Definition
Any form of water particle, liquid or solid, that is suspended in the atmosphere or falling through it. Hydrometeors include rain, drizzle, snow, sleet, hail, fog, mist, dew, frost, and clouds.
Plain English
A general weather term for any water in the air, whether it is floating around as droplets or ice crystals or falling to the ground as rain, snow, or hail.
Context Anchor
Seen in aviation weather and meteorology discussions when grouping rain, fog, snow, hail, frost, and similar water or ice conditions.
Derivation
From the Greek 'hydro' meaning water, plus 'meteor,' which originally meant 'thing in the air' (not the space rocks we think of today). So a hydrometeor is literally a 'water thing in the air.' The space-rock meaning of meteor came later; the older meaning still survives in weather science.
Why Pilots Care
Hydrometeors reduce visibility, create icing hazards, and affect takeoff, landing, and flight safety decisions.
Grounding Statement
If the weather feature is made of water or ice, such as fog ahead of the airplane or frost on the wing, it is a hydrometeor.
Intuition Check
Do not read “meteor” here as a rock from space. In hydrometeor, “meteor” means a weather thing in the air, and “hydro” tells you it is water-based.
Example Sentence 1
Fog, rain, and snow are all classified as hydrometeors in aviation weather reports.
Example Sentence 2
Hail as a hydrometeor can damage the windshield and requires avoiding the storm cell.