The Sahara Desert is the largest hot desert in the world. Let's explore this intriguing and beautiful place in this lesson.
The Sahara is one of the harshest environments on Earth, covering 3.6 million square miles (9.4 million square kilometers), nearly a third of the African continent, about the size of the United States (including Alaska and Hawaii). Only the two cold deserts, Antarctica and Arctic deserts are bigger than the Sahara.
The name of the desert comes from the Arabic word ṣaḥrāʾ, which means "desert."
The Sahara Desert is located in North Africa.
The Sahara covers large sections of eleven different countries including Egypt, Libya, Tunisia, Algeria, Morocco, Western Sahara, Mauritania, Mali, Niger, Chad, and Sudan.
You might think that the Sahara Desert is the driest place on the Earth. But you are WRONG!
Surprisingly, the hottest and driest deserts are cold, not hot. That’s because cold air holds 20 times less water vapor than hot air. In this regard, while the Atacama Desert in Chile is the driest warm desert on Earth, the McMurdo Dry Valleys in Antarctica (cold polar desert) are even drier.
Today, the Sahara Desert is defined by undulating sand dunes, unforgiving sun, and oppressive heat but once it was a lush green forest. Its climate hasn't always been arid. It is thought that between 5,000 and 11,000 years ago there was green vegetation, abundant wildlife and numerous bodies of water in the area. Scientists call this period the African Humid Period. So where did all that water go?
Scientists believe this transition from green to desert occurred due to a slow change in the Earth's orbit and lesser rainfall which triggered humans to domesticate animals like cattle, goats and sheep. This led to overgrazing and wearing away of the soil.
Landscape
When you think of the Sahara Desert, what is the first picture that comes to your mind? That of large sand dunes, isn't it?
Well, sand dunes are the postcard image of the Sahara. Around 25% of the desert is sand dunes, some of which reach over 500 ft (152 m) in height.
Most of the Sahara Desert is undeveloped and has varied topographic features including sand dunes, sand seas called ergs, barren stone plateaus, gravel plains, dry valleys and salt flats.
Let's take a look at some of the different types of landscapes in the Sahara Desert.
| Dunes | These are hills made of sand. |
| Ergs |
These are large areas of sand. They are sometimes called sand seas. |
| Regs | These are flat plains covered with sand, stones and pebbles. |
| Hamada |
These are hard and barren elevated plateaus, which look a lot like the Reg. |
| Wadi | These are the beds of rivers or streams. almost always dry, they form plains dotted with a few trees. |
| Oasis |
This is an area made fertile by a source of freshwater in an otherwise dry and arid region. Communities have traditionally planted strong trees, such as palms, around the perimeter of oases to keep the desert sands from their delicate crops and water. |
Its highest point is Chad's Mount Koussi (an extinct volcanic crater that rises 11,204 feet above sea level at the peak), and its lowest, Egypt's Qattera Depression (an oasis depression that lies 436 feet below sea level at the deepest point).
Although water is scarce across the entire region, the Sahara contains two permanent rivers (the Nile and the Niger), at least 20 seasonal lakes and huge aquifers, which are the primary sources of water in the more than 90 major desert oases.
*aquifer is a body of porous rock or sediment saturated with groundwater.
Climate
The Sahara has one of the world's most severe climates. Typically, the Sahara landscape experiences extremely limited to virtually no rainfall, powerful and capricious winds and wide temperature ranges.
Across the desert, the annual average rainfall equals no more than a few inches or less, much less in many locations. In some areas, no rain at all may fall over several years. Then, several inches may fall in a torrential downpour. Then, no rain at all may fall for several more years.
The Sahara Desert has extremely long daylight hours, very little cloud formation, and very low humidity.
Plants and Animals
Due to the high temperatures and arid conditions of the Sahara Desert, the plant life in the Sahara Desert is sparse with the highest concentrations occurring along the northern and southern margins and near the oases and drainages. Plants that grow in the Sahara Desert have adapted to heat, drought and salty conditions of the desert. For example, plants such as date palms and acacia grow near wadis and oases, where they put down long roots to reach life-sustaining water. Another example is flowering plants that grow in arid areas - the seeds of these flowering plants sprout quickly after a rain, putting down shallow roots, and completing their growing cycle and producing seeds within a few days before the soil dries out. The new seeds may lie dormant in the dry soil for years, awaiting the next rainfall to repeat the cycle.
Just like the plants, animals in the Sahara Desert have adapted to the harsh environment. For example, in the heart of the Sahara, most mammals are relatively small, which helps to minimize water loss. They meet their water needs from their diets. They take refuge in burrows during the day, hunting and foraging primarily at night, when temperatures are lower. They have also developed anatomical adaptations such as the fennec fox's large ears, which help dissipate heat, and its hairy soles, which protect its feet. Other mammals include the gerbil, spotted hyena, sand fox, and Cape hare. Reptiles like the sand viper and the monitor lizard are present in the Sahara as well.
The most famous animal of the Sahara is dromedary camel, which is long used by the desert nomads. It can travel for several days without food or water. This is made possible by its physiological adaptations:
People and lifestyle
Most parts of the Sahara are uninhabited, but some people manage to survive in places where there is water. The majority of the people live in Algeria, Egypt, Libya, Mauritania, and Western Sahara.
Most people of the Sahara have genetic ancestry to three groups: Berbers, Arabs, and Sudanese.
Basically, there are three kinds of cultures within the Sahara desert:
| Pastoralists | They do not live continually in the same place but move cyclically or periodically. They move herds of cattle or camels between watering holes. Some are also merchants who move from town to town. |
| Sedentary agriculturalists | These peoples live in one place all year round, practice agriculture, and are sustained by the rare large water supplies that can be found in often fought-over oases. |
| Specialists | They practice various crafts like blacksmiths associated with herders and cultivators. |
Most of the people living in the Sahara today do not live in cities; instead, they are nomads who move from region to region throughout the desert. Because of this, there are many different nationalities and languages in the region but Arabic is the most widely spoken.
Economic activity
Livestock herding and trade are the main economic activities of the Sahara. There are huge amounts of natural resources hidden beneath the Sahara Desert. Major among these are oil and natural gas in Algeria and Libya, iron ore in Algeria and Mauritania, and phosphates in Morocco. Tourism is also a source of income for the Saharan countries and contributes to their economic growth.
Environmental effects
We may think that global warming won't have much effect on this hot desert. But surprisingly, small changes in temperature or precipitation can drastically impact the desert's biodiversity. Higher temperatures result in an increasing number of wildfires which alters the landscape of the region. Other human activities like excessive grazing by animals, mining, and oil and gas production also impacts the desert habitat. Desert is also used as nuclear testing grounds which may disrupt sensitive habitat.
