Polar desert: Difference between revisions

'''Polar deserts''' are areas with annual [[Precipitation (meteorology)|precipitation]] less than {{convert|250|mm|in}} and a mean [[temperature]] during the warmest month of less than {{convert|10 °|C|F}}. Polar [[desert]]s on [[Earth]] cover nearly 5 million square kilometers and are mostly hard [[bedrock]] or [[gravel]] plains. [[Sand dune]]s are not prominent features in these deserts, but snow dunes occur commonly in areas where precipitation is locally more abundant. Temperature changes in polar deserts frequently cross the freezing point of water. This "freeze-thaw" alternation forms patterned textures on the ground, as much as 5 meters in diameter.