Snow cover and it’s impact on temperatures

With the deep snowpack over the southern plains and middle Mississippi river valley. You can see the impact this has on the air temperature. First you have to know how the sun actually heats the air indirectly. The air heats up by incoming solar radiation (sunlight) hitting the ground and heating it up. The ground then in turn heats the air right above the ground. When you have a deep snowpack this process is reduced dramatically. There are a few factors that affect this. The first factor is snow, especially fresh snow, has a very high albedo which means it reflects a lot of the incoming sunlight. Snow can reflect up to 88% of the incoming solar radiation which means none of that sunlight goes into heating the ground. Some of the solar radiation that doesn’t get reflected does get absorbed by the snow. Problem is this energy goes into melting and evaporating/sublimating the snow. Which leads to very little of the suns energy left over to actually warm things up thus making the air temperature much cooler.

One way to think about this is if you were trying to boil water on your stove. If you put 2 pots on the high setting and filled one with warm water and one with ice & cold water. The one with warm water would boil first because you stoves heat has less work to so. The ice water would take longer because the stove has to use much more energy to melt the ice then boil that water. This is true when it comes to the sun warming the air, the less work it has to do melting, evaporating etc…. the faster it can warm things up.

Below is a great example of this process from the middle of the country. Notice the cold spots where there is snow on the ground. The skies are clear here so all that white is the snowpack reflecting the sunlight ( That Albedo thing again).

Here’s a good comparison with just the snow cover:

Compared to the temperatures, see how the snow and cold line up.