Adiabatic Compression

Adiabatic compression is the process by which sinking air is compressed heated as it is subjected to increasing pressure from the air above it. The air also dries since the spread between the temperature and dew point increases. When air moves down the hill in Duluth due to an offshore wind direction, the air also warms and dries. If snow is falling, the drying of the air erodes some of the snow due to sublimation. Sublimation is the process by which water changes phase from ice to water vapor. If the temperature at the top of the hill is not much below 32 degrees Fahrenheit, the air will try to warm above freezing as it sinks. The warmer temperature will retard snow accumulation or at least cause a soggier snowpack. Some of the warming is balanced off by cooling due to melting or sublimating snow.