A desert is an arid region with very little rain, and therefore the weather conditions are hostile to plant and animal life. The lack of vegetation in the desert exposes its surface to erosion processes. About a third of the Earth’s surface is arid or semi-arid, and this includes much of the polar regions where precipitation is low, and these polar regions are called “polar deserts”. Deserts are classified according to the amount of rain that falls, the temperature that prevails, the causes of desertification, or the geographical location.
Deserts are formed by weather factors, as the large differences in temperature between day hours at noon, for example, and night lead to the breaking of rocks into pieces. Although it rarely rains, heavy rains rarely occur, leading to flash floods. The rain falling on the hot rocks can cause shattering and erosion into fragments scattered on the ground. These fragments are exposed to more fragmentation by the wind.
Sand particles crumbled in sand or dust storms are taken away by the wind. Hard surfaces in the environment are scraped off with grains of sand. The rocks are softened, and the wind transforms the grains of sand into homogeneous shapes, so they are laid as layers on the ground or stacked to form sand dunes. In other deserts, the surface is flat, devoid of sand, and consists of a layer of smooth rocks. These areas are known as pavements.
In some deserts, there may be rocky outcrops, and sometimes there are rocks of strange shapes as a result of the carving of the winds that blow them, so they are in the form of mushrooms or other things. Temporary lakes may form in the desert and then dry up completely or turn into marshes. Groundwater sources may exist there in the form of springs or seepage from aquifers from which oases are formed.
The term desert refers to relatively large areas that receive small amounts of rain. As most deserts are arid lands with dry conditions that make them unsuitable for most types of animal and plant life. Some deserts are very hot, as daytime temperatures may reach 54°C, some are characterized by cold winters, and some remain cold throughout the year.
Although many deserts are covered with sand, sand dunes cover only about 10% of the world’s deserts. Some deserts consist of mountains, others are dry expanses of rocks or sand, and some deserts embrace a variety of plants, animals, and other organisms that possess special qualities that help them live in this harsh environment.
Desert plants and animals need special adaptations in order to survive in the harsh desert environment. The plants tend to be hardy, with wiry leaves, small and sometimes leafless, with a water-resistant cuticle, and often with thorns to deter herbivores from eating them. Some annual plants germinate in the desert, flower and die within a few weeks after the rains, while other perennial plants are able to survive for several years due to their deep roots that are able to tap the moisture in the ground.
Animals need to remain cool and find enough food and water in order to survive. Many animals are nocturnal, stay in the shade, or escape to underground places during the heat of the day. Desert animals tend to be effective in conserving water, extracting most of their needs from it, and their urine is high in ammonia (concentrated) to reduce the amount of water lost through urination.
There are types of animals that are in a state of stillness for long periods, then become active when rare rains fall, so they multiply quickly, taking advantage of the presence of water before returning to a state of stillness.
Human beings have lived in deserts for thousands of years, so they moved with their herds everywhere to graze their animals, and the opportunities for oases provided a means for a more stable life.
The reclamation of semi-arid regions increases soil erosion and is one of the causes of increasing desertification. As for cultivation, it is possible if there is an irrigation system, and the Imperial Valley in California is the best guide to how to cultivate barren land by bringing water from an external source.
In the past, many trade routes passed through the deserts, especially through the Sahara Desert, and traditionally they were used by camel caravans carrying salt, gold, ivory and other goods. Large numbers of slaves were also taken north across the desert.
Some deserts have many colours as a result of containing different minerals, giving them multiple colours. Examples of such deserts are the Painted Desert (Arizona) and the Painted Desert (South Australia). Minerals are extracted from some rich deserts, and their richness in the sunlight makes them an important source for the exploitation of solar energy through solar panels.
The word desert is associated with sand dunes, extreme heat, and scorching sun rays, but deserts are not always like that, and they can be completely different from this description.
The definition does not include sand dunes or extreme heat, but rather other characteristics that are more important that it is a dry land that receives only small amounts of precipitation (less than 250 mm), or it may not rain at all. Temperatures are not a criterion for defining deserts, and the largest desert in the world is actually one of the coldest parts of our planet.
The Antarctic desert is the largest in the world, and it is not a desert that forms part of the continent’s territory, but rather the entire continent is a desert. The definition fully applies to Antarctica, located in the extreme south of the globe, which is considered one of the driest places on Earth.
Antarctica is covered with ice that contains 90% of the Earth’s freshwater, and only 2% of its area is not covered by ice. The continent receives less than 51 mm of precipitation inland, and it does not support any human life except for scientists.
The Sahara Desert in North Africa is the third largest one after Antarctica and the North Pole and the largest sand desert in the world. It covers an area of 9.4 million km2, and it extends over most of North Africa from east to west, with the exception of the coastal strip on the Mediterranean Sea.
Deserts cover about a 5th of the land area, and they, in general, are vast dry lands that receive small and scarce amounts of rain. Below is a list of the largest deserts in the world in terms of area.
| Desert | Area | |
| 1 | Antarctic | 14,000,000 km² |
| 2 | Arctic | 13,900,000 km² |
| 3 | Sahara | 9,200,000 km² |
| 4 | Great Australian | 2,700,000 km² |
| 5 | Arabian | 2,330,000 km² |
| 6 | Gobi | 1.295,000 km² |
| 7 | Kalahari | 900,000 km² |
| 8 | Patagonian | 673,000 km² |
| 9 | Syrian | 518,000 km² |
| 10 | Great Basin | 490,000 km² |
The term includes polar or icy deserts, subtropical deserts, deserts with cold winters, and cold coastal deserts. The Sahara is the largest hot desert in the world. It is a subtropical desert in North Africa. The largest on Earth is the Antarctica Desert which covers an area estimated at about 14.2 million km².
Antarctica has the lowest official temperature recorded on the planet. It is divided into East Antarctica, which consists mostly of a high plateau covered with ice, while the western part of it, most of it consists of an ice sheet covering the archipelago of mountainous islands.
The Antarctic desert is part of Antarctica which is located in the southern hemisphere and is covered by an ice sheet with a volume of about 29.6 million km² and a thickness of about 2.4 km. It is the most windswept and driest region on the planet, where the humidity is only 5%. Antarctica is classified as a large, cold and arid desert covered by thick ice by up to 98% of the land.
The largest deserts in the world are located in the polar regions of Antarctica continent, which is estimated at 5.5 million km2, which is the largest in the world. As you may know, it is located in the southern half of the continent of Antarctica, and the second type is the polar desert that extends over Several parts of Alaska, Canada, Greenland, Iceland, Norway, Sweden, Finland, and Russia, and the area of the second largest polar desert is estimated at 5.4 million square miles.
The average annual temperature in Antarctica ranges from -10°C in the coastal parts, to -60°C in the higher parts of the interior, and the summer temperature near the coast may exceed +10°C, but it may fall below -40°C in winter, and in the high interior areas the summer temperature can rise to -30°C, but it drops in winter to less than -80°C.
The lowest temperature in Antarctica was recorded in 1983 at Vostok Station. It is the lowest temperature recorded on Earth’s surface, which was -89.2°C. Most of the precipitation in Antarctica is in the form of snow or ice crystals, but rain may sometimes fall near the coast.
The average annual amount of snow accumulated above the continent is the equivalent of 150 mm of water, where the amount of snow decreases in the high areas, it does not exceed 50 mm, but it may exceed 200 mm near the coast, and the area near the Bellingshausen Sea witnesses the heaviest precipitation on the continent, with more than 1,000 mm annually.
The dry climate and low temperatures are among the most important reasons that prevent the presence of a permanent population in Antarctica, in addition to the glare of sunlight reflected from the vast areas of the ice and the problems caused by burns and difficulty in seeing, and the number of temporary residents may range between 1,000 people in the winter, to about 5,000 people in the summer.
These groups consist mainly of scientific researchers and auxiliary workers, where scientists take turns going there to study the ice, and they come from dozens of different countries to work in government-supported research stations, and in addition to scientists and researchers, tourists visit Antarctica in the summer.
Since 1969, Antarctica has become one of the most popular tourist destinations in the world. The average annual number of visitors to Antarctica has increased from several hundred to more than 34 thousand visitors, and the total number of people who visited the continent during the (2018–2019) season reached about 55,489 visitors.
All activities in Antarctica are highly regulated under the Antarctic Treaty for Environmental Protection Purposes, and these tourism activities are managed by the International Association of Antarctic Tour Operators (IAATO).
Plant life in Antarctica is limited to a few lichens, rock lichen, and algae. These plants abound in the northern and coastal regions of the continent, while they are greatly reduced in the interior regions. Seasonal algae vegetation has increased significantly over the past five decades, and it is expected Scientists believe that the cold continent will become greener as global temperatures continue to rise.
The region lacks green vegetation and is devoid of amphibians, reptiles, and mammals that live on land. However, it thrives in marine and amphibious animal life, represented by large numbers of penguins, whales, fish, and invertebrates that live along the coasts and in cold seas, especially in the summer. The ocean waters in Antarctica are among the most diverse aquatic environments on the planet, and upward water currents contribute to moving phytoplankton and algae that feed on thousands of species of marine animals, such as krill.
The types of marine mammals and whales that live in cold Antarctic waters are the Blue whale, the Fin whale, the Humpback whale, the Right whale, the Minke whale, and the Sperm whale. There are also seals, which are considered one of the most predatory marine animals. It is about 3 meters long, weighs 400 kilograms, and has long, sharp teeth that it uses to tear its prey, like fish and penguins.
The penguin is one of the most common animals in Antarctica. These birds have adapted to cold waters, where their wings act as fins that help them swim quickly in search of food, such as squid and fish, and the feathers that cover their bodies maintain their temperature in the freezing waters. It should be noted that the male emperor penguin is the only warm-blooded animal that remains on the continent during the frozen winter, where it remains in the nest and preserves the eggs laid by the female until they hatch.
The Sahara Desert was given this name in relation to the term desert in Arabic, and it is the largest sandy desert in the world and the third largest after the cold deserts of Antarctica and the Arctic. It extends to more than 4.8 thousand km along the African continent, and its lands extend at a distance of 1.9 km south to Central Africa and cover a total area of 9 million km2 or nearly a third of the African continent.
The Atlantic Ocean borders the Sahara from the west, the Red Sea from the east, the Mediterranean Sea from the north, and the Savannah coast from the south. The Sahara extends over the lands of eleven countries: Algeria, Egypt, Chad, Libya, Morocco, Tunisia, Sudan, Mali, Mauritania, Niger, and Western Sahara, despite the scarcity of water there.
However, it contains two permanent rivers, namely: the Nile River and the Niger River, and there are at least 20 seasonal lakes and underground water basins on its lands, which are a major source of water for more than 90 desert oases.
The Sahara is affected by two types of climate systems, a northern one and a southern one, where the climate in the north is semi-tropical and dry, and the annual rates of temperatures are high, with an average of 20°C, and the winters there are cold to moderately cold, and the summers are hot, and there is a maximum of two precipitations, and this climate results from the stability of the high-pressure chambers that are centred above the Tropic of Cancer.
As for the south, the climate is dry tropical, characterized by a high temperature due to the change in the inclination angle of the sun, so the winters are mild and dry, and the summers are dry and hot with variable precipitation, and the temperature is moderate and relatively constant along the narrow strip of the coastal region due to the influence of the cold Canary Current.
The average monthly temperatures for the entire region during the cold season are around 13°C, and temperatures can exceed 50°C during the hottest months, and the highest temperature ever recorded was 58°C in Al-Azizia in Libya. Temperatures during the day in the summer and winter months and the amounts of precipitation are also variable, with an annual average of about 76 mm. Most of the rain falls between December and March.
Deserts expand during the dry seasons, and their area usually decreases during the rainy season. However, a study published in 2018 in the Journal of Climate showed that the area of the Sahara has increased by approximately 10% since 1920. The change in the human-caused climate led to an increase in the desert’s breadth, and the study’s authors estimated that nearly a third of the expansion in the desert was due to human-caused climate change.
Man has inhabited the Sahara for 6,000 years BCE and earlier. Egyptians, Phoenicians, Greeks and Europeans were the first to inhabit it, and today the population of the Sahara is about 4 million people, the majority of whom are residents of Algeria, Egypt, Libya, Mauritania, and Western Sahara.
Most of the people who live in the desert today are Bedouins who move from one area to another. Therefore, there are many different nationalities and languages along the Sahara, but the Arabic language remains the most widespread language. As for the permanent residents of cities, villages and fertile oases. They are famous for agriculture and mining, such as iron mining in Algeria and Mauritania and copper mining in Mauritania, which contributed to the population growth in the region.
The Sahara is home to many plants and animals despite the dry and harsh conditions, where there live about 500 species of plants and 70 species of mammals, 20 of which are large mammals such as the spotted hyena.
Other mammals, such as the jerboa and the sand fox, and there are 90 species of birds, and 100 species of reptiles, such as snakes and lizards, and even crocodiles that are found in Places where there is enough water, in addition to many spiders, scorpions and other small arthropods, such as dung beetle, scarab beetle, yellow scorpions, and many species of ants.
Camels are among the most famous animals in the desert. They are originally from North America, and they travelled across the Bering Strait 3 to 5 million years ago. Camels navigate the desert because of its characteristics that make them suitable for a hot and dry environment. It stores fat in the hump on its back and uses it between meals to obtain energy and hydration. This process is done with high efficiency so that camels can last for more than a week without water and remain for several months without food.
The most arid regions of the desert are completely bare and empty of plant life, and there are drought-resistant plants that have adapted to arid conditions, and some of them have adapted to saline conditions called halophytes. As most of them have extended roots that reach deep into the ground in search of deep water, and some have left in the form of thorns to reduce the loss of moisture, and there are also plants that live in oases areas such as the Nile Valley, which abound in olive trees, palm trees, and various shrubs and herbs.
If you enjoyed this article why not check out some more Geography Facts and Topics: Mountains, Rainbows, Hurricanes, Thunderstorms, Islands, Blizzards, Volcanoes and Continents.
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