Q&A: Dust Devils

Question:  How far can a dust devil travel before it runs out of steam? I’ve seen some last pretty long out here in the open desert near my house. — PS, Cave Creek, AZ

Answer: Dust Devils rely on hot air near the ground to feed the rising vortex. They can persist for anywhere from a few seconds to an hour, depending on the amount of heat available. I’ve personally observed several in the 10-15 minute range. After these large ones burn out, they often leave huge clouds of dust and debris floating in the air for up to an hour, depending on winds. On one occasion, I saw an umbrella tent carried aloft.

How far they can travel is another question. Sometimes they are more or less stationary and don’t really go anywhere. Sometimes they just wander around in circles. Dust devils rarely travel in a straight line, but when they do they can track, on average, for up to a mile.

Topography is a significant factor as well. In large open areas,  it’s easier for fresh hot air to flow in and continue feeding them. In areas that are hilly or heavily vegetated, they’ll burn out  much  more  quickly. Interestingly, we have seen dust devils on Mars too. With no vegetation to interfere, they can persist much longer. Often, they’ll leave tracks visible as streaks on the surface, some of which are 15 miles long!

The video below shows  large dust devil in the Mojave Desert of California. Give it some time to load, as the file size is 1.4 MB. Then just click on the screen to play it.

 
 
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