A desert is defined as an area that does not receive a high amount of annual precipitation, resulting in the inability for plant and animal life to thrive on its ground. A common misconception about deserts is that they are always hot, sandy, dry areas. This is not, however, the case. Deserts can be cold as well. For example, Antarctica is the world’s largest cold desert. Its enormity is also the reason that almost 20% of the earth’s landmasses are classified as deserts.
1. Hot deserts are not only extremely hot during the day, but they can be extremely cold at night
Hot and dry deserts are, on average, between 68 and 77 degrees Fahrenheit. This is because during the hottest part of the day, the temperature can increase to 120 degrees Fahrenheit, and at night the temperature can drop to only 35 degrees Fahrenheit.
2. Although infrequent, when it rains in the desert, it pours
To be classified as a desert, an area must receive less than 19.75 inches of rain annually. Hot or arid deserts typically have only short episodes of rain between months of dry periods with no rain. This rain typically evaporates shortly after it falls to the ground. The Atacama Desert in Chile records the lowest average rainfall, at less than .75 inches of rain annually.
Cold deserts typically receive a decent amount of snow. Average precipitation amounts are around seven to ten inches annually. Depending on the climate, rainfall occurs primarily in autumn.
3. The Joshua tree is one of the only tree varieties that grows in the desert
The Joshua tree, named by a ground of Mormons that explored the Mohave Desert, is one of the most notable North American desert trees. Its trunk is a cluster of thousands of fibers (unlike typical hard wood trees with growth rings), which hold on to the little water that they receive annually. The branches of the tree are located only at the top canopy of the trunk and provide a solid shadow, with very little sun making its way through the dense vegetation. The trees roots can grow between 30 and 50 feet from the trunk of the tree, giving it stability and the ability to seek out water to channel up the tree’s trunk. The tree produces flowers and fruit annually from February until April.
4. Camels store fat (not water) in their humps
Children are often taught that camels carry water in the hump or humps on their backs so that they can survive for days without water in the hot dry deserts where they are sometimes found. This is, however, misinformation. The humps on camel’s backs are actually storage areas for body fat. This extra body fat is conveniently located out of the way so as not to impede the camel’s function, but it becomes vitally important if the animal finds itself unable to drink or eat for days or even weeks. The fatty tissue is slowly used by the body for energy during these times.
5. Deserts cover 20% of the Earth’s surface
Much of this surface area is due to the enormous Antarctic Desert, which measures 5,400,000 square miles. The Arctic Desert contributes the next largest percentage, covering 5,300,000 square miles and including parts of Alaska, Canada, Greenland, Iceland and Russia. The Sahara Desert is the third and last desert that measures over one million square miles, and occupies 3,320,000 square miles in northern Africa.
6. The Sahara desert is the world’s largest hot desert
The desert is located in northern Africa and covers 10% of the continent, an area of more than 3 million square miles. Its area is almost as large as the whole of Europe. Not many species are able to inhabit the Sahara, but those that are have adapted to survive the harsh conditions.
As recently as about 5000 years ago, the desert had significantly more water and vegetation that it does today. It is not clean why the change has taken place over these millennia, but today the Sahara is one of the hottest and driest areas in the world.
7. Antarctica is the world’s largest cold desert
Antarctica is the coldest, dried and windiest continent in the world and due to its extreme lack of precipitation (less than 10 inches annually) is classified as a cold desert. The snow and ice located there has been intact for thousands of years and remains intact during the warm months because temperatures do not increase for long enough periods of time to create any significant melting. Because of its temperatures and lack of water supply, living organisms have a hard time surviving these conditions and the land is home to only a few select species of animals and vegetation.
8. An oasis is typically caused by low desert elevations that result in underground springs
An oasis is defined as an area located within a desert that has fertile ground and may contain pools of fresh water. These locations have water because they are typically located in valleys of deserts that lie below the water table. The water table in a desert is lower than it is in areas that typically support vegetation and animal life, however there is still an elevation in a desert where water lies below the surface of the ground. When an area lies beneath this elevation mark, the water comes from underground springs through the sand, creating pools of life-supporting water. Towns and small villages build their homes around desert oases and use its water to survive. Occasionally, an oasis will be formed by a large sandstorm, which blows thousands of tons of sand to a new location, leaving behind an area that may be exposed to the water table. Quick planting of seeds in these areas can lead to the growth of plants and trees and the formation of an oasis.
9. Sand dunes, called ergs, make up only a very small amount of desert surface area
These sand dunes have become the iconic picture of a desert. While they do occur in deserts, the land is primarily made up of rocky hard surfaces. The dunes are formed when an object causes sand blowing in the wind to wrap around it and stop on the opposite side, when the wind speed is zero. They grow from very small beginnings, to become enormous swaths of land, hundreds of feet deep in some areas.
The name “erg”, as it is called in English, means “artery” in Arabic and describes the shape that these land masses begin to take after forming.
10. North America is home to the world’s tenth largest desert, the Great Basin Desert
The Great Basin Desert is located to the west of the Rocky Mountains and to the east of the Sierra Nevadas, occupying a large percentage of Nevada, and smaller areas in California, Idaho and Utah. To its south lie the Mojave and Sonoran deserts. The elevation of the Great Basin Desert lies between 3,000 and 6,500 feet, and as a result is classified as a cold desert. The annual rainfall averages between 7 and 12 inches, much of it falling as snow in the winter season.
20 Largest Deserts in the World
Sahara Desert (Africa)
Arabian Desert (Arabia)
Gobi Desert (China)
Patagonian Desert (Argentina)
Rub’al Khali Desert (south Arabia)
Great Victoria Desert (Australia)
Kalahari Desert (Africa)
Great Basin Desert (Nevada)
Chihuahuan Desert (Mexico)
Thar Desert (India/ Pakistan)
Great Sandy Desert (Australia)
Kara-Kum Desert (W. Asia)
Colorado Desert (USA)
Gibson Desert (Australia)
Sonoran Desert (USA)
Taklamakan Desert (China)
Iranian Desert (Iran)
Simpson/ Sturt Desert (Australia)
Atacama Desert (Chile)
Mojave Desert (USA)