Plain English Meaning

Bumpy, rough air that hits without warning in a clear sky. Nothing on the windscreen or radar tells you it is coming — the aircraft just suddenly shakes or jolts.

Full Definition

Sudden, sharp turbulence that occurs in cloudless air, typically at high altitudes near the jet stream where fast-moving air shears against slower-moving air. Because there are no clouds or visible weather, it cannot be seen and is rarely detected by onboard weather radar.

Context Anchor

Seen in weather briefings, pilot reports, and high-altitude flight planning, especially near or jet stream .