Definition
A form of frozen precipitation made up of small, soft, white pellets formed when supercooled water droplets freeze onto a falling snowflake, coating it in rime ice. Graupel pellets are typically 2 to 5 millimeters in diameter, crumble easily when touched, and are distinct from both snow and hail.
Plain English
Small, soft, white ice pellets that fall like snow but feel more like tiny crunchy beads. They form when snowflakes pick up a coating of frozen water droplets on their way down.
Context Anchor
Pilots may encounter graupel in aviation weather discussions, forecasts, pilot reports, or during cold-weather operations near showers or unstable clouds.
Derivation
From the German word Graupel, meaning 'soft hail' or 'pearl barley.' The grain comparison reflects the small, rounded, brittle shape of the pellets.
Why Pilots Care
Graupel indicates the presence of supercooled liquid water and can contribute to airframe icing or reduced visibility.
Analogy
Think of a snowflake that fell through a freezer full of mist and came out wearing a crunchy white shell.
Grounding Statement
Picture a snowflake falling through a cold cloud and picking up frozen droplets until it becomes a small, soft ice pellet.
Intuition Check
Graupel is not ordinary snow, and it is not true hail. It is a soft snow pellet formed by frozen droplets coating a snow crystal.
Example Sentence 1
The pilot reported brief showers of graupel as the cold front passed overhead.
Example Sentence 2
Heavy graupel was falling at the airport, prompting a delay until runway conditions could be checked.