Aridity

Arid regions of the Western United States as mapped in 1893

Aridity is the condition of a region that severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most arid climates are located in the subtropics; these regions include parts of Africa, Asia, South America, North America, and Australia.