graupel

plural graupels

1. uncountableclimatologyA precipitation that forms when supercooled droplets of water condense on a snowflake.

   Is it desirable in giving the falls of hail to draw a distinction between "graupel" and true hail?

   1873 April, “The Leipzig Conference”, in Symons’s Monthly Meteorological Magazine, volume VIII, number LXXXVII, London: Edward Stanford, […], →OCLC, page 42

   3 more examples

   November.— […] Smart shower of graupel (i.e. frozen snow in pellets), with snow at 9 p.m. on 10th.

   1877 January 24 (date written), Frederick E[rnest] Sawyer, “November”, in Meteorology of Brighton, 1876, [Brighton, East Sussex?]: [s.n.], published [1877], →OCLC, page 2

   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.

   1876 November 2, “Notes”, in Nature: A Weekly Illustrated Journal of Science, volume XV, London; New York, N.Y.: Macmillan and Co., →OCLC, page 17

   The steam of the horses and their breath came back in turbid clouds, and the snow, or soft hail (now known as graupel), cut white streaks through them into travellers' eyes, and danced on the roof like lozenges.

   1894, R[ichard] D[oddridge] Blackmore, “A Wager”, in Perlycross: A Tale of the Western Hills, London: Sampson Low, Marston, & Company […], →OCLC, page 238

   Synonyms: granular snow, hominy snow, popcorn snow, soft hail

2. countableclimatologyA small ball of rime resulting from this process.

   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.

   1951 September 15, Donald G. Yerg, “Tikhomirov, E., On the Shape of Graupels and Hailstones (O Forme Krupy i Grada). Meteorologiia i Gidrologiia, 2, No. 9: 66–67, 1936”, in Annotated Bibliography on Snow, Ice, and Permafrost […] (SIPRE Report; 12), [Hanover, N.H.]: Snow, Ice, and Permafrost Research Establishment, Corps of Engineers, United States Army, →ISSN, →OCLC, page 340, column 2

   1 more example

   [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.

   2013, Pao K[uan] Wang, “The Shape and Size of Cloud and Precipitation Particles”, in Physics and Dynamics of Clouds and Precipitation, Cambridge, Cambridgeshire: Cambridge University Press, →ISBN, page 30

   Synonyms: snow pellet