The 11 types of desert, and their characteristics

This is a classification of the most important types of desert, summarized.

One third of the earth's surface is made up of deserts, but none of them is the same. There are many types of deserts and, unlike what one might think, not all of them are limited to being a place where the sun rages and the heat suffocates us.

There are tropical, dry and sandy deserts like the Sahara, but there are also lifeless landscapes full of ice, frost and darkness like Greenland. Whether they are cold or hot, they are all characterized by low rainfall, which conditions the life forms that inhabit them.

In the following we will know the different types of desert that there areTheir climatological characteristics and some species that can be found in them.

Types of desert, classified and explained

When we see the word "desert" the first image that comes to mind for the vast majority is the Sahara: a vast place of dune landscape, full of sand and without vegetation. This African desert has become the prototype of what we know as desert and, in fact, its name comes from the Arabic "aṣ-Ṣaḥrāʾ al-Kubrā" which means, literally, "the Great Desert".

This is why any landscape that resembles the Sahara in one way or another is easily identified as 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 to be considered a desertbut how much rain falls on it. For this reason we should not be surprised that places like Greenland, that great island-continent made practically of ice, qualifies as a desert, in fact, one of the largest.

Before talking further about desert types, 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 that receive little rainfall, these territories are dry areas, which completely conditions the development of life, although this does not mean that no living organism inhabits them.

There is little diversity of organisms and, in fact, there is little organic matter, scarcity of nutrients and, in general, very few plant and animal species.. The few species that live there are very adapted to life in the desert, whether it is cold or hot, and in many occasions we find extremophile species. These can withstand very difficult living conditions such as water scarcity and extreme temperatures, which can be very high, above 40ºC, or very low, below -40ºC.

Having understood what deserts are, it is time to go into the subject and discover what types of desert exist. As we said, there are not only hot deserts, such as the Sahara, but there are also cold deserts and they may have other distinctive features.

1. Tropical deserts

We begin with the prototypical deserts. Tropical deserts are those ecosystems that are located near the terrestrial 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 because of 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, as 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 with little rainfall, few plant and animal species and large flat plains, as is the case with tropical deserts. They are alike in many ways except one: their highest temperature per year does not exceed 10ºC.. In fact, the average temperature in these places is -20ºC and they can be 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 huge and extensive ice sheets where it is difficult for any plant 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 which, as their name suggests, are formed at high altitudes, where they are found in the mountains, are formed at high altitudes, where ecosystems are located in places with very low temperatures, low pressure, low oxygen and little rainfall..

This causes plateaus to form in some mountain areas where life is composed mostly of lichens. Some deserts of this type are found 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 other deserts, dry and arid, but they are related to this climatological event.. These deserts are not formed in monsoon areas, but in the coastal areas of the Indian Ocean as a result of the trade winds that carry rainfall to inland areas and discharge there, far away, leaving the coast without any rain. The Rajasthan desert is a case in point.

5. Coastal deserts

Coastal deserts are found on the western edges of the continents that lie on 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, maintains a situation of atmospheric stability that prevents precipitation, which results in great aridity.

In these places it rarely rains. In fact, on average it rains only once every 5 or 20 years depending on the place. However, fogs can appear that mitigate the lack of water and, in the places where it is more present, the ground is completely soaked, causing some meadows to prosper and some trees, cactus and lichens to grow. These fogs are equivalent to about 600 mm of "normal" rainfall.

Some examples of these deserts are the coastal part of Western Sahara, Namibia, Australia and the desert between Chile and Peru.

6. Mid-latitude continental deserts

These deserts occupy wide extensions that go from the center of Asia, in Mongolia and China to Turkmenistan and the shores of the Caspian Sea. Examples are the Gobi, the Taklamakan and the Karakum, as well as the deserts of Iran, Iraq and Syria. We can also consider as deserts of this type those of the western United States and Australia.

Asian mid-latitude continental deserts have summer rainfall and a very high 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 freezing 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 rainfall. In part, the Sonoran Desert could be considered a subtropical desert, although it is also worth mentioning 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 southwestern United States and central Mexico have some very interesting characteristics that make them different from the rest.

These include hyper-arid areas with almost no vegetation but, overall, excluding salt flats and dune fields, their biomass is considerably higher compared to the rest of the deserts.. These are places where complex and highly diversified ecosystems are located.

The most characteristic is that of Sonora, which has a 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 so as not to be exposed to excessive heat and its main structure reserves large amounts of water.

9. Barrier deserts

Barrier deserts form in regions that are surrounded by large, high mountain ranges. The mountains act as barriers, preventing the entry of wind and precipitation-laden clouds.The desert is dry, not because of the heat or the extreme radiation of the sun, but because it is deprived of rainfall. An example of this type is the Judean desert in Israel.

10. Australian deserts

The case of Australian deserts also deserves special attention, since there are no extreme deserts in that continent and its arid areas, from a climatic point of view, are rather limited. In fact, the territory receives rainfall of between 150 and 400 mm per year, which means that in many desert areas there is no rainfall. many desert places do not comply with the rule that they must be places with low rainfall..

However, these rains are extremely irregular and can provide a lot, in a ratio of 1 to 10. This means that one season a lot of vegetation may grow in a particular place because it has started to rain frequently, but at a given time there is no more rainfall, causing all the fertile soil to dry up completely. Ecosystems change a lot and the only vegetation that is assured of survival is extreme vegetation.

The Australian interior is very dry, so much so that almost every year there is a fire of great proportions, fires produced for thousands of years by the natives and, since the modern Australian has settled, the new settlers. These fires kill the plants that are weakest to fire, but favor the growth of pyrophytes and xerophytes that resist it very well. The most characteristic vegetation are the 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 into this group. Any planet where there are winds and have solid surface have deserts, Mars being the closest to our world..

Extraterrestrial deserts comply to the letter 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, so far, have not been "invaded" by any organism.

Bibliographical references:

• Manrubia, S.C. (2012) "Astrobiology: In search of the limits of life". CSIC-INTA.
• Mucina, L. (2019) "Biome: evolution of a crucial ecological and biogeographical concept". New Phytologist.
• Gurera, D., Bhushan, B. (2020) “Passive water harvesting by desert plants and animals: lessons from nature”. Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences.
• Alcaraz Ariza, F.J. (2012) “Desiertos y semidesiertos”. Universidad de Murcia.