Plain English Meaning

Wind shear is when the wind suddenly changes speed or direction over a small distance, so the air your aircraft is flying through behaves very differently from the air it was flying through a moment before.

Full Definition

A change in wind speed or wind direction over a short distance in the atmosphere. Wind shear can occur in any direction — horizontally, vertically, or both — and may be encountered at any altitude. It is most hazardous near the ground, where rapid changes in airspeed or lift can occur faster than the pilot can correct for them.

Context Anchor

Pilots encounter wind shear in weather reports, tower or controller alerts, onboard warnings, and during or when the ’s airspeed or changes unexpectedly.