February - halos You are here: Home Photo gallery Miscellaneous Weather effects on soil Dust devils

A dust devil is a spinning vortex of air that starts at the ground due to strong differential heating of the surface by the sun. The vortex is triggered by a quickly rising thermal near the ground; the vorticity in the air makes the air inflow spiral to the low pressure under the thermal, concentrating into a vortex. The fast spinning air may kick up dust or grass, making the vortex visible, and sometimes even intensifying the vortex due to increased absorption of sunlight.

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Observing tips

Most dust devils last only a few minutes at most, traveling with the wind. Dust devils most frequently occur in the spring and early summer around noon local time, when the ambient air is not too warm, but the sun is irradiating the soil strongly. As soon as the vortex forms, it will kick up dust and usually dissipate in a few seconds.

If you want to photograph a dust devil, you have to be either very fast, or very lucky. Look for a dusty area - a plowed dirt field or desert is very suitable. There may be wind, but the wind should not be too strong, and little wind is better for dust devils to form.