Cloudy winter days make the snow melt faster, says a study from the University of Utah. Snow is designed to stay cold in three ways: by deflecting the sun’s heat with it’s bright white color and crystalline structure, the bright white reflecting heat back at night, and sublimation, evaporating from snow to vapor, similar to the way sweat evaporates from our skin to keep us cool.
Cloudy humid days, however prevents snow from deflecting, reflecting and sublimating warming the snow. That is why a few humid days with temperatures hovering around the freezing point create large melt events and even minor flooding.
Do your own experiment by watching snow that remains in shadows even on warm sunny days. Then watch what happens to that same snow during gray days and nights — quickly, though, before it’s all gone.