Eli5: why is thundersnow so rare?
In: Planetary Science
For best results, the base of the thunderstorm has to be above freezing, and the upper layers colder than about -22C. This allows for the liquid/solid transition in the lower layers which in part creates an electrical potential. The other part is the -22C where super-cooled liquid transitions to solid ice, adding more potential. You see this where Cumulonimbus (thunderstorm) clouds turn from lumpy/puffy liquid droplets to the fuzzy top of ice crystals. Enough potential and you get a electrical discharge within the cloud from high to low, or from high to surface – lightning.
If the whole cloud is ice crystals, it’s hard to generate enough electrical difference between the top and bottom.
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