Sahara | Can’t Sleep? Explore An Ocean Of Sand

The Sahara stretches across much of North Africa and is the largest hot desert in the world. This episode explores the geography of the Sahara, its vast landscapes, the people who have lived and traveled across it, and how the desert has changed over thousands of years. Along the way, you’ll hear about massive dunes, ancient trade routes, desert oases, and the surprisingly varied environments found across this enormous region.
It’s steady and consistent, with no whispering and no sudden changes, just enough to give your mind something to follow as you wind down. Happy sleeping!

Transcript

Welcome to the I Can't Sleep Podcast, Where I help you drift off one fact at a time. I'm your host Benjamin Boster, And today's episode is about the Sahara. The Sahara is a desert spanning North Africa. With an area of 3, 600, 000 square miles, It is the largest hot desert in the world, And the third largest desert overall, Smaller only than the deserts of Antarctica and the Northern Arctic. The name Sahara is derived from the Arabic Sahara, A broken plural form of Sara, Meaning desert. The desert covers much of North Africa, Excluding the fertile region on the Mediterranean sea coast, The Atlas Mountains of the Maghreb, And the Nile Valley in Egypt and the Sudan. It stretches from the Red Sea in the east and the Mediterranean in the north to the Atlantic Ocean on the west, Where the landscape gradually changes from desert to coastal plains. To the south it is bounded by Sahel, A belt of semi-arid tropical savannah around the Niger River valley and the Sudan region of sub-Saharan Africa. The Sahara can be divided into several regions, Including the Western Sahara, The Central Ahaggar Mountains, The Tibesti Mountains, The Ahir Mountains, The Tenere Desert. And the Libyan desert. For several hundred thousand years, The Sahara has alternated between desert and savannah grassland in a 20, 000-year cycle caused by the precession of Earth's axis about 26, 000 years as it rotates around the Sun, Which changes the location of the North African monsoon. The Sahara covers large parts of Algeria, Chad, Egypt, Libya, Mali, Mauritania, Niger. Western Sahara and Sudan. And parts of southern Morocco, Indonesia. It covers 3, 500, 000 square miles, 31% of the African continent. The Sahara is so large and bright that, In theory, It could be detected from other stars as a surface feature of Earth, With near-current technology. The Sahara is a highly diverse desert region composed of Hamada, Rocky plateaus, Ergs, Sand seas covered with sand dunes, Gravel plains, Reg, Dry valleys, Wadi, Dry lakes, And salt flats. Many of its sand dunes rise over 590 feet, And its landscapes are shaped by wind and rare rainfall. The region also includes mountain massifs, Volcanic uplands, Oases, And unusual landforms such as the Rishat structure in Mauritania. Several deeply dissected mountains, Many volcanic, Rise from the desert, Including the Aïr Mountains, The Hagar Mountains, Saharan Atlas, Tibesti Mountains, Adrar des Ifris, And the Red Sea Hills. The highest peak in the Sahara Desert is Emi Kusi, A shield volcano in the Tibesti range of northern Chad. The central Sahara is hyper-arid, 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 and wadis, Where moisture collects. In the central hyperarid region, There are many subdivisions. Tenozruft, The Tenere, The Libyan deserts. The Eastern Desert. The Nubian Desert, And others. These extremely arid areas often receive no rain for years. The Sahara is the world's largest hot desert. It is located in the horse latitudes under the subtropical ridge, A significant belt of semi-permanent subtropical warm core high pressure, Where the air from the upper troposphere usually descends, Warming and drying the lower troposphere and preventing cloud formation. 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. As a consequence, The weather tends to be sunny, Dry and stable with a minimal chance of rainfall. The subtropical ridge is the predominant factor that explains the hot desert climate of this vast region. The descending air flow is the strongest and the most effective over the eastern part of the Great Desert and the Libyan Desert. This is the sunniest, Driest, And most nearly rainless place on the planet, Riving the Atacama Desert, Lying in Chile and Peru. The efforts of local surface low-pressure are extremely limited because upper-level subsidence still continues to block any form of aerosol. 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. Indeed, The extreme aridity of the Sahara is not only explained by the subtropical high pressure. The Atlas Mountains of Algeria, Morocco, And Tunisia also help to enhance the aridity of the northern part of the desert. These major mountain ranges act as a barrier, Causing a strong rain shadow effect on the leeward side by dropping much of the humidity brought by atmospheric disturbances along the polar front, Which affects the surrounding Mediterranean climates. 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. Rainfall in this giant desert has to overcome the physical and atmospheric barriers that normally prevent the production of precipitation. The harsh climate of the Sahara is characterized by extremely low, Unreliable, Highly erratic rainfall, Extremely high sunshine duration values, High temperatures year-round, Negligible rates of relative humidity, A significant diurnal temperature variation, And extremely high levels of potential evaporation, Which are the highest recorded worldwide. 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 100. 4 to 104 degrees Fahrenheit during the hottest month nearly everywhere in the desert except at very high altitudes. The world's highest mean monthly maximum temperature was 116. 6 degrees Fahrenheit, In a remote desert town in the Algerian desert called Bou Bernous, At an elevation of 1, 240 feet above sea level. It is rivaled only by Death Valley, California. 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 parts. The thin northern fringe of the desert receives more winter cloudiness and rainfall due to the arrival of low-pressure systems over the Mediterranean Sea along the polar front, Although very attenuated by the rain shadow effects of the mountains, And the annual average rainfall ranges from 4 inches to 10 inches. The southern fringe of the desert along the border with the Sahel receives summer cloudiness and rainfall due to the arrival of the Intertropical Convergence Zone from the south, And the annual average rainfall ranges from 4 inches to 10 inches. The climate of the Sahara has undergone enormous variations between wet and dry over the last few hundred thousand years, Believed to be caused by long-term changes in the North African climate cycle that alters the path of the North African monsoon, Usually southward. The cycle is caused by a 41, 000 year cycle in which the tilt of the earth changes from 22 degrees and 24. 5 degrees. At present, It is in a dry period, But it is expected that the Sahara will become green again in 15, 000 years. When the North African monsoon is at its strongest, Annual precipitation and subsequent vegetation in the Sahara region increase, Resulting in conditions commonly referred to as the Green Sahara. For a relatively weak North African monsoon, The opposite is true, With decreased annual precipitation and less vegetation, Resulting in a phase of the Sahara climate cycle known as the Desert Sahara. During the last glacial period, The Sahara was much larger than it is today, Extending south beyond its current boundaries. The end of the glacial period brought more rain to the Sahara from about 8, 000 BCE to 6, 000 BCE, Perhaps because of low pressure areas over the collapsing ice sheets to the north. 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. By around 4200 BCE, However, The monsoon retreated south to approximately where it is today, Leading to the gradual desertification of the Sahara. The Sahara is now as dry as it was about 13, 000 years ago. Lake Chad is the remnant of a former inland sea, Paleo Lake Megachad, Which existed during the African Humid Period. At its largest extent, Sometime before 5000 BCE, Lake Megachad was the largest of four Saharan Paleo Lakes, And is estimated to have covered an area of 350, 000 square kilometers. During periods of a wet or green Sahara, The Sahara becomes a savanna grassland and various flora and fauna become more common. Following interpluvial arid periods, The Sahara area then reverts to desert conditions, And the flora and fauna are forced to retreat northwards to the Atlas Mountains, Southwards into West Africa, Or eastwards into the Nile Valley. The flora of the Sahara is highly diversified based on the biogeographical characteristics of this vast desert. Heuristically, The Sahara has three zones based on the amount of rainfall received, The northern Mediterranean, Central, And southern zones. There are two transitional zones, The Mediterranean-Sahara transition and the Sahel transition zone. The Saharan flora comprises around 2, 800 species of vascular plants. Approximately a quarter of these are endemic. About half of these species are common to the flora of the Arabian desert. The central Sahara is estimated to include 500 species of plant, Which is extremely low considering the huge extent of the area. Plants such as acacia trees, Palms, Succulents, Spiny shrubs and grasses have adapted to the arid conditions by growing lower to avoid water loss by strong winds, By storing water in their thick stems to use it in dry periods, By having long roots that travel horizontally to reach the maximum area of water, And to find any surface moisture. And by having small thick leaves or needles to prevent water loss by evapotranspiration. Plant leaves may dry out totally and then recover. Several species of fox live in the Sahara, Including the fennec fox, Pale fox, And rupal's fox. The attics, A large white envelope, Can go nearly a year in the desert without drinking. The Dorcas gazelle is a North African gazelle that can also go for a long time without water. Other notable gazelles include the Rim gazelle and Dama gazelle. The Saharan cheetah, Northwest Africa cheetah, Lives in Algeria, Togo, Niger, Mali, Benin, And Burkina Faso. They are usually pale. Other animals include the monitor lizards, Hyrax, Sand vipers, And small populations of African wild dog, And perhaps only 14 countries and red-necked ostrich. Other animals exist in the Sahara, Birds in particular, Such as African silverbill and black-faced firefinch, Among others. There are also small desert crocodiles in Mauritania and the Entity Plateau of Chad. Dromedary camels and goats are the domesticated animals most commonly found in the Sahara. Because of its qualities of endurance and speed, The dromedary is the favorite animal used by nomads. Scientists have identified more than 230 humid periods in North Africa, Occurring every 21, 000 years for the past 8 million years. In the central Sahara, Engraved and painted rock art were created perhaps as early as 10, 000 years ago, Spanning the Bubaline Period, Kel Esuf Period, Roundhead Period, Pastoral Period, Kabbaline Period, And Cameline Period. The Sahara was then a much wetter place than it is today. Over 30, 000 petroglyphs of river animals, Such as crocodiles, Survive, Was half found in the Tassili Naadjer in southeast Algeria. Fossils of dinosaurs, Including Afravenator jabaria and Uranosaurus, Have also been found here. The modern Sahara though is not lush in vegetation, Except in the Nile Valley at a few oases, And in the northern highlands where Mediterranean plants such as the olive tree are found to grow. Shifts in Earth's axis increased temperatures and decreased precipitation, Which caused an abrupt beginning of North Africa desertification about 5, 400 years ago. The Kiffian culture is a prehistoric industry or domain that existed between 10, 000 and 8, 000 years ago in the Sahara, During the Neolithic sub-pluvial. Human remains from this culture were found in 2000 at a site known as Kobero, Located in Niger, In the Teneri Desert. The site is known as the largest and earliest grave of Stone Age people in the Sahara. The Kyphians were skilled hunters. Bones of many large savanna animals that were discovered in the same area suggest that they lived on the shores of a lake that were present during the Holocene wet phase, A period when the Sahara was verdant and wet. The Kiffian people were tall, Standing over six feet in height. Traces of the Kiffian culture do not exist after 8, 000 years ago, As the Sahara went through a dry period for the next thousand years. After this time the Tenerian culture colonized the area. During the Neolithic era, Both the onset of desertification around 9500 BCE, The central Sudan had been a rich environment supporting a large population, Ranging across what is now barren desert, Like the Wadi el-Khab. By the 5th millennium BCE, The people who inhabited what is now called Nubia were full participants in the agricultural revolution, Living a settled lifestyle with domesticated plants and animals. Saharan rock art of cattle and herdsmen suggests the presence of a cattle cold like those found in Sudan and other pastoral societies in Africa today. Megaliths found at Napta Playa are overt examples of probably the world's first known Archeoastronomy devices predating Stonehenge by some 2, 000 years. Archaeological evidence has attested that population settlements occurred in Nubia as early as the late Pleistocene era and from the 5th millennium BCE onwards, Whereas there is no or scanty evidence of human presence in the Egyptian Nile Valley during this period, Which may be due to problems in site preservation. By 6000 BCE, Pre-dynastic Egyptians in the southwestern corner of Egypt were herding cattle and constructing large buildings. Subsistence in organized and permanent settlements in pre-dynastic Egypt by the middle of the 6th millennium BCE, Centered predominantly on cereal and animal agriculture, Cattle, Goats, Pigs, And sheep. Burial in desert environments appears to enhance Egyptian preservation rights, And the dead were buried facing due west. Several scholars have argued that the African origins of the Egyptian civilization derived from pastoral communities, Which emerged in both the Egyptian and Sudanese regions of the Nile Valley in the 5th millennium BCE. By 3400 BCE, The Sahara was as dry as it is today, Due to reduced precipitation and higher temperatures, Resulting from a shift in Earth's orbit. As a result of this erratification, It became a largely impenetrable barrier to humans, With the remaining settlements mainly being concentrated around the numerous oases that dot the landscape. Little trade or commerce is known to have passed through the interior in subsequent periods, The only major exception being the Nile Valley. Denial, However, Was impassable at several cataracts, Making trade and contact by boat difficult. The Harateen speak Maghrebi Arabic dialects and Berber languages. They are believed to largely descend from native ancient black populations that inhabited the Sahara. The people of Phoenicia, Who flourished from 1200 to 800 BCE, Created a chain of settlements along the coast of North Africa, And traded extensively with its inhabitants. Has put them in contact with the people in ancient Libya, Who were the ancestors of the people who speak Berber languages in North Africa and the Sahara today. The Libyco-Berber alphabet of the ancient Libyans of North Africa seems to have been based on Phoenician, And its descendant to Finag is still used today by the Berber Tuareg of the Central Sahara. By 5000 BCE, Greeks arrived in the desert. Greek traders spread along the eastern coast of the desert, Establishing trading colonies along the Red Sea. The Carthaginians explored the Atlantic coast of the desert, But the turbulence of the waters and the lack of markets caused a lack of presence further south than modern Morocco. Centralized states thus surrounded the desert on the north and east. It remained outside the control of these states. Raids from the nomadic Berber people of the desert were of constant concern to those living on the edge of the desert. Between the 1st century BCE and the 4th century CE, Several Roman expeditions into the Sahara were conducted by groups of military and commercial units of Romans. In the post-World War II era, Several mines and communities have developed to use the desert's natural resources. These include large deposits of oil and natural gas in Algeria and Libya, And large deposits of phosphates in Morocco and Western Sahara. Libya's great man-made river is the world's largest irrigation project. The project uses a pipeline system that pumps fossil water from the Nubian sandstone aquifer system to cities in the populous Libyan northern Mediterranean coast, Including Tripoli and Benghazi. The people of the Sahara are of various origins. Among them, The Amazigh, Including the Tuareg, Various Arabized Amazigh groups, Such as the Hassaniyya-speaking Sarawis, Whose populations include the Zanaga, A tribe whose name is a remnant of the prehistoric Zanaga language. Other major groups of the people include the Tubu, Nubians, Sagawa, Kanuri, Hausa, Songhai, Beja, And Fula-Fulani. The archaeological evidence from the Holocene period has shown that Nilo-Saharan speaking groups had populated the central and southern Sahara before the influx of Berber and Arabic speakers around 1500 years ago, Who now largely populate the Sahara in the modern era. The Harateans are believed to largely descend from native ancient black populations that inhabited the Sahara. Arabic dialects are the most widely spoken languages in the Sahara. Arabic, Berber, And its variants, Now regrouped under the term Amazigh and Peja languages, Are part of the Afro-Asiatic or Hamito-Semitic family. Unlike neighboring West Africa and the central governments of the states that comprise the Sahara, The French language bears little relevance to interpersonal discourse and commerce within the region, Its people retaining staunch ethnic and political affiliations with Tuareg and Berber leaders and culture.