Hot deserts mainly form near the equator due to descending dry air and high atmospheric pressures, while cold deserts are found near the poles due to the lack of heat from the sun and cold winds coming from polar regions.
Hot deserts like the Sahara or Kalahari are mainly found around latitudes close to the tropics, where the sun beats down heavily all year round. These regions rarely see rain due to a particular atmospheric circulation that will be discussed in more detail shortly.
Cold deserts, on the contrary, are often located in areas far from the equator or at high altitudes. For example, the Gobi desert, located in Central Asia, experiences frigid winters despite its scorching summers. The Antarctic, on the other hand, is an extreme cold desert: it receives very little precipitation, but this falls exclusively as snow, covering a continent that is already frozen.
In any case, whether hot or cold, deserts primarily appear where water is painfully scarce all year round. Their locations are not random, far from it: they follow very precise logics influenced by the atmosphere, the ocean, the positioning of continents, and mountain ranges.
On Earth, some regions naturally receive much more solar energy than others. Near the equator, solar radiation strikes the surface directly, resulting in high temperatures. This warm air rises because it has become less dense: imagine a hot air balloon ascending into the sky; the mechanism is similar. As it gains altitude, this humid air gradually cools and releases its moisture in the form of rain around the equator (hence the lush tropical forests). Now drier, this air continues to circulate in the upper atmosphere towards the tropics, descending back to the surface around the latitudes of 30° north and south, creating high-pressure zones called Hadley cells. This is where the famous hot deserts, like the Sahara or the Australian desert, are located, where the dry air absorbs any trace of residual moisture on the ground, greatly limiting precipitation.
Conversely, towards the poles, where the frigid air is already very dry and cold, polar cells form. This cold air circulates while remaining close to the Earth's surface, resulting in almost no precipitation—leading to cold deserts, like that of Antarctica. These large atmospheric mechanisms explain how such distant regions can both lack water, but for completely opposite reasons.
Hot or cold deserts depend heavily on the ocean currents that run along their coasts. When these currents come from the poles, they bring very cold water: this also cools the air above, making it dry because cold air holds little moisture. The result is no rain! This is typical of the Western Sahara desert, near the cold Canary current. Conversely, when a warm current flows near the coast, it can bring warm, humid air, but if this air cannot penetrate far enough inland, it also leaves a parched landscape in the interior of the continent. Currents therefore play a very concrete role: they influence temperatures, air humidity, and ultimately the presence or absence of precipitation.
When altitude rises, temperatures drop: that's why some deserts located in the mountains are cold deserts. Even though the air remains very dry, the height makes the atmosphere much cooler. At night, up there, temperatures fall sharply, sometimes well below zero. This is exactly the case in Tibet or the Andes, where the sun beats down hard during the day, but as soon as it disappears, everything cools down quickly due to the thin air that holds heat poorly. In contrast, deserts at sea level accumulate heat more easily and often maintain scorching temperatures even after sunset. At high altitude, atmospheric pressure decreases, which reduces the air's ability to store and transport moisture, further exacerbating their aridity.
Mountain ranges clearly alter precipitation: the mountains block moisture from winds coming off the sea, creating a dry area known as a rain shadow behind them. This is exactly how the Mojave Desert formed behind the Sierra Nevada mountains in California.
Similarly, a location deep within a continent can make it difficult for humid air from the oceans to arrive. The result is persistent drought and therefore a very continental desert, as is the case with the Gobi Desert, located inland in Central Asia.
The soil also plays a significant role: rocky or sandy soils retain less water, reducing the amount of moisture available in the air. This significantly fosters the creation of deserts.
There are plant species specially adapted to deserts, such as the Welwitschia in Namibia, which can survive for several centuries with only a few drops of water per year.
The Atacama Desert in Chile is one of the driest deserts on the planet. Some areas have not seen significant rainfall for hundreds of years.
Some hot deserts experience drastic temperature drops at night, with differences exceeding 30°C between day and night, due to the low humidity levels in the air.
The highest temperature ever recorded on Earth was noted at Furnace Creek in Death Valley, California, reaching 56.7°C in 1913.
No, contrary to a common misconception, not all deserts are exclusively made up of sand. Many deserts, especially cold deserts, are primarily composed of stones, gravel, or even ice, like Antarctica, which is considered the largest cold desert in the world.
Yes, there are deserts with marked seasonal climatic contrasts. Some subtropical deserts, like the Gobi Desert in Central Asia, experience both very hot summers and cold winters, exhibiting a particularly high annual temperature range.
Cold deserts are home to animals that have adapted to extreme cold and a lack of regular food, such as the polar bear, the arctic fox, certain migratory birds, as well as more modest mammals like lemmings and arctic hares.
Desert regions are generally located in areas dominated by high atmospheric pressure, where dry air descends from the upper atmosphere, preventing cloud formation. Atmospheric circulation and mountain barriers also contribute to reducing precipitation.
Cold marine currents cool the air that passes over them, reducing the air's capacity to hold water vapor. Thus, when it reaches the coast, the air is dry and creates a desert climate, as is the case with the cold Humboldt current responsible for the Atacama Desert in Chile.
The main difference lies in their average annual temperature. Hot deserts experience high temperatures throughout the year, with very hot days and often cool nights, while cold deserts endure extremely low temperatures, with harsh winters and often short, cool summers.
0% of respondents passed this quiz completely!
Question 1/5
