Definition
A visible mass of tiny water droplets, ice crystals, or both, suspended in the atmosphere above the Earth's surface. Clouds form when air is cooled to its dew point and water vapor condenses onto microscopic particles in the air.
Plain English
The visible white or grey shapes you see in the sky, made of countless tiny water droplets or ice crystals floating together in the air.
Context Anchor
Pilots encounter this term in weather reports, forecasts, preflight planning, and in flight when judging visibility and cloud clearance.
Derivation
From Old English 'clud,' originally meaning a mass of rock or hill. The word was later applied to rain clouds because of their similar lumpy, mounded appearance in the sky. The shift from rock to sky-mass happened in Middle English.
Why Pilots Care
Clouds determine visibility, ceilings, possible icing, and whether visual flight is allowed or instrument procedures are required.
Grounding Statement
When invisible water vapor cools enough, tiny droplets or ice crystals can form and become visible as a cloud.
Intuition Check
A cloud is not just a harmless white shape in the sky. In aviation, a cloud is a weather feature that can limit what a pilot can see and change what rules or precautions apply.
Example Sentence 1
The pilot climbed to 9,500 feet to stay above a layer of clouds that was building over the mountains.
Example Sentence 2
We climbed above the cloud layer to maintain visual contact with the ground.