Plain English Meaning
The top edge of a cloud — the altitude where you would break out into clear sky if you climbed through it.
Full Definition
The upper boundary of a cloud or cloud layer, where the visible moisture ends and clear air begins above.
Context Anchor
Seen in instrument weather flying, icing reports, forecasts, and pilot reports when deciding whether climbing can get the aircraft out of clouds and icing conditions.
Why Pilots Care
Reaching the cloud tops often removes the aircraft from icing conditions, since most structural icing occurs inside the cloud layer.