What Is A Dust Devil?

GWCC_Feed | January 29, 2019 @ 9:30 am

Dust devil formed near Mt. Bryan in South Australia.
Credit: Jacob Elliot (news.com.au)
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Although dust devils are often compared to tornadoes, a dust devil differs from a tornado because it does not form from the updraft of a supercell thunderstorm. Dust devils do form however from strong updrafts in dry convection, similar to how non-supercell tornadoes form. A dust devil is a rotating column of air that forms due to the rapid heating of a small part of the earth’s surface. Due to the difference in temperature between this warm air at the surface and the cooler air just above the surface, a shallow layer of instability is created. The convergence of these two airmasses then causes the pressure at the surface to decrease. This warm rising air pushing upwards through the cooler air above it causes circulation to develop as the warm and cool airmasses begin to rotate. This convection within the column of air can then be tilted into the vertical and further intensified by winds, causing the formation of a dust devil, as the swirling air picks up dust and dirt. Dust devils typically do not last very long, and often dissipate within minutes of their initial formation.

Large dust devil moving through the Arizona desert.
Credit: NASA/University of Michigan
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A dust devil is a whirlwind of air that becomes visible due to the type of dust, sand, soil or debris that is sucked into its rotating column of air. Dust devils are typically not dangerous. However, if severe enough, they can have a destructive impact on houses, trees, small aircrafts and other small vehicles. These severe dust devils occasionally can be strong enough to be classified as EF0 or EF1 on the Enhanced Fujita Scale for light to moderate damage. Dust devils are also much smaller in scale when compared to tornadoes, as they are usually between 3 to over 30 meters wide, and do not stretch further than 200 meters up into the sky. Dust devils most commonly occur on hot, calm days in dry regions. Although they may have strong enough winds to knock a person off balance, dust devils are not strong enough to lift a person up into the air. Steep temperature lapse rates in the lower troposphere increase the strength of the dust devil, and can potentially cause winds reaching up to 80 mph. Dust devils may have an appearance similar to tornadoes, but they are not nearly as intense.

To learn more about dust devils and other severe weather phenomena, be sure to click here!

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