پیچاب

Also known as vortices

thumb|Vortex created by the passage of an wing|aircraft wing, revealed by colored smoke thumb|249x249px|Kármán vortex street|Von Kármán vortex street behind a drinking straw; milk was poured into the water to make the current visible thumb|right|250px|A Kármán vortex street is shown in this photo, as winds from the west blow onto clouds that have formed over the mountains in the desert. This phenomenon observed from ground level is extremely rare, as most cloud-related Kármán vortex street activity is viewed from space.