Why is Antarctica considered a desert despite its vast ice sheet?

Antarctica is classified as a desert primarily because it receives extremely low levels of precipitation. While many people associate deserts with sand and heat, the scientific definition is based on aridity; many authorities define a desert as an area receiving less than 10 inches (250 mm) of precipitation per year.123

The vast ice sheets covering the continent do not contradict this classification. Instead, they represent accumulated water stored over vast periods of time in a region where the atmosphere is exceptionally dry. The Antarctic atmosphere contains only about one-tenth of the water vapor concentration found in temperate latitudes, and most of the moisture that does reach the continent precipitates as snow along the coastal margins.12

The interior polar plateau is particularly arid, receiving only about 2 inches (50 mm) of liquid water equivalent per year. This lack of moisture, combined with frigid temperatures and minimal plant life, confirms its status as one of the world's largest "technical" deserts.123