Dust DevilsEphemeral Whirlwinds Can Stir Up Trouble Go to Dust Devils sections: Dust devils are a common weather phenomenon in Arizona. You can see them as you look out over the dusty tan and green scrub while driving across the desert. They look like a wispy brown twister, swirling across the wide open flats, kicking up dust, twigs and leaves to all sides. These swirling columns of air form on hot, sunny days with light winds in areas where there is strong surface heating. The temperature only has to get to above 80 degrees Fahrenheit for one to begin. How Do Dust Devils Form?There’s a lot of physics involved in the creation of dust devils.
In layman’s terms, they form when a warm column of air rising over bare soil or asphalt "bumps" into the cooler, sinking air of vegetation. The sharp temperature differential creates a vortex of air circulation that begins to rise. A gust of wind - or even some swirling air caused by variations in the terrain - then pushes this horizontal air mass onto its side, creating a vertical mass of air circulation, spinning like a top. The sudden uprush of hot air causes surrounding air to rush horizontally inward to the bottom of the newly forming vortex. Soon, much of the surrounding air is sucked in, intensifying the upward spiraling of the vortex. This rising air continues to rotate. As this mass begins to move across the ground, it picks up dust, making the spinning vortex visible to the eye. A dust devil will continue its haphazard path across the land until the air temperature diminishes and the air circulation loses momentum, thus collapsing the vortex. Dust Devil FactsContrary to popular belief, they are are not mini-tornadoes because they are not associated with severe thunderstorms.Generally these dusty whirlwinds are less than 3 feet in diameter and 500 - 1,000 feet high with winds of about 45 miles per hour. Most last for less than a minute, which can make trying to photograph them a real challenge! However, some have been reported to tower in the sky for more than 20 minutes, traveling at speeds of up to 75 miles per hour and getting as big as 100 yards wide!
Though most cause no damage, they can knock out power and blow over anything not fastened down. Some have even blown the roofs off of small buildings. Although dust devils can form anywhere in Arizona, they are most commonly seen in open desert areas and farmlands. Look for them in the boundaries between irrigated farm fields and dry, sparsely vegetated desert or dirt roadways. We most frequently see them in:
However, they do occur in forested areas. A very large dust devil hit the Coconino County Fairgrounds in northern Arizona on September 14, 2000, knocking over tents, splitting the wood beams of one pavilion and causing numerous injuries from flying debris. Dust Devil SafetyWorking outside in summer, we frequently witnessed the power of dust devils.
Even when a small one – only a few feet in diameter - hit us, it felt like being sprayed with buckshot. If you see one coming, especially if it's large, get out of its way. Quickly get into the nearest building or vehicle. If no shelter is available and you can’t get out of the way, turn your back into it, so you can avoid being hit in the face with flying debris and dirt. This, however, is your last best option. You really do want to get out of the way of dust devils as the flying debris that they carry can cause black eyes and even broken bones. Sources: National Weather Service, NASA, UC Berkeley Department of Physics Note to the Reader: This page is intended for informational purposes only. It is not a substitute for professional advice. This information is not meant to cover every possible scenario or outcome. Before you travel, do your homework. YOU are solely responsible for your personal safety. Road conditions, weather and your personal knowledge and abilities all vary considerably. We cannot assume responsibility for you or anyone else’s safety that reads and uses this information. Safety really comes down to common sense and being aware of your abilities and limitations. Always inquire locally before traveling. Always be conservative when planning your trips and routes. Return to Arizona Weather page from Dust Devils page
Legal Disclaimer: Arizona-Vacation-Planner.com accepts no responsibility for any loss, injury or inconvenience sustained by anyone resulting from this information.
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