Effects of Snow Cover
on forecasted temperatures

As the sun's rays hit the surface of the earth, much of it is absorbed by the surface (as in the diagram below). This in turn warms the air near the earth's surface, causing the temperature to rise.

If there is snow on the ground, some of the sun's energy will be reflected away by the snow, and some of it will be used to melt the snow. This means that there is less energy available to heat the earth's surface and consequently, the temperatures rise more slowly than would occur with no snow on the ground.

Forecast Tip:
When snow cover is present, forecast lower daytime temperatures than you would normally predict if there was no snow cover. At night, snow on the ground readily gives off heat. This causes rapid cooling. Forecast the overnight temperature to be lower than you would predict if there was no snow cover.

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Credits and Acknowledgments for WW2010.
Department of Atmospheric Sciences (DAS) at
the University of Illinois at Urbana-Champaign.