🌨️ Graupel Formation: Riming of a Snow Crystal, Collection Efficiency and Hallett-Mossop Splinters

Drop a planar snow crystal through a supercooled cloud and watch it rime into graupel: droplet collection efficiency from the Stokes number, rime infilling then growth, rising fall speed, and Hallett-Mossop secondary ice splinters in the -3 to -8 degC band.