How can snow fall with surface temperatures above freezing?
It is a fact that a snowflake, composed of frozen water, will begin to melt when it encounters temperatures greater than 32 F. However, this melting process takes time; ice does not melt into liquid instantly. It is the idea that melting requires time that is essential in understanding how snow can reach the surface with temperatures above freezing. Most precipitation begins in the form of snow high up in clouds, as the temperatures in almost all wintertime clouds are below freezing. Rain is observed at earths surface when falling snowflakes encounter a region where temperatures are above freezing. If the snowflake is in this warm environment long enough, it will melt into a raindrop. But if a snowflake falls through a relatively thin layer of warm air, it might not have enough time to melt before it hits the surface. If this thin layer with temperatures above freezing is near the surface, snow can result, even if temperatures are above freezing! How thick does a layer of air need to b
