Why is Antarctica a desert?
Despite Antarctica's thick ice, it's classified as a desert because very small amounts of
moisture falls from the sky. The inner regions of Antarctica relieve an average of 2
inches of precipitation, mostly in the form of snow each year.
Unlike other deserts, there is not much evaporation in Antarctica, so the relatively little
snow that does fall, doesn't go away again. Instead it builds up over hundreds and
thousands of years into enormously thick ice sheets.
This precipitation doesn't fall as water, but as snow, the "water equivalent" is the amount
of water you would get if the snowfall was collected and melted.