Definition
Ice pellets are a form of precipitation consisting of small, transparent or translucent grains of ice, generally less than 5 mm in diameter, that form when raindrops fall through a layer of below-freezing air and freeze before reaching the ground. Their presence indicates a temperature inversion with warmer air aloft over a colder layer near the surface, and signals the likelihood of freezing rain at higher altitudes.
Plain English
Small frozen raindrops that bounce when they hit the ground. They form when rain falls through a cold layer of air close to the surface and freezes on the way down.
Context Anchor
Seen in aviation weather reports, forecasts, and preflight weather briefings when winter weather may affect a flight.
Derivation
“Ice” comes from Old English for frozen water. “Pellet” comes from an old French word meaning a small ball. Together, the words point to the practical meaning: small balls or bits of frozen water falling as weather.
Why Pilots Care
Signals a temperature inversion with freezing rain above, creating a high risk of rapid airframe icing.
Grounding Statement
Picture raindrops falling into a cold layer of air near the ground and turning into tiny ice balls before they land.
Intuition Check
Ice pellets are not the same as hail. Hail forms in thunderstorms; ice pellets usually form when falling water freezes again in cold air before reaching the ground.
Example Sentence 1
The METAR reported light ice pellets, so the pilot suspected freezing rain at altitude and delayed the departure.
Example Sentence 2
Ice pellets on the windshield during descent alerted the crew to possible structural icing.