This is the Sahara Desert.
The Sahara Desert in North Africa is the world’s largest and most extensive hot desert. The term for “desert” in Arabic is ar. After Antarctica and the Arctic, it is the world’s third largest desert. Nearly a third of Africa is covered by the desert, making it about the size of the continental United States with Alaska and Hawaii included.
Countries that the Sahara Desert extends into and their locations.
The Red Sea lies between the Sahara Desert and the Atlantic Ocean to the west, the Mediterranean Sea to the north, and the semiarid tropical savannah of Sudan and the Valley of the River Niger in Sub-Saharan Africa to the south.
A total of eleven countries—Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Western Sahara, Sudan, and Tunisia—are home to various parts of this enormous desert.
Mountains, sand-dunes (erg), plateaus, barren stone plateaus (hamada), sand seas (ergs), sand-and-gravel-covered plains (reg), basins, salt flats, arid valleys (wadis), and depressions are only some of the landforms that the Sahara’s wind has carved over time.
The volcanic mountain ranges experience higher precipitation and cooler temperatures than the surrounding lowlands. Mount Koussi, an extinct volcano in northern Chad and the highest peak in the Sahara Desert at 11,204 feet (3,415 meters), is a member of the Tibesti Range. Located in Egypt, the Qattara Depression is 436 feet (133 meters) below sea level, making it the lowest point in the Sahara.
However, the sand dune fields seen in movies are what really make the Sahara renowned. Only around 15% of the desert is covered by the dunes, yet they can be as high as 600 feet (183 meters).
Over the entirety of the desert, water is in short supply. There are, however, at least 20 seasonal lakes, massive subterranean reservoirs or aquifers, and the Nile and Niger rivers, both of which run year-round. The Nile starts in central Africa and travels north through Sudan and Egypt before emptying into the Mediterranean Sea. The 90 or so large desert oasis communities rely on these for their water supply.
Authorities in charge of water management had worried that aquifers might dry up owing to misuse. However, a 2013 study published in the journal Geophysical Research Letters found that rain and runoff were still feeding the “fossil” (non-renewable) aquifers.
Sahara Climate and Humidity
The Sahara desert is the hottest substantial land region on Earth. There are two main types of climate in the Sahara: a dry subtropical climate in the north and a dry tropical climate in the south. Dry subtropical climates are characterized by extreme yearly and diurnal temperature swings, warm summers and cold to cold winters, and two precipitation maxima.
Dry, warm winters and a hot, dry season before to the changeable summer rains characterize the dry tropical climate, which follows the sun’s declination with its powerful annual temperature cycle.
Weather conditions are extremely hot and dry. Except at very high altitudes, daytime highs during the summer tend to hover around 100.4F and 104.0F (over 38 degrees Celsius). Aziziyah, Libya has the highest recorded temperature in the Sahara desert at 136 °F (58 °C).
The low-pressure systems that move through the Mediterranean Sea along the polar front bring winter clouds and modest yearly rainfall of between 4 and 10 inches to the northern edges of the Sahara. The Moroccan city of Ouarzazate and the Algerian city of Biskra are two of the few places in this zone.
The Intertropical Convergence Zone (ITCZ) brings summer clouds to the arid region bordering the Sahel, resulting in yearly precipitation of 4 to 10 inches. The area encompasses both Agadez, Niger, and Timbuktu, Mali.
The majority of the central Sahara, which is largely untouched by either the southerly or the northern atmospheric variation, receives almost no rainfall. Anticyclonic weather patterns have a continuous effect on it. The typical annual rainfall in this area is around 0.04 inches.
Amazingly, every 20,000 years or so the Sahara goes through a cycle where it is a dry, hostile desert and then it becomes a lush, green oasis, according to a study published in 2019 in the journal Science Advances. The authors of the study looked at dust deposits from the Sahara that have been accumulating in marine sediments for the past 240,000 years.
Researchers discovered that the periodic drying out and greening of the Sahara is driven in part by variations in Earth’s axial tilt, which also affects the strength of the monsoons. The monsoon rains and subsequent lush green scenery in the Sahara were made possible by the Earth’s axis tilting about one degree closer to the sun in the Northern Hemisphere, at roughly 24.5 degrees instead of the current 23.5 degrees. More sunlight meant more monsoon rains, which in turn kept the Sahara’s vegetation alive.
Prehistoric cave and rock art, as well as other archeological remains, provide insight into the Sahara’s past greenery. Fragments of pottery found in what is now a desert provide evidence that prehistoric herders farmed the area some 7,000 years ago.
For the past two thousand years, the Sahara has had a climate that is remarkably consistent. The air over the desert is dried out by the ferocious and erratic northeast winds, which also push hot air toward the equator. Due to the high velocity of these winds, significant dust storms are generated, reducing visibility to nil in the area. Dust from the Sahara can be carried by trade winds all the way to the other side of the world.
Affects of Climate Change on the Sahara
A 2018 study published in the Journal of Climate found that the extent of the Sahara desert had increased by around 10% since 1920. Similar to the Sahara, all deserts tend to expand during the dry season and contract during the rainy. But man-made climate change disrupts the normal climate cycle, leading to a larger and less frequently contracting Sahara. The researchers estimated that anthropogenic climate change was responsible for around a third of the desert’s growth.
Large-scale installations of wind and solar farms in the Sahara are the best strategy to reduce global warming’s destructive impacts. These renewable energy farms, powered by the wind and sun, would not only reduce emissions of harmful gases but also power thousands of homes. According to research published in Science Advances in 2018, it might also contribute to localized rainfall increases.
Models of wind farms have shown that they can increase local temperatures, particularly at night by bringing warm air from higher in the atmosphere down to the ground. The researchers predicted that the average rainfall over the wind farms would double, leading to a 20% increase in plant life. The outcomes of the solar farm simulations were likewise comparable.
According to the study authors, a large-scale wind farm in the Sahara would generate around 3 terawatts of electrical power, while a large-scale solar farm in the Sahara would generate around 79 terawatts, greatly exceeding the 18 terawatts of electrical power consumed in 2017. More extensive uses of the extra energy thus generated are possible, such as expanding agricultural production and desalinating more water.