Covering the majority of northern Africa, the Sahara is the world’s most famous desert. But how much do you really know about this iconic landscape? Let's delve into some fascinating facts about this vast and diverse region.
The Sahara Desert as seen from space.
Size and Location
The Sahara spans nearly a third of the African continent, reaching a total of 11 countries. These include large parts of Algeria, Chad, Egypt, Libya, Mali, Mauritania, Niger, Western Sahara, and Sudan, as well as parts of southern Morocco and Tunisia.
The Sahara Desert spans some 8,600,000 square kilometers. Scientists estimate that the Sahara’s overall size has grown to be 10% larger than it was nearly a century ago.
It stretches from the Red Sea in the east and the Mediterranean in the north to the Atlantic Ocean in the west, where the landscape gradually changes from desert to coastal plains. To the south it is bounded by the Sahel, a belt of semi-arid tropical savanna around the Niger River valley and the Sudan region of sub-Saharan Africa.
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The Sahara covers 9 million square kilometers (3,500,000 sq mi), 31% of the African continent. If all areas with a mean annual precipitation of less than 250 mm (9.8 in) were included, the Sahara would be 11 million square kilometers (4,200,000 sq mi). It is one of three distinct physiographic provinces of the African massive physiographic division.
Several deeply dissected mountains, many volcanic, rise from the desert, including the Aïr Mountains, Ahaggar Mountains, Saharan Atlas, Tibesti Mountains, Adrar des Iforas, and the Red Sea Hills.
Misconceptions and True Size
It’s a common misconception that the Sahara is the world’s largest desert. In actual fact, it’s the largest hot desert behind the Arctic and Antarctica, which are both cold deserts.
Landscape
Sand dunes and sheets cover only around 25% of the Sahara’s actual surface. The principal topographical features of the Sahara include shallow, seasonally inundated basins (chotts and dayas) and large oasis depressions; extensive gravel-covered plains (serirs or regs); rock-strewn plateaus (hammadas); abrupt mountains; and sand sheets, dunes, and sand seas (ergs).
The serirs and regs differ in character in various regions of the desert but are believed to represent Cenozoic depositional surfaces. A prominent feature of the plains is the dark patina of ferromanganese compounds, called desert varnish, that forms on the surfaces of weathered rocks.
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The plateaus of the Sahara, such as the Tademaït Plateau of Algeria, are typically covered with angular, weathered rock.
In the central Sahara, the monotony of the plains and plateaus is broken by prominent volcanic massifs-including Mount ʿUwaynat and the Tibesti and Ahaggar mountains.
Sand sheets and dunes cover approximately 25 percent of the Sahara’s surface. The principal types of dunes include tied dunes, which form in the lee of hills or other obstacles; parabolic blowout dunes; crescent-shaped barchans and transverse dunes; longitudinal seifs; and the massive, complex forms associated with sand seas.
Several pyramidal dunes in the Sahara attain heights of nearly 500 feet, while draa, the mountainous sand ridges that dominate the ergs, are said to reach 1,000 feet. An unusual phenomenon associated with desert sands is their “singing” or booming.
Climate
The Sahara exhibits great climatic variability within its borders, with two major climatic regimes differentiating along a north-south axis: the desert’s northern latitudes are arid subtropical and have two rainy seasons, while the southern ones, although also arid, are more tropical and have only one rainy season. The southern reaches of the Sahara end in the Sahel, a semiarid buffer zone that separates the desert from the more temperate savanna biomes beyond.
Read also: Unveiling Sub-Saharan Africa
The central Sahara is hyperarid, with sparse vegetation. The northern and southern reaches of the desert, along with the highlands, have areas of sparse grassland and desert shrub, with trees and taller shrubs in wadis, where moisture collects.
The permanent absence of clouds allows unhindered light and thermal radiation. The stability of the atmosphere above the desert prevents any convective overturning, thus making rainfall virtually non-existent.
The prevailing air mass lying above the Sahara is the continental tropical (cT) air mass, which is hot and dry. Hot, dry air masses primarily form over the North-African desert from the heating of the vast continental land area, and it affects the whole desert during most of the year.
Also, to be protected against rain-bearing weather systems by the atmospheric circulation itself, the desert is made even drier by its geographical configuration and location. The Atlas Mountains of Algeria, Morocco and Tunisia also help to enhance the aridity of the northern part of the desert.
The primary source of rain in the Sahara is the Intertropical Convergence Zone, a continuous belt of low-pressure systems near the equator which bring the brief, short and irregular rainy season to the Sahel and southern Sahara.
The sky is usually clear above the desert, and the sunshine duration is extremely high everywhere in the Sahara. Most of the desert has more than 3,600 hours of bright sunshine per year (over 82% of daylight hours), and a wide area in the eastern part has over 4,000 hours of bright sunshine per year (over 91% of daylight hours).
The high position of the Sun, the extremely low relative humidity, and the lack of vegetation and rainfall make the Great Desert the hottest large region in the world, and the hottest place on Earth during summer in some spots.
The average high temperature exceeds 38 to 40 °C (100.4 to 104.0 °F) during the hottest month nearly everywhere in the desert except at very high altitudes. There are even hotter spots in the Sahara, but they are located in extremely remote areas, especially in the Azalai, lying in northern Mali.
The major part of the desert experiences around three to five months when the average high exceeds 40 °C (104 °F); while in the southern central part of the desert, there are up to six or seven months when the average high temperature exceeds 40 °C (104 °F).
The annual average daily temperature exceeds 20 °C (68 °F) everywhere and can approach 30 °C (86 °F) in the hottest regions year-round.
Due to lack of cloud cover and very low humidity, the desert usually has high diurnal temperature variations between days and nights. On average, nighttime temperatures tend to be 13-20 °C (23-36 °F) cooler than in the daytime.
The average annual rainfall ranges from very low in the northern and southern fringes of the desert to nearly non-existent over the central and the eastern part. The vast central hyper-arid core of the desert is virtually never affected by northerly or southerly atmospheric disturbances and permanently remains under the influence of the strongest anticyclonic weather regime, and the annual average rainfall can drop to less than 1 millimetre (0.04 in).
Climate Data of Select Locations in the Sahara Desert
| Location | Average High Temperature (Hottest Month) | Annual Average Rainfall | Sunshine Hours Per Year |
|---|---|---|---|
| Adrar, Algeria | 46 °C (114.8 °F) | Very Low | > 3600 |
| Bilma, Niger | > 40 °C (104 °F) for 6-7 months | Low | > 3600 |
| Aswan, Egypt | > 40 °C (104 °F) | ~0.5 mm | > 4000 |
Historical Climate Variations
One theory for the formation of the Sahara is that the monsoon in Northern Africa was weakened because of glaciation during the Quaternary period, starting two or three million years ago.
The climate of the Sahara has undergone enormous variations between wet and dry over the last few hundred thousand years. At present, it is in a dry period, but it is expected that the Sahara will become green again in 15,000 years.
During the last glacial period, the Sahara was much larger than it is today, extending south beyond its current boundaries.
Once the ice sheets were gone, the northern Sahara dried out. In the southern Sahara, the drying trend was initially counteracted by the monsoon, which brought rain further north than it does today.
Ecoregions
The Sahara comprises several distinct ecoregions. The Atlantic coastal desert is a narrow strip along the Atlantic coast where fog generated offshore by the cool Canary Current provides sufficient moisture to sustain a variety of lichens, succulents, and shrubs.
The North Saharan steppe and woodlands is along the northern desert, next to the Mediterranean forests, woodlands, and scrub ecoregions of the northern Maghreb and Cyrenaica.
Adaptations of Life in the Sahara
Despite these harsh living conditions, the Sahara desert isn’t a lifeless wasteland.
Though boasting an extremely low primary productivity, the Sahara does manage to support some life. Many of the organisms that can survive have been able to do so with adaptations for arid environments: for example, many herbaceous plants found in the Sahara are ephemerals, meaning that almost all of their life cycle-from germination to seed dispersal-occurs in the two- to three-week period after a heavy rain. Animals such as the desert snail survive by using estivation, a period of dormancy that some animals can enter when encountering extreme environmental stress.
Despite how difficult living in the Sahara desert is, various plants and animals have adapted to these conditions. Some also have the added ability to tolerate highly salty environments (halophytes). One of the most prominent plants in the Sahara desert is the date palm, which grows as tall as 69 to 75 feet (21 to 23 meters).
Most people associate camels with the Sahara desert, and they’re right. Some interesting animals in this region are the deathstalker scorpion, desert crocodile, African silverbill, hyrax, and African wild dog.
A Fennec Fox, one of the many animals adapted to life in the Sahara Desert.
It may be one of the harshest environments on Earth, but the Sahara is home to a variety of wildlife that has adapted to a life of extremes. Alongside camels and goats, desert species include cheetah, gazelles, ostrich, Fennec fox and monitor lizards.
People of the Sahara
Around 2.5 million people also call the Sahara home, most of which have Berber or Arabic roots. People have lived in the Sahara long before recorded history, at certain times in regions that are now too arid for human inhabitance.
Archaeological findings indicate that there were once ancient Saharan lakes, upon the shores of which humans lived, hunted, and fished. Even after these lakes ceased to exist, humans survived for centuries in the desert using alternative methods: nomadic pastoralists herded goats, sheep, or camels to whatever pasturage could be found; sedentary agriculturalists, confined to oases, harnessed their limited water resources to grow crops such as date palms and barley; and specialists (for example, blacksmiths) traded wares with their agriculturalist and pastoralist neighbors. Certain groups have long relied on traveling and trading along caravan routes to obtain their livelihood, journeying by camel to oases and population centers all over the Sahara.
The Sahara desert is home to about 2.5 million people, usually clustered around the few scattered areas that can support plant and animal life. Many tribes living in the Sahara desert practice the nomadic lifestyle that involves traveling from one place to another. The Tuaregs are probably one of the most well-known nomadic tribes in this region, but they’re not the only ones.
People in the Sahara desert wear loose-fitting clothes to deal with the heat. This prevents the rapid evaporation of sweat to reduce water loss. They’ve adapted their clothing and lifestyle to fit this unique environment.
Saharan Trade Routes
Saharan trade routes played an important part in the economies of Ancient Africa. Goods such as copper, salt and gold were transporting using camel caravans, which in their heyday consisted of thousands of camels.
Modern Economy
After World War II, prospecting revealed that the Sahara was laden with oil and mineral resources, which have served as a major attractor of international investment since. Oil, natural gas, and coal reserves have been discovered all over northern Africa and particularly have been exploited by various countries, such as Egypt, Libya, and Algeria.
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