The climate of Antarctica is the coldest on Earth. The continent is also extremely dry (it would be a desert virtually anywhere else on Earth, but it is mathematically impossible for any location on Earth that as a mean annual temperature of <14°C to be even a steppe, let alone a desert, under the Köppen classification scheme), averaging 166 mm (6.5 in) of precipitation per year. Snow rarely melts on most parts of the continent, and, after being compressed, becomes the glacier ice that makes up the ice sheet. Weather fronts rarely penetrate far into the continent, because of the katabatic winds. Most of Antarctica has an ice-cap climate (Köppen classification EF) with very cold, generally extremely dry weather.