What Causes Dust Devils Anyhow?

By Chris Martz

Earlier today, a rotating column of dust formed over a football field at Brooks Junior High School in Alberta, Canada.

These upward whirlwind, dusty, debris-filled vortexes of air are generally referred to as “dust devils,” although they are sometimes called “willy willys.”¹ ² ³ ⁴ Dust devils are generally formed in desert or dry areas and resemble tornadoes, however they are much shorter in height, ranging from 100 to 1,000 feet in height, and only 10 to 50 feet in diameter.² ⁴

diagram of how a dust devil forms
Dust-devil formation⁴ – WeatherQuestions.com

While tornadoes grow downward from funnel clouds in the sky, dust devils grow upwards from the ground due to irregularities near the surface.² ⁴ A heated surface allows convective rolls of air to form because the wind speed increases with altitude.² ⁴ When these convective rolls get tilted upward, then the warm air runs into cooler air aloft creating a rotating vortex of air, which often reaches speeds of 20 to 30 miles per hour, although they can reach higher speeds.⁴

Dust devils, like tornadoes will only last a few minutes. Once cooler air gets drawn into the base of the vortex, that cuts off the heat supply, ending the rotation.⁴

REFERENCES

[1] Other Weather Types (National Weather Service JetStream)
https://www.weather.gov/jetstream/othertypes Accessed 15 Apr. 2019.

[2] Willy-willy (Met Office)
https://www.metoffice.gov.uk/weather/learn-about/weather/types-of-weather/wind/willy-willy Accessed 15 Apr. 2019.

[3] Skilling, Tom, Dust devils-atmospheric whirlwinds that resemble small tornadoes (WGN-TV | Chicago’s Very Own source for breaking news, weather, sports and entertainment, 12 May 2018)
https://wgntv.com/2018/05/12/dust-devils-atmospheric-whirlwinds-that-resemble-small-tornadoes/ Accessed 15 Apr. 2019.

[4] Dr. Roy Spencer, Ph.D. What causes dust devils? (WeatherQuestions.com, 11 Jan. 2011)
http://weatherstreet.com/weatherquestions/What_are_dust_devils.htm Accessed 15 Apr. 2019.

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