Is Madison, Wisconsin in a snow belt? What is the origin of the term?
While the lakes around Madison provide many winter recreation activities, the local lakes do not yield a snow belt.
We refer to agricultural regions in the United States as ‘belts’, such as the cotton belt and wheat belt. This phrase has expanded to cultural (e.g. bible) and climatic regions. The “snow belt” refers to the area downwind of the Great Lakes where the climate includes large amounts of snowfall.
The snow belt exists because snowfall can be enhanced when storms cross large lakes, called the “lake effect.” When cold air moves across a large expanse of warmer lake water, the lower air is warmed and moistened by the water. This enhanced evaporation increases the moisture content of the air mass; this moisture can then precipitate as snow downwind.
The distance the air mass travels over the water, called the fetch, is important in generating snowfall. Generally, larger fetches give more time for the air mass to accumulate moisture, producing more snowfall. A minimum fetch of about 60 miles is needed for lake effect snowfall. Wisconsin, Ohio, Pennsylvania and New York all have major snow belts downwind of Lakes Superior, Erie and Ontario.