graupel

1. (uncountable) A precipitation that forms when supercooled droplets of water condense on a snowflake.Examples: "Is it desirable in giving the falls of hail to draw a distinction between "graupel" and true hail?"; "November.— […] Smart shower of graupel (i.e. frozen snow in pellets), with snow at 9 p.m. on 10th."; "In a paper in this month's Petermann's Mittheilungen Prof. H. Fritz treats of the Geographical Distribution of Hail. […] [B]alls of true hail hav[e] an icy structure, whereas the balls of graupel are only small pellets of snow. […] With increase in latitude and in height the fall of graupel increases and that of hail decreases, while hailstones of large size are most frequent towards the equator."Synonyms: granular snow, hominy snow, popcorn snow, soft hailuncountable

2. (countable) A small ball of rime resulting from this process.Examples: "It is established that graupels and hailstones are cone-shaped with rounded apexes and that they become egg-shaped as a result of growth during descent."; "[W]hen an ice or snow crystal collides with supercooled droplets, the droplets will freeze on the surface of the crystal to form rime. […] [C]ontinued riming will eventually produce a particle that is completely covered by rimes such that the original crystal shape can no longer be recognized. The particle now becomes a graupel (sometimes also called a soft hail or snow pellet). […] By convention, a graupel should be smaller than 5 mm in diameter. If it becomes greater than 5 mm in diameter (2.5 mm in radius) it will be called hail."Synonyms: snow pelletcountable