Definition
Moisture from the air that condenses as small water droplets on a surface when that surface cools to a temperature at or below the dew point of the surrounding air, while still above freezing.
Plain English
Tiny water droplets that form on a cool surface when the air touching it gets cold enough for its moisture to turn from vapor into liquid.
Context Anchor
Pilots most often notice dew during a morning walk-around after an aircraft has been parked outside overnight.
Derivation
From Old English 'deaw,' meaning moisture or water that settles in small drops. The everyday word and the aviation usage are the same idea — what changes is why the pilot cares about it.
Why Pilots Care
Dew on aircraft surfaces reduces lift and must be removed before flight; its presence also indicates conditions that can lead to fog or frost.
Analogy
Think of a cold drink glass on a warm day — the droplets that appear on the outside are dew. The glass cooled the air around it enough for moisture to condense out.
Grounding Statement
On a cool, calm morning, an aircraft skin can become cool enough that invisible moisture in the air turns into visible drops on the airplane.
Intuition Check
Dew is not rain. It forms on a cool surface from moisture already in the air around that surface.
Example Sentence 1
During the preflight walk-around, the pilot noticed dew on the wings and wiped it away before checking the fuel vents.
Example Sentence 2
Clear skies and light winds overnight allowed dew to form on the parked aircraft.