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What are dustdevils?
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| A dustdevil is a whirlwind into which dust and debris gets caught up, making it visible. Dust devils form
through a different mechanism than tornadoes, and are much smaller, usually only 10 to 50 feet in diameter, and usually not
extending more than 100 feet into the air. They usually are seen in relatively dry conditions,
when sunlight is providing strong heating of the surface, and when winds are generally light. The heated land surface
can start to produce convective rolls of air (as in the diagram above). Some of these rolls can get tilted upright,
producing a dust devil.
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| Interesting facts:
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DUST DEVILS EVERYWHERE!: After the eruption of Mt. St. Helens
in Washinton state in 1980, there
was a layer of white volcanic ash deposited over thousands of square miles of land. Literally hundreds
of dust devils could be observed in a single day during sunny conditions, as numerous whirlwinds picked
up the light, very visible ash, forming dust devils. It is likely that there are many more of these than people
see, since they only become visible when they pick up debris or soil.
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