Characteristics and climate of deserts

Deserts have extreme temperatures. During the day the temperature may reach 50°C, when at night it may fall to below 0°C. Deserts have less than 250 mm of rainfall per year. The rain can be unreliable. Most deserts are found between 20° and 35° north and south of the equator.

Monthly rainfall and temperature bar graph in desert regionsWorld Meteorological Organisation, 2013

The Sahara is the largest desert, covering 9 million km2.

There are three factors which form desert areas:

  1. the presence of high pressure, creating cloud-free conditions
  2. cold ocean currents
  3. mountain ranges to create rain shadows
The rain shadow effect in Patagonia, South AmericaDiagram of the rain shadow effect in South America