The Arizona Republic

Dust devil name origin is as murky as the ‘devil’ itself

- The Best of Clay Thompson

From June 21, 2006:

Today’s question:

Recently I saw a dust devil towering into the sky up to about 500 feet. How did these devils get their names and how do they get started?

How did dust devils get their name? I don’t know. I’m not sure anybody knows.

I do know the phrase came into use around 1830. I guess it refers to the fact dust devils just seem to pop up out of nowhere and look kind of fierce and whirl around and then disappear.

Do you know who Lilith is? In some Jewish traditions she was Adam’s first wife. It’s a long story, but she became a demon. She also turns up in ancient Sumerian stories as a demon who lived in a tree, and in Sumerian her name meant “devil wind” or “demon wind.” It’s not known if that referred to just a dust devil or a really destructiv­e wind.

Dust devils are born when sunlight heats the surface of the ground so it is a lot hotter than the air just above it. So the lighter, less-dense air starts to rise. The heating of a surface by the sun’s rays is called insolation, by the way.

Anyway, rising hot air causes more air to flow in horizontal­ly, and that causes the rising warm air to rotate with a counterclo­ckwise spin. And as the dust devil grows in height, the rotation gets faster, like an ice skater pulling in her arms to spin faster.

Meanwhile, as the air rises, it starts to cool and backs down through the vortex. More hot air is pulled in and rises along the outside of the spinning column, and the whole dusty whirlwind scoots along the ground until it runs out of the hot, unstable air that fuels it. Some of them come and go just like that, and some can go on for several minutes.

You tend to see a lot of dust devils over flat areas where there isn’t as much frictional drag to slow down hot air pushing into the vortex.

Dust devils can hit speeds of about 50 mph, although in September 2000, one smacked around the Coconino County Fairground­s with winds estimated at 75 mph.

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