A third of the earth’s surface is made up of deserts, but none of them are the same. There are many types of deserts and, unlike what one may think, not all of them are limited to being a place where the sun shines and the heat suffocates us.
There are tropical, dry and sandy deserts like the Sahara, but there are also landscapes sparse of life full of ice, frost and darkness like Greenland. Whether cold or warm, all of them are characterized by having little rainfall, which conditions the forms of life that inhabit them.
Next We will know the different types of desert that exist their climatological characteristics and some species that can be found in them.
When we see the word “desert,” the first image that comes to mind for the vast majority is the Sahara: an extensive place of dune landscape, full of sand and without vegetation. This African desert has become the prototype of what we know as a desert and, in fact, its name comes from the Arabic “aṣ-Ṣaḥrāʾ al-Kubrā” which literally means “the Great Desert”.
This is why any landscape that resembles the Sahara in one way or another is easily identified as a desert: Atacama, Australia, much of the United States… However, It is not the heat or having a landscape made of sand that makes a territory considered a desert, but how much rain falls on it. For this reason it should not surprise us that places like Greenland, that large island-continent made practically of ice, qualifies as a desert, in fact, one of the largest.
Before talking more in depth about the types of desert, it is necessary to understand exactly what they are. Deserts are one of the 15 biomes that exist on Earth, that is, they are sets of ecosystems and these are characterized by having less than 225 millimeters of annual rainfall. As they are places with little rain, these territories are dry areas, which completely conditions the development of life, although it does not mean that no living organism lives there.
There is little diversity of organisms and, in fact, there is little organic matter, scarcity of nutrients and, generally, very few plant and animal species The few species that live there are very adapted to life in the desert, whether cold or hot, and on many occasions we find Extremophilous species. These can withstand very difficult living conditions such as water scarcity and extreme temperatures, with very high values, above 40ºC, or very low values, below -40ºC.
Having understood what deserts are, it is time to get into the subject and discover what types of desert exist. As we said, there are not only warm ones, such as the Sahara, but there are also cold ones and they can present other distinctive peculiarities.
1. Tropical deserts
We start with the prototypical deserts. tropical deserts They are those ecosystems that are located near the Earth’s equator Most of the known deserts, being close to the equatorial strip, receive a large amount of solar radiation, which makes them very hot places.
These deserts are formed due to the winds present at these altitudes, the trade winds, preventing the formation of clouds and preventing rain. Combined with the extreme heat, these places are very dry and can easily exceed 55ºC, depending on the time of year.
The Sahara Desert is the typical tropical desert, and so are the Syrian-Arabian Desert, which is practically the eastern continuation of the great North African desert, the Thar Desert and the Kalahari Desert. Part of the Australian desert would also fall into this category.
2. Polar deserts
Polar deserts are places where there is little rain, they have few plant and animal species, and they are large flat plains, just like tropical deserts. They are similar in many ways except one: Its highest temperature per year does not exceed 10ºC In fact, the average temperature in these places is -20ºC and can reach below -40ºC. It is very cold.
As the temperature is below the freezing point of water, in these places we do not find sand dunes as in the Sahara, but rather enormous and extensive ice sheets where it is difficult for any plants to grow. Examples of this are Greenland and Antarctica, with ice sheets 2 km thick.
3. Cold or mountain deserts
Cold or mountain deserts are those that, as their name indicates, They form at high altitudes, where ecosystems are located in places with very low temperatures, low pressure, little oxygen and little rain
This causes plateaus to form in some areas of the mountains where life is mainly composed of lichens. We find some deserts of this type in Tibet, Patagonia, the Andes and some areas on the periphery of the Arctic.
4. Monsoon deserts
Although the word “Monsoon” makes us think of torrential rains, the truth is that Monsoon deserts are like the others, dry and arid, but they are related to this climatological event These deserts do not form in the Monsoon zones, but in the coastal areas of the Indian Ocean as a result of the trade winds taking the precipitation to the interior areas and dumping it there, far away, leaving the coast without any rain. The Rajasthan desert is an example of this.
Coastal deserts are found on the western edges of continents that lie in the Tropics of Cancer and Capricorn Despite being close to the coast, they receive the impact of cold ocean currents which, together with the presence of the trade winds, maintain a situation of atmospheric stability that prevents precipitation from occurring, which translates into a lot of aridity.
In these places it is very rare for it to rain In fact, on average it rains only once every 5 or 20 years depending on the location. However, fog can appear that somewhat mitigates the lack of water and, in the places where it is most present, the ground is completely soaked, causing some grasslands to thrive and the occasional tree, cactus and lichen to grow. These fogs are equivalent to about 600 mm of “normal” rain.
We have some examples of these deserts in the coastal part of Western Sahara, Namibia, Australia and the desert between Chile and Peru.
6. Mid-latitude continental deserts
These deserts occupy wide areas ranging from central Asia, in Mongolia and China to Turkmenistan and the shores of the Caspian Sea. Examples of them are the Gobi, the Taklamakan and the Karakum, as well as the deserts of Iran, Iraq and Syria. We can also consider those in the western United States and Australia as deserts of this type.
The continental deserts of mid-latitudes in Asia have summer rainfall and a very strong thermal amplitude In summer they are warm places, with temperatures close to 25ºC, but winters are dry and harsh, dominated by the Siberian anticyclone and with temperatures below zero for several months in a row.
7. Subtropical deserts
Subtropical deserts are located near the equator, but are not impacted by the trade winds. They are areas with high atmospheric pressures that are far from the oceans and seas, so they receive little rain. In part, the Sonoran Desert could be considered a subtropical desert, although it is also worth saying that North American deserts have some peculiar features that we will see below.
8. Deserts of North America
North America is a very large region, large enough to have its own group of deserts. Although its deserts have characteristics typical of tropical and mid-latitude deserts, those that extend between the southwest of the United States and central Mexico have very interesting characteristics that make them different from the rest.
These include hyper-arid zones with almost no vegetation but, overall, removing the salt flats and dune fields, Its biomass is much greater compared to the rest of the deserts They are places where complex and highly diversified ecosystems are located.
The most characteristic is that of Sonora, which has very extensive vegetation, especially in the form of cacti of all types, heights and colors. One of its most distinctive cacti is the sahuaro (Carnegiea Gigantea), which can measure 15 meters in height and live up to 200 years. The flowers of this plant open at night to avoid exposure to excessive heat and its main structure reserves large amounts of water.
Barrier deserts form in regions that are surrounded by large, high mountain ranges. Mountains act as barriers, preventing the entry of wind and clouds loaded with precipitation, making them dry places not because of the heat or the extreme radiation of the sun, but because they are deprived of rain. An example of this type is the Judean Desert in Israel.
10. Australian deserts
The case of the Australian deserts also deserves special attention, since there are no extreme deserts on that continent and its arid areas, from a climatic point of view, are rather limited. In fact, the territory receives rainfall between 150 and 400 mm annually, which makes it In many desert places the rule that they must be places with little rain is not met
However, these rains are extremely irregular and can provide a lot, in a ratio of 1 to 10. This means that a lot of vegetation can grow in a specific place at one time because it has started to rain frequently, but at a given moment it no longer rains. There is precipitation again, causing all the fertile land to dry completely. Ecosystems change a lot and the only vegetation that is guaranteed survival is extreme vegetation.
The Australian interior is very dry, so much so that a large fire occurs almost every year, fires produced for thousands of years by the natives and, since the modern Australian has settled, the new settlers. These fires destroy the plants weakest to fire, but favor the growth of pyrophytic and xerophytic plants that resist it very well. The most characteristic vegetation is mulga (Acacia aneura) and some eucalyptus.
11. Extraterrestrial deserts
Extraterrestrial deserts? What are they doing here? Taking into account the main characteristics of deserts, dry places, without precipitation, with extreme temperatures and little life, the landscapes of other worlds fall within this group. Any planet where there are winds and have a solid surface has deserts, Mars being the closest to our world
Extraterrestrial deserts strictly comply with the characteristic of not having life. Well, at least as far as we know, there is no life on Mars, and this can be used for future research on the red planet since this world would serve to simulate how life would develop on other planets that, until now, have not been “invaded” by any organism.
