The desert is a biome characterized by low rainfall. It can occur in both tropical and cold climates. The vegetation is sparse, in which the cacti are predominant.
These regions are usually close to the lines of the tropics and lose moisture through the trade winds and the action of cold sea currents.
The deserts occupy extensive territories, located mainly in the tropical and subtropical zones .
In the boreal hemisphere, arid regions cover a wide area, from almost all of North Africa and the Near East (Arabia), from Asia to Pakistan, China and Mongolia (Gobi Desert).
In North America, they are located in the southwest of the United States and in the north of Mexico (Mojave and Sonora deserts).
In the southern hemisphere, the deserts of the central region of the Australian continent, South Africa (Namibia and Kalahari) and those of South America, Patagonia and the coastal zone of Chile (Atacama) and Peru are highlighted.
The precipitations are very scarce and can occur in any season. This lack of rain is a challenge for the living beings that live there.
In addition, temperatures vary greatly between day and night, reaching a temperature difference of 35 ° C. The winds are constant and often very violent, causing sandstorms.
The soil of the desert regions is quite shallow, with a sandy surface layer covered by a mantle of stones and gravel.
Wind is a permanent erosion agent of this type of soil; sand dunes may occasionally be carried by the winds, but, contrary to what one might think, they do not constitute the dominant landscape.
The vegetation is scarce and adapted to an insufficient supply of water. Of note are the cacti in America and the palm trees in Africa and Asia; in addition, clumps of herbaceous plants also occur.
There are plants capable of storing water, such as cacti, while others (such as certain shrubs) develop very deep roots capable of reaching the water table.
Many species of desert plants have rapid life cycles: they sprout, they grow, they bloom and they bear fruit very quickly, when there is a supply of rainwater. Then they die and only the seeds remain, waiting for a new rain so they can sprout and restart the cycle.
The photo above plant is endemic to the Namibian desert, where the environmental conditions are extremely strict: it only rains every four or five years, with annual rainfall less than 2 mm.
The desert fauna is adapted to the extreme conditions of these places. Many animals are nocturnal, because at these times the heat and evaporation are lower than during the day. Others shelter under rocks or inside burrows, like scorpions and reptiles.
Camels, to prevent loss of water, reduce your sweating and get energy by degrading the fat stored in your hump.
The coyote, the puma, and the rattlesnake are some of the desert animals in America; insects that, like plants, are adapted to the occurrence of occasional rainfall are also abundant.
The desert animals, like the gazelle and the camel, usually have a coat of light colors, which reflect the heat better than the dark ones.