Climate Fact: North American and Eurasian Snow
Snow is both a product of the weather and a weather maker. It has long been recognized that snow exhibits a cooling effect on local and regional scales. Snow reflects more sunlight than bare ground, meaning that it absorbs less energy. More snow cover also means soils stay moist for longer following the spring melting than they otherwise would. More soil moisture means that more of the sun’s energy that would have been spent heating the ground is instead spent evaporating water. In North America, lots of snow over the continent affects the storm track, or the latitudinal band where travelling cyclonic high and low pressure systems are most common. More specifically, the cold temperatures the snow cover induces eventually force the storm track over North America to veer south. As it does this, the storm track downstream in Eurasia veers north, allowing warmer air masses to penetrate further into the continent than they otherwise would. The presence of these warmer air masses generally means less snow there. Thus, years of above average snow cover in North America tend to be years of below average snow cover in Eurasia.
Seasons: Winter, Spring
Source: Sobolowski, S et al. “Modeled Climate State and Dynamic Responses to Anomalous North American Snow Cover.” Journal of Climate 23 (2010): 785-799.