A dust devil is a strong, well-formed, and relatively long-lived whirlwind, ranging from small (half a meter wide and a few meters tall) to large (more than 10 meters wide and more than 1000 meters tall). The primary vertical motion is upward. Dust devils are usually harmless, but rare ones can grow large enough to threaten both people and property.
They are comparable to tornadoes in that both are a weather phenomenon of a vertically oriented rotating column of air. Most tornadoes are associated with a larger parent circulation, the mesocyclone on the back of a supercell thunderstorm. Dust devils form as a swirling updraft under sunny conditions during fair weather, rarely coming close to the intensity of a tornado.
In the southwestern United States, a dust devil is sometimes called a "dancing devil" or a "sun devil". In Death Valley, California, it may be called a "sand auger" or a "dust whirl".
The Navajo refer to them as chiindii, ghosts or spirits of dead Navajos. If a chindi spins clockwise, it is said to be a good spirit; if it spins counterclockwise, it is said to be a bad spirit.
The Australian English term "willy-willy" or "whirly-whirly" is thought to derive from Yindjibarndi or a neighboring language. In Aboriginal myths, willy willies represent spirit forms. They are often quite scary spirits, and parents may warn their children that if they misbehave, a spirit will emerge from the spinning vortex of dirt and chastise them. There is a story of the origin of the brolga in which a bad spirit descends from the sky and captures the young being and abducts her by taking the form of a willy-willy.
In Saudi Arabia, Kuwait, Iran, Kazakhstan, and Jordan, they often reach hundreds of meters in height and are referred to as djin ("genies" or "devils").
Egypt has its fasset el 'afreet, or "ghost's wind".
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