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A sudden, violent downdraft of air over a small area (less than 16 sq km or 6.24 sq mi) that lasts at least 25 minutes. Microbursts can cause winds with speeds as high as 270 km (167 mi) per hour. They are difficult to detect and predict with standard weather instruments. They are especially hazardous to airplanes during landing or taking off.
pattern of intense winds that descends from rain clouds, hits the ground, and fans out horizontally. Microbursts are short-lived, usually lasting from about 5 to 15 minutes, and they are relatively compact, usually affecting an area of 1 to 3 km (about 0.5 to 2 miles) in diameter. They are often but not always associated with thunderstorms or strong rains. By causing a sudden change in wind direction or speed-a condition known as wind shear-microbursts create a particular hazard for airplanes at takeoff and landing because the pilot is confronted with a rapid and unexpected shift from headwind to tailwind.