What defines windshear?

Windshear is specifically defined as a sudden change in wind velocity and/or direction over a short distance. This phenomenon can occur vertically or horizontally and is critical in aviation because it can create unexpected and hazardous conditions for aircraft, especially during takeoff and landing.

Understanding windshear is essential for pilots, as it can lead to significant changes in airspeed and lift, which are vital for maintaining control of the aircraft. Unlike gradual changes in wind speed or direction, which might not impact flight as dramatically, windshear can occur very quickly and can be difficult to predict, making it a key focus for safety in flight operations.

The other options refer to more uniform or less dramatic wind changes that do not capture the sudden and potentially dangerous nature of windshear. For instance, a gradual change in wind speed or a steady wind change over time might not pose the same risks as the abrupt shifts characteristic of windshear.