Snow’s sublime way of vanishing

Long before winter was over, while it was still snowing almost everyday, my wife worried about if and when all the accumulation around the house would ever disappear. I said “No need to worry!” 

Well, the past days are proving me right as we’ve moved in a few days from temperatures in the thirties into the upper sixties and with it, snow has begun to melt creating rivulets everywhere and also trying unsuccessfully to percolate into a ground that’s still frozen. 

Then, there that mysterious and invisible phenomenon called “Sublimation” in which snow goes from solid directly into gas or water vapor. Certain atmospheric conditions help with that. Dry air can absorb more moisture than damp air conditions, and pull more moisture from the ground into the atmosphere. 

High winds can also blow moisture into the air and away from the area where it initially fell. And finally, the warmer the air gets, the more that the sun shines and the most energy is available for snow to turn directly into vapor. When you get combinations of these factors like warm, dry winds (Chinook in the Rockies, Foehn in the Alps) evaporation and sublimation are suddenly boosted.

So much so, that on a dry, windy day, up to around two inches (5 cm) of snow can sublimate into the atmosphere. That translates to about 72,000 gallons of water for each football field-sized area of snow. 

This said, I’m woefully unable to say how many gallons are melt directly from snow to water!