Snow covers impact on temperatures
Snow cover can have huge effects on daytime and nighttime temperatures. It’s not often we get a lot of snow cover in the Carolinas but when we do it can help to keep daytime highs down and make overnight lows drop to record levels. The reason this happens is something we call Albedo which is the reflection coefficient of snow. Basically this is the amount of solar radiation that the snow reflects. Fresh snow happens to have an albedo of 80-90%. Which means during the day 80-90% of the sunlight is reflected straight back up not allowing temperatures to warm. this also is why if you ski when the sun is out you can get a pretty good sunburn because you are getting solar radiation from above and below. Normally minus snow cover the sunlight would be absorbed by the ground which then would heat the air.
During the night time this same albedo helps to cool the ground very fast allowing for temperatures to plummet especially under clear skies. Some of the coldest low temperatures ever recorded in the history of Charlotte have come after a snow storm. When the ground was covered with fresh snow and arctic high pressure built in and cleared skies out. The most recent snow cover is a good example.
This snow cover from the Christmas weekend storm is visible from space. This same reason we can see the snow through the visible spectrum of light is the same process reflecting all our incoming solar radiation.
Even as temperatures begin to warm the next few days the afternoon high temperatures and the nighttime low temperature forecasts have to be adjusted for the snow cover. This is not only due to the albedo effect but because more of the sunlight’s incoming energy will be going into melting the snow and not heating the air. This is something that no weather model will forecast because they don’t take into account what type of ground cover there is. So watch as the next few days where the snow is the deepest that the high temperatures and low temperatures will actually be a few degrees below what many people think. Just one more impact of the historic Christmas weekend snowfall.
