/wiki/Landspout landspouts]. The range of atmospheric vortices constitute a [[continuum]] and are difficult to categorize definitively. Some lesser whirlwinds may sometimes form in a similar [[manner]] to greater whirlwinds with related increase in [[intensity]]. These intermediate types include the [http://en.wikipedia.org/wiki/Gustnado gustnado] and the [http://en.wikipedia.org/wiki/Fire_whirl fire whirl]. Other lesser whirlwinds include [http://en.wikipedia.org/wiki/Dust_devil dust devils], as well as steam devils, snow devils, debris devils, leaf devils, and shear eddies such as the mountainado and eddy whirlwinds.

Whirlwinds are subdivided into two main [[types]], the great (or major) whirlwinds and the lesser (or minor) whirlwinds. The first category includes [https://en.wikipedia.org/wiki/Tornado tornadoes], [https://en.wikipedia.org/wiki/Waterspout waterspouts], and [https://en.wikipedia.org/wiki/Landspout landspouts]. The range of atmospheric vortices constitute a [[continuum]] and are difficult to categorize definitively. Some lesser whirlwinds may sometimes form in a similar [[manner]] to greater whirlwinds with related increase in [[intensity]]. These intermediate types include the [https://en.wikipedia.org/wiki/Gustnado gustnado] and the [https://en.wikipedia.org/wiki/Fire_whirl fire whirl]. Other lesser whirlwinds include [https://en.wikipedia.org/wiki/Dust_devil dust devils], as well as steam devils, snow devils, debris devils, leaf devils, and shear eddies such as the mountainado and eddy whirlwinds.

Major whirlwinds last longer because they are formed from very [[powerful]] [[winds]], and it is hard, though not impossible, to interrupt them. Minor whirlwinds are not as long-lived; the winds that form them do not last long, and when a minor whirlwind encounters an obstruction (a building, a house, a tree, etc.), its [[rotation]] is interrupted, as is the windflow into it, causing it to [[dissipate]].[http://en.wikipedia.org/wiki/Whirlwind]

Major whirlwinds last longer because they are formed from very [[powerful]] [[winds]], and it is hard, though not impossible, to interrupt them. Minor whirlwinds are not as long-lived; the winds that form them do not last long, and when a minor whirlwind encounters an obstruction (a building, a house, a tree, etc.), its [[rotation]] is interrupted, as is the windflow into it, causing it to [[dissipate]].[https://en.wikipedia.org/wiki/Whirlwind]

[[Category: General Reference]]

[[Category: General Reference]]