GCSE Geography | What are Hot Deserts Like? (Hot Deserts 1)

Hot deserts are found between 20° and 30° north and south of the Equator. They cover approximately 14% of the global land surface. The largest hot desert is the Sahara desert, in northern Africa, covering 9 million square kilometres. Other hot deserts include the Arabian Desert in the Middle East, the Kalahari Desert in south-western Africa, the Atacama Desert in Chile, the Australian Desert (which covers a huge area of the country), the Thar Desert in India and Pakistan, and the Chihuahuan, Mojave, Sonoran Deserts, which all make part of the Western Desert in south-western USA.

Hot deserts are bordered by semi-arid areas, such as the Sahel across Northern Africa, south of the Sahara Desert. These semi-arid regions are at risk of desertification.

Hot desert climate

Hot deserts are extremely arid with less than 250 millimetres of rainfall per year.

Annual rainfall totals are extremely low in hot deserts, but they are also unreliable too - there are some parts of the Atacama Desert in Chile where it hasn't rained for 400 years, whereas other areas may only receive one millimetre of rainfall a year. Usually hot deserts receive around 100–200 millimetres of precipitation annually.

Hot deserts are where we find our highest temperatures on Earth - the highest ever recorded temperature is 56.7 °C, which was recorded on 10th July 1913 at Furnace Creek Ranch, in Death Valley, in the United States.

The location of the hot deserts can be largely explained by global atmospheric circulation. At these latitudes air that has risen at the Equator descends forming a persistent belt of high pressure, which explains the lack of cloud and rain. Cloudless skies lead to high levels of insolation during the day, resulting in extremely high temperatures, but the lack of cloud cover also means that temperatures can plummet to below freezing at night during the winter. Hot deserts experience a huge diurnal temperature range - this is the difference in temperatures between day and night, which can exceed 35°C.

Hot desert soils

In hot deserts soils tend to be sandy or stony, with little organic matter due to the general lack of leafy vegetation and water, so they are not very fertile. They are formed mainly by weathering which creates deposits of sand and other loose material, and are usually around a metre deep, apart from where sand dunes have been able to form enabling deeper soils to potentially develop. However sand dunes are not classed as soils because they lack organic matter.

Hot desert soils are dry but can soak up water rapidly after rainfall, however the water will evaporate quickly. Evaporation draws salts to the surface, often leaving a white powder on the ground.

In some desert regions irrigation has been used to make land productive for agriculture.