Definition
The upper boundary of a cloud or cloud layer, where the visible moisture ends and clear air begins above.
Plain English
The top edge of a cloud — the altitude where you would break out into clear sky if you climbed through it.
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.
Intuition Check
Do not think of cloud tops as a solid roof or a perfectly flat level. They are the uneven upper edge of a cloud layer, and their altitude can change from place to place.
Example Sentence 1
The PIREP reported cloud tops at 9,000 feet, so the pilot planned to cruise at 11,000 to stay clear of icing conditions.
Example Sentence 2
Forecast cloud tops at 10,000 feet allowed the flight to top the layer in clear air.