■ FIGURE 8.2 Map of the contiguous United States, showing average annual number of days with snow cover.

What areas of the United states average the greatest number of days with snow cover?

The areas of the United States that average the greatest number of days with snow cover.

The areas of the United States that average the greatest number of days with snow cover is the northern Great Lakes and mountain regions of the Western United States.

Several common characteristics are shared by microthermal climates. All humid climates experience a surplus of precipitation over potential evapotranspiration, and they receive a year-round precipitation. The subarctic areas that are characterized by bitter cold and winter droughts resulting from dry air are an exception to this. A precipitation maximum is produced in the summer by combining the high frequency maritime tropical air masses in summer and continental polar air masses in winter with strong summer convection. The length of period at which snow remains on the ground increases toward the poles and continental interiors.

Apart from highland areas, all three microthermal climates experience a significant snow cover. The effectiveness of warming by solar radiation will decrease by the high albedo of snow, and it contributes to the cold winter temperatures that are experienced at these locations. The variable and unpredictable nature of the weather is especially apparent in the humid microthermal climates.

The northern Great Lakes and the mountain regions of the Western United States are the areas of the United States that average the greatest number of days with snow cover.