12/5/2023 0 Comments Runescape images with dustA s the air rises, it cools and eventually will descend back through the center of the vortex. This increase in rotation speed from vertical stretching is similar to the increased spinning of an ice skater as they bring their arms in toward their bodies. As more hot air rushes in toward the developing vortex to replace the air that is rising, this spinning effect is intensified. This rapidly rising pocket of air may begin to rotate, and if it continues to be stretched in the vertical direction, will increase in rotation speed. The sudden uprush of hot air causes air to speed horizontally inward to the bottom of the newly-forming vortex. Once the ground heats up enough, a localized pocket of air will quickly rise through the cooler air above it. If the temperature of the ground becomes much warmer than the air above it, vertical mixing will take place to release this unstable configuration. This is a very unstable condition, since the heated air is less dense and lighter than the cooler air above it. Typically, they occur under clear skies and light winds, when the ground can warm the air to temperatures well above the temperatures just above the ground. How do Dust Devils Form?ĭust devils form in areas of strong surface heating, usually at the interface between different surface types, such as asphalt and dirt, or even irrigated fields and dirt roads. Small structures can be damaged, and even destroyed, if in the path of a strong dust devil. Even though they are generally smaller than tornadoes, dust devils can still be destructive as they lift dust and other debris into the air. Wind speeds in larger dust devils can reach 60 mph or greater. Although, in deserts typical of northern Arizona, dust devils can reach heights of several thousand feet and last on the order of an hour or more. In most locations, dust devils typically last only a few minutes before dissipating. ![]() Typical diameters of dust devils range from 10 to 300 feet, with an average height of approximately 500 to 1000 feet. These dust-filled vortices, created by strong surface heating, are generally smaller and less intense than a tornado. An example of a dust devil can be seen to the left. (Copyright: John Roenfeldt-Inflow Images)Ī common wind phenomenon that occurs throughout much of the world, including Arizona, are dust devils.
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