How snow 'melts' when temperatures are below freezing
By: News 12 Meteorologist Mike Rizzo
We all know snow loves to stick around – especially when it’s cold outside, and the sun along with milder temperatures helps to clear our streets and sidewalks from the slushy and icy aftermath.
But what happens when the temperatures don’t go above freezing? Does the snow just stay until we have warmer temperatures? Well – the answer is both yes and no.
On days where the temperatures are below freezing, the snowpack lingers and doesn’t melt much, but it seemingly “vanishes” as if it is melting. But where are the puddles?! If you didn’t catch that – look again on a sunny cold morning with a snowpack. Then look again later in the day. It seems like the snow is melting but the ground around the snow is dry. There’s no liquid! In chemistry, this is called sublimation.
Sublimation occurs when bright warm sunlight directly reaches the snow. The sun’s intense energy and warm direct rays forces the frozen “solid” snow to skip the melting phase completely and go straight into the atmosphere as water vapor. It essentially just vaporizes. Think of the sun like a laser beam that vanishes anything that it touches.
Melting occurs when the air around the snow is above freezing, thus melting the solid to a liquid – making puddles.
When you have both sublimation and melting together, the snowpack reduces quickly. But when you have just sublimation, the snow reduces slowly just during the daytime hours when the sun is up.
So, the next time a big snowstorm happens with freezing days to follow, know that the snow will stick around for a bit longer. Just hope the sun comes out!