A hot desert is a part of the world that has high average temperatures and very low precipitation. These areas need to have less than 250mm of rainfall per year to be classified as a desert. The stereotypical view of a desert is one totally devoid of life and rolling sand dunes, but deserts do support life and the plants and animals that live in the deserts around the world have adapted to cope with the extreme climate.
Above - The Thar desert in Rajasthan
As you can see on the map, hot deserts are found on nearly every continent, from the Atacama Desert in South America, the Chihuahuan Desert in North America, the great Sahara in Africa, the Thar Desert in Asia and the Great Sandy Desert in Australia. Although very different they do have common characteristics.
The physical characteristics of hot deserts.
The climate graph reveals the climate for Jaisalmer, in the Thar Desert in Rajasthan. The desert is very dry and often hot. As can be seen there are many months when the average temperature is well above 30ºC and day time temperatures can top 50ºC!
You can also see that annual rainfall averages less than 250mm per year, and that rain often comes all at the same time. This poses big problems for plants, animals and people that live there. The rest of the year is very dry. There is a lot of direct sunlight shining on the plants. The soil is often sandy or rocky and unable to hold much water. Winds are often strong, and dry out plants. In the Thar Desert the Loo wind blows from south west to north east and can kill people who are exposed to it through heat stroke.
The interdependence of desert climate, water, soils, plants, animals and people.
The living things that inhabit hot deserts are linked to each other and their physical environment. Many of the elements of the biome are interdependent upon one another. People are dependent upon their animals in deserts, for food, milk and as use as pack animals. For example, the Beja people use camels in North East Africa through Sudan, Egypt and the Sahara Desert.
As can be seen in the image below, while plants rely upon soils for their nutrients, the soils rely upon plants to provide extra nutrients through dead vegetation and fixing chemicals from the air into the soil. Plants also help soils retain more water, by providing shade from the searing desert sunlight. Plants also tie the soil together, preventing soil erosion and excessive leaching of nutrients in wetter periods. Oases exist in low points in the desert, where water can be found closer to the surface and some agriculture is possible.
Just as in other biomes, food webs also exist. A hawk might prey upon a desert lizard or snake, which in turn feeds upon rats or insects, which feed upon desert plants such as cacti or annual grasses or flowers.