Also: "Soft Hail"
A form of precipitation which looks like round pellets. Macroscopically, graupel resembles small beads of polystyrene.
Graupel is subject to rolling and can collect in pockets. It can also form a layer with a great deal of pore space and poor bonding. The pellets themselves are snowflakes which accumulated rime ice as they fell through certain atmospheric layers.
Graupel can sometimes form a weak layer in the snowpack which can fail and cause an avalanche. However, because it rolls the layer may not be consistent over a wide area. If there is no firm bed surface underneath and/or an insufficient slab above it may also cause a collapse of the snowpack without a slab avalanche. A graupel layer usually stabilizes within a couple days or less.
Meteorologists once used the term "soft hail" but no longer do.
|A plate type crystal with rime on it.||Graupel. Original crystal habit can no longer be determined.|
|All micrographs are by the USDA and as government products made with public funds are in the public domain.|
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