Dust Devils

When there is a steep lapse rate near the ground, thermals will release aggressively, and the air rushing in to fill the area below it can create a strong rotation called a ‘Dust Devil’. The presence of Dust Devils can indicate strong or extremely unstable conditions. They can also be present when there are opposing forces, such as wind pushing against the anabatic (thermal) flow direction. Dust devils are extremely turbulent and should be avoided. If there are dust devils occurring at a launch, and you decide to fly, exercise great caution and maintain terrain clearance. These are not appropriate conditions to be scratching for lift at low altitudes or close to the terrain. If you are flying a site with light, powdery dust, the dust devils can be used to locate strong thermals. If you choose to utilize these strong thermals, you should only enter them above 1000 ft off the ground, at 500 ft above the top of the visible dust, and opposite their direction of turn, so you enter with a headwind. Many good thermal and cross country sites will have dust devils. Often they are not visible if there are no light materials to be lofted.