Weather Tidbits: Melting Snow Below Freezing

We’ll be discussing why snow can melt at below freezing temperatures in this edition of Weather Tidbits. Even when measured above ground air temperatures are below freezing, snow can melt if the sky is sunny. Not so much on a cloudy day and especially at night. The sun can still warm the ground temperatures enough to melt some of the snow via solar radiation. Snow reflects about 90% of the sun’s energy and absorbs about 10%, and that 10% is used for melting. Spots to see the most efficient snow melting include the sun facing side of a building and on blacktop asphalt. Dark surfaces absorb solar radiation and heat up more efficiently than lighter surfaces. The asphalt temperatures can be over 10 degrees warmer than the air temperature on a sunny day. The melting process becomes even more effective as the sun angle continues to increase through winter.