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104-415: This geography of Egypt article is a stub . You can help Misplaced Pages by expanding it . This Sudan location article is a stub . You can help Misplaced Pages by expanding it . Geography of Egypt 27°00′N 30°00′E  /  27.000°N 30.000°E  / 27.000; 30.000 The geography of Egypt relates to two regions: North Africa and West Asia . Egypt has coastlines on

208-426: A consequence, the weather tends to be sunny, dry and stable with a minimal chance of rainfall. Subsiding, diverging, dry air masses associated with subtropical high-pressure systems are extremely unfavorable for the development of convectional showers. The subtropical ridge is the predominant factor that explains the hot desert climate ( Köppen climate classification BWh ) of this vast region. The descending airflow

312-519: A healthy adult. The Saharan silver ant is unique in that due to the extreme high temperatures of their habitat, and the threat of predators, the ants are active outside their nest for only about ten minutes per day. 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 favourite animal used by nomads . Human activities are more likely to affect

416-569: A mean altitude of some 1000 m, constitutes an exception to the uninterrupted territory of basement rocks covered by layers of horizontally bedded sediments forming a massive plain or low plateau. The Great Sand Sea lies within the desert's plain and extends from the Siwa Oasis to Jilf al Kabir . Escarpments (ridges) and deep depressions (basins) exist in several parts of the Western Desert, and no rivers or streams drain into or out of

520-765: A narrow coastal shelf that slopes into the Red Sea and the Gulf of Aqaba . The elevation of Sinai's southern rim is about 1,000 m. Moving northward, the elevation of this limestone plateau decreases. The northern third of Sinai is a flat, sandy coastal plain, which extends from the Suez Canal into the Gaza Strip and Israel . Before the Israeli military occupied Sinai during the June 1967 War (Arab-Israeli war, also known as

624-455: A natural drainage pattern that rarely functions because of insufficient rainfall. It also has a complex of irregular, sharply cut wadis that extend westward toward the Nile. The desert environment extends all the way to the Red Sea coast. The Sinai Peninsula is a triangular-shaped peninsula , about 61,100 km in area slightly smaller than Latvia (64 573 km ). Similar to the desert,

728-648: A steeper gradient and therefore flows more swiftly than the White Nile, which it joins at Khartoum. Unlike the White Nile, the Blue Nile carries a considerable amount of sediment . For several kilometers north of Khartoum, water closer to the eastern bank of the river, coming from the Blue Nile, is visibly muddy , while that closer to the western bank, and coming from the White Nile, is clearer. The much shorter Atbarah River, which also originates in Ethiopia, joins

832-569: A summer rainy season that extends across Africa from east to west. The southern limit of the Sahara is indicated botanically by the southern limit of Cornulaca monacantha (a drought-tolerant member of the Chenopodiaceae ), or northern limit of Cenchrus biflorus , a grass typical of the Sahel. According to climatic criteria, the southern limit of the Sahara corresponds to the 150 mm (5.9 in) isohyet of annual precipitation (this

936-542: A surface feature of Earth, with near-current technology. The Sahara is mainly rocky hamada (stone plateaus); ergs (sand seas – large areas covered with sand dunes ) form only a minor part, contrary to common misconception , but many of the sand dunes are over 180 metres (590 ft) high. Wind or rare rainfall shape the desert features: sand dunes, dune fields, sand seas, stone plateaus, gravel plains ( reg ), dry valleys ( wadi ), dry lakes ( oued ), and salt flats ( shatt or chott ). Unusual landforms include

1040-529: Is The principles and objects of geology, with special reference to the geology of Egypt (1911) by W. F. Hume Egypt's geological history has produced four major physical regions : Despite covering only about 5% of the total area of Egypt; the Nile Valley and Nile Delta are the most important regions, being the country's only cultivable regions and supporting about 99% of the population. The Nile valley extends approximately 800  km from Aswan to

1144-527: Is a desert spanning across North Africa . With an area of 9,200,000 square kilometres (3,600,000 sq mi), 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 Arabic : صَحَارَى , romanized :  ṣaḥārā /sˤaħaːraː/ , a broken plural form of ṣaḥrā' ( صَحْرَاء /sˤaħraːʔ/ ), meaning "desert". The desert covers much of North Africa , excluding

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1248-526: Is a key component of the economy in rural areas, though some people are employed in the tourist industry or other non-farm occupations. In 1992, the percentage of Egypt's population employed in agriculture was 33 percent. The agricultural industry is dependent on irrigation from the Nile river. This is a list of the extreme points of Egypt , the points that are farther north, south, east or west than any other location. Sahara The Sahara ( / s ə ˈ h ɑːr ə / , / s ə ˈ h ær ə / )

1352-660: Is a long-term average, since precipitation varies annually). Important cities located in the Sahara include Nouakchott , the capital of Mauritania; Tamanrasset , Ouargla , Béchar , Hassi Messaoud , Ghardaïa , and El Oued in Algeria; Timbuktu in Mali; Agadez in Niger; Ghat in Libya; and Faya-Largeau in Chad. The Sahara is the world's largest hot desert . It is located in

1456-422: Is a north African gazelle that can also go for a long time without water. Other notable gazelles include the rhim gazelle and dama gazelle . The Saharan cheetah ( northwest African cheetah ) lives in Algeria, Togo , Niger, Mali, Benin , and Burkina Faso . There remain fewer than 250 mature cheetahs, which are very cautious, fleeing any human presence. The cheetah avoids the sun from April to October, seeking

1560-629: Is a prehistoric industry, or domain, that existed between 10,000 and 8,000 years ago in the Sahara, during the Neolithic Subpluvial . Human remains from this culture were found in 2000 at a site known as Gobero , located in Niger in the Ténéré Desert . The site is known as the largest and earliest grave of Stone Age people in the Sahara. The Kiffians were skilled hunters . Bones of many large savannah animals that were discovered in

1664-465: Is associated with high rates of wind-blown mineral dust, and these dust levels are found as expected in marine cores from the north tropical Atlantic. But around 12,500 BCE the amount of dust in the cores in the Bølling / Allerød phase suddenly plummets and shows a period of much wetter conditions in the Sahara, indicating a Dansgaard-Oeschger (DO) event (a sudden warming followed by a slower cooling of

1768-403: Is estimated to include five hundred species of plants, 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

1872-667: Is the strongest and the most effective over the eastern part of the Great Desert, in the Libyan Desert: this is the sunniest, driest and the most nearly "rainless" place on the planet, rivaling the Atacama Desert , lying in Chile and Peru . The rainfall inhibition and the dissipation of cloud cover are most accentuated over the eastern section of the Sahara rather than the western. The prevailing air mass lying above

1976-422: Is very unreliable and erratic in the Sahara as it may vary considerably year by year. In full contrast to the negligible annual rainfall amounts, the annual rates of potential evaporation are extraordinarily high, roughly ranging from 2,500 millimetres (100 in) per year to more than 6,000 millimetres (240 in) per year in the whole desert. Nowhere else on Earth has air been found as dry and evaporative as in

2080-543: The Adrar of Mauritania and a value of 75 °C (167 °F) has been measured in Borkou , northern Chad. Due to lack of cloud cover and very low humidity, the desert usually has high diurnal temperature variations between days and nights. However, it is a myth that the nights are especially cold after extremely hot days in the Sahara. On average, nighttime temperatures tend to be 13–20 °C (23–36 °F) cooler than in

2184-488: The Algerian Desert called Bou Bernous , at an elevation of 378 metres (1,240 ft) above sea level, and only Death Valley, California rivals it. Other hot spots in Algeria such as Adrar , Timimoun , In Salah , Ouallene , Aoulef , Reggane with an elevation between 200 and 400 metres (660 and 1,310 ft) above sea level get slightly lower summer average highs, around 46 °C (114.8 °F) during

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2288-765: The Late Pleistocene Iberomaurusians , early Holocene Capsians , and mid-Holocene Mechta groups, whereas the Tenerian crania are more like those of Mediterranean groups. Graves show that the Tenerians observed spiritual traditions, as they were buried with artifacts such as jewelry made of hippo tusks and clay pots. The most interesting find is a triple burial, dated to 5300 years ago, of an adult female and two children, estimated through their teeth as being five and eight years old, hugging each other. Pollen residue indicates they were buried on

2392-672: The Mediterranean Sea , the River Nile , and the Red Sea . Egypt borders Libya to the west, Israel to the east and Sudan to the south. Egypt has an area of 1,002,450 km (387,050 sq mi). The longest straight-line distance in Egypt from north to south is 1,420 km (880 mi), while that from east to west measures 1,275 km (792 mi). Egypt has more than 2,900 km (1,800 mi) of coastline on

2496-762: 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 Aïr Mountains , the Ténéré desert, and the Libyan Desert . For several hundred thousand years, the Sahara has alternated between desert and savanna grassland in a 20,000-year cycle caused by

2600-509: The Nile river south from Cairo to Aswan and five frontier governorates covering Sinai and the deserts that lie west and east of the Nile river. Egypt is predominantly desert . 35,000 km – 3.5% – of the total land area is cultivated and permanently settled. Most of the country lies within the wide band of desert that stretches eastwards from Africa's Atlantic Coast across the continent and into southwest Asia. Historically relevant here

2704-694: The Richat Structure in Mauritania. 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 . The highest peak in the Sahara is Emi Koussi , a shield volcano in the Tibesti range of northern Chad. The central Sahara is hyperarid , with sparse vegetation. The northern and southern reaches of

2808-412: The cliffs of sandstone and granite created by the flow of the river over many centuries. Below Aswan, the cultivated floodplain strip widens to as much as twenty km. North of Isna (160  km north of Aswan), the plateau on both sides of the valley rises to as much as 550 m above sea level; at Qina (some 90  km north of Isna) the 300-m limestone cliffs force the Nile to change course towards

2912-474: 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

3016-514: 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 and Tunisia . It covers 9 million square kilometres (3,500,000 sq mi), 31% of

3120-858: The topographic channel that permits the Nile to flow across the Sahara , Egypt would be entirely desert. The length within Egypt of the River Nile in its northwards course from three central African sources – the White Nile , the Blue Nile , and the Atbara – totals some 1,600  km. The White Nile, which begins at Lake Victoria in Uganda , supplies about 28% of the Nile's Egyptian waters. In its course from Lake Victoria to Juba in South Sudan ,

3224-509: 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 kilometres (4,200,000 sq mi). It is one of three distinct physiographic provinces of the African massive physiographic division . The Sahara is so large and bright that, in theory, it could be detected from other stars as

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3328-417: The African humid period. At its largest extent, sometime before 5000 BCE, Lake Mega-Chad was the largest of four Saharan paleolakes, and is estimated to have covered an area of 350,000 km . The Sahara pump theory describes this cycle. During periods of a wet or " Green Sahara ", the Sahara becomes a savanna grassland and various flora and fauna become more common. Following inter-pluvial arid periods,

3432-670: The Delta, the erosion of the river's banks in Upper Egypt , and the erosion of the alluvial fan along the shore of the Mediterranean Sea. The Western Desert covers an area of some 700,000  km , thereby accounting for around two-thirds of Egypt's total land area. This immense desert to the west of the Nile spans the area from the Mediterranean Sea southwards to the Sudanese border. The desert's Jilf al Kabir Plateau , at

3536-412: 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. The world's highest officially recorded average daily high temperature was 47 °C (116.6 °F) in a remote desert town in

3640-486: The Intertropical Convergence Zone from the south and the annual average rainfall ranges from 100 millimetres (4 in) to 250 millimetres (10 in). For example, Timbuktu, Mali and Agadez , Niger are found in this zone. 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

3744-523: 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. Gobero was discovered in 2000 during an archaeological expedition led by Paul Sereno , which sought dinosaur remains. Two distinct prehistoric cultures were discovered at the site: the early Holocene Kiffian culture, and

3848-462: The Mediterranean Sea, the Gulf of Suez , and the Gulf of Aqaba . It has an Exclusive Economic Zone of 263,451 km (101,719 sq mi). Egypt is divided into 28 governorates , which include two city-governortes: Alexandria ( Alexandria Governorate ) and Cairo ( Cairo Governorate ). There are nine governorates of Lower Egypt in the Nile Delta region, ten of Upper Egypt along

3952-463: The Nile in ancient times. For centuries sweet water artesian wells in the Fayyum Oasis have permitted extensive cultivation in an irrigated area that extends over 1,800 square kilometers (695 sq mi). The topographic features of the desert region east of the Nile differ from those to the west of the Nile. The Eastern Desert is relatively mountainous. The elevation rises abruptly from

4056-431: The Nile to overflow its banks and deposit a layer of fertile mud over adjacent fields. The great flood of the main Nile usually occurred in Egypt during August, September, and October, but it sometimes began as early as June at Aswan and often did not completely wane until January. The Nile enters Egypt a few kilometers north of Wadi Halfa , a Sudanese town that was completely rebuilt on high ground when its original site

4160-556: The Nile's waters in the low-water season and 68% during the high-water season. In contrast, the White Nile provides only 10% of the Nile's waters during the high-water season but contributes more than 80% during the low-water period. Thus, before the Aswan High Dam was completed in 1971, the White Nile watered the Egyptian stretch of the river throughout the year, whereas the Blue Nile, carrying seasonal rain from Ethiopia, caused

4264-545: The Nile, and a downward-sloping plateau of sand gives way within 100  km to arid, defoliated, rocky hills running north and south between the Sudan border and the Delta. The hills reach elevations of more than 1,900 m. The region's most prominent feature is the easterly chain of rugged mountains, the Red Sea Hills , which extend from the Nile Valley eastward to the Gulf of Suez and the Red Sea. This elevated region has

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4368-462: 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 Ennedi Plateau of Chad. The deathstalker scorpion can be 10 cm (3.9 in) long. Its venom contains large amounts of agitoxin and scyllatoxin and is very dangerous; however, a sting from this scorpion rarely kills

4472-472: 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 . This separates populations of some of the species in areas with different climates , forcing them to adapt , possibly giving rise to allopatric speciation . It is also proposed that humans accelerated

4576-528: The Sahara is strongly influenced by the North Atlantic Oscillation (NAO), with warmer winter temperatures during negative NAO events and cooler winters with more frosts when the NAO is positive. This is because the weaker clockwise flow around the eastern side of the subtropical anticyclone during negative NAO winters, although too dry to produce more than negligible precipitation, does reduce

4680-504: 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. Because of this extreme heating process, a thermal low is usually noticed near the surface, and is the strongest and the most developed during the summertime. The Sahara High represents

4784-638: The Sahara region. However, at least two instances of snowfall have been recorded in Sahara, in February 1979 and December 2016, both in the town of Ain Sefra . 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. Another theory is that the monsoon was weakened when

4888-649: The Six-Day War), a single Egyptian governorate administered the whole peninsula. By 1982 after all of Sinai was returned to Egypt, the central government divided the peninsula into two governorates. North Sinai has its capital at Al Arish and the South Sinai has its capital in El Tor. The abundance of life in the Sinai Peninsula may not be immediately apparent. This again has its roots in the way in which

4992-713: The Tassili n'Ajjer in southeast Algeria. Fossils of dinosaurs , including Afrovenator , Jobaria and Ouranosaurus , 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

5096-546: The White Nile's channel drops more than 600 m. In its 1,600-km course from Juba to Khartoum , Sudan 's capital, the river descends just 75 m. In South Sudan, the White Nile passes through the Sudd , a wide, flat plain covered with swamp vegetation and slows almost to the point of stagnation . The Blue Nile, which originates at Lake Tana in Ethiopia , provides on average some 58% of the Nile's Egyptian waters. This river has

5200-595: 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 2800 species of vascular plants . Approximately a quarter of these are endemic . About half of these species are common to the flora of the Arabian deserts. The central Sahara

5304-550: The ancient Tethys Sea dried up during the Tortonian period around 7 million years ago. 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

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5408-415: The animals of the desert have adapted to life here. Many species, mammals especially, but also reptiles and even birds such as owls, are nocturnal. They spend the daylight hours in the relative cool of burrows, under boulders or in crevices and cracks in the rock. Many of these creatures will only be apparent from their tracks and trails or from a fleeting glimpse of a diminutive gerbil, or zig-zigging hare, in

5512-418: The area. The government has considered the Western Desert a frontier region and has divided it into two governorates at about the twenty-eighth parallel: Matruh to the north and New Valley (Al Wadi al Jadid) to the south. There are seven important depressions in the Western Desert, and all are considered oases except the largest, Qattara , the water of which is salty. The Qattara Depression , which includes

5616-421: 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

5720-475: The car headlights at night. Even those animals that do brave the heat of the day are normally only active in the early morning or evening. In the 1971 census, 57 percent of Egypt's population was counted as rural, including those residing in agricultural areas in the Nile Valley and Delta, as well as the much smaller number of persons living in desert areas. Rural areas differ from the urban in terms of poverty, fertility rates, and other social factors. Agriculture

5824-616: The climate). The moister Saharan conditions had begun about 12,500 BCE, with the extension of the ITCZ northward in the northern hemisphere summer, bringing moist wet conditions and a savanna climate to the Sahara, which (apart from a short dry spell associated with the Younger Dryas ) peaked during the Holocene thermal maximum climatic phase at 4000 BCE when mid-latitude temperatures seem to have been between 2 and 3 degrees warmer than in

5928-445: The construction of the Aswan Dam , agriculture in the Nile valley depends on irrigation . The Nile delta consists of flat, low-lying areas. Some parts of the delta are marshy and water-logged, and thus not suitable for agriculture. Other areas of the delta are used for agriculture. The Nile Valley and Delta, the most extensive oasis on earth, was created by the world's longest river and its seemingly inexhaustible sources. Without

6032-438: The country's lowest point, encompasses 19,605 square kilometers (7,570 sq mi), which is similar to the size of Lake Ontario . It is largely below sea level and is 133 meters (436 ft) below sea level at the lowest. Badlands , salt marshes and salt lakes cover the sparsely inhabited Qattara Depression. Limited agricultural production, the presence of some natural resources, and permanent settlements are found in

6136-474: The daytime. The smallest variations are found along the coastal regions due to high humidity and are often even lower than a 10 °C (18 °F) difference, while the largest variations are found in inland desert areas where the humidity is the lowest, mainly in the southern Sahara. Still, it is true that winter nights can be cold, as it can drop to the freezing point and even below, especially in high-elevation areas. The frequency of subfreezing winter nights in

6240-469: The desert experiences around three to five months when the average high strictly 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 strictly exceeds 40 °C (104 °F). Some examples of this are Bilma , Niger and Faya-Largeau, Chad. The annual average daily temperature exceeds 20 °C (68 °F) everywhere and can approach 30 °C (86 °F) in

6344-405: The desert, along with the highlands, have areas of sparse grassland and desert shrub , with trees and taller shrubs in wadis , where moisture collects. In the central, hyperarid region, there are many subdivisions of the great desert: Tanezrouft , the Ténéré , the Libyan Desert , the Eastern Desert , the Nubian Desert and others. These extremely arid areas often receive no rain for years. To

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6448-475: The drying-out period from 6000 to 2500 BCE by pastoralists overgrazing available grassland. The growth of speleothems (which requires rainwater) was detected in Hol-Zakh, Ashalim , Even-Sid, Ma'ale-ha-Meyshar, Ktora Cracks, Nagev Tzavoa Cave, and elsewhere, and has allowed tracking of prehistoric rainfall. The Red Sea coastal route was extremely arid before 140 and after 115 kya (thousands of years ago). Slightly wetter conditions appear at 90–87 kya, but it still

6552-477: The eastern continental extension of the Azores High , centered over the North Atlantic Ocean . The subsidence of the Sahara High nearly reaches the ground during the coolest part of the year, while it is confined to the upper troposphere during the hottest periods. The effects of local surface low pressure are extremely limited because upper-level subsidence still continues to block any form of air ascent. Also, to be protected against rain-bearing weather systems by

6656-486: The edge of the desert thousands of years ago, since the end of the last glacial period . In the Central Sahara, engraved and painted rock art were created perhaps as early as 10,000 years ago, spanning the Bubaline Period , Kel Essuf Period , Round Head Period , Pastoral Period , Caballine 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, with half found in

6760-419: 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 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

6864-526: The first century AD, seven branches of the Nile once ran through the delta. According to later accounts, the Nile had, by around the twelfth century, just six branches. Since then, nature and man have closed all but two main outlets: the east branch, Damietta (also known as Dumyat; 240  km long), and the west branch, Rosetta (235  km long). Both outlets are named after the ports located at their respective mouths. A network of drainage and irrigation canals supplements these remaining outlets. In

6968-416: The flow of dry, cold air from higher latitudes of Eurasia into the Sahara significantly. 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 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

7072-699: The habitat in areas of permanent water (oases) or where water comes close to the surface. Here, the local pressure on natural resources can be intense. The remaining populations of large mammals have been greatly reduced by hunting for food and recreation. In recent years development projects have started in the deserts of Algeria and Tunisia using irrigated water pumped from underground aquifers. These schemes often lead to soil degradation and salinization . Researchers from Hacettepe University have reported that Saharan soil may have bio-available iron and also some essential macro and micro nutrient elements suitable for use as fertilizer for growing wheat. People lived on

7176-405: The highest recorded worldwide. 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 highest values are very close to

7280-448: The hottest months of the year. Salah, well known in Algeria for its extreme heat, has average high temperatures of 43.8 °C (110.8 °F), 46.4 °C (115.5 °F), 45.5 °C (113.9 °F) and 41.9 °C (107.4 °F) in June, July, August and September respectively. 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

7384-433: The hottest regions year-round. However, most of the desert has a value in excess of 25 °C (77 °F). Sand and ground temperatures are even more extreme. During daytime, the sand temperature is extremely high: it can easily reach 80 °C (176 °F) or more. A sand temperature of 83.5 °C (182.3 °F) has been recorded in Port Sudan . Ground temperatures of 72 °C (161.6 °F) have been recorded in

7488-406: 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 8000 BCE to 6000 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

7592-458: The late nineteenth century, The hypothesis was later formally proposed and tested by the meteorologist John Kutzbach in 1981. Kutzbach's ideas about the impacts of insolation on global monsoonal patterns have become widely accepted today as the underlying driver of long-term monsoonal cycles. Kutzbach never formally named his hypothesis and as such it is referred to here as the " Orbital Monsoon Hypothesis " as suggested by Ruddiman in 2001. During

7696-581: 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

7800-562: The main Nile north of Khartoum between the fifth and sixth cataracts (areas of steep rapids) and provides about 14% of the Nile's waters in Egypt. During the low-water season, which runs from January to June, the Atbarah shrinks to a number of pools. But, in late summer, when torrential rains fall on the Ethiopian Highlands , the Atbarah provides 22% of the Nile's flow. The Blue Nile has a similar pattern. It contributes 17% of

7904-419: 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 Rüppell's fox . The addax , a large white antelope , can go nearly a year in the desert without drinking. The dorcas gazelle

8008-437: The middle Holocene Tenerian culture . The post-Kiffian desiccation lasted until around 4600 BCE, when the earliest artefacts associated with the Tenerians have been dated to. Some 200 skeletons have been discovered at Gobero. The Tenerians were considerably shorter in height and less robust than the earlier Kiffians. Craniometric analysis also indicates that they were osteologically distinct. The Kiffian skulls are akin to those of

8112-470: The mighty river into a large and predictable irrigation ditch . Lake Nasser, the world's largest artificial lake, has enabled planned use of the Nile regardless of the amount of rainfall in Central Africa and East Africa . The dams have also affected the Nile Valley's fertility , which was dependent for centuries not only on the water brought to the arable land but also on the materials left by

8216-422: The north, near the coast, the Nile delta embraces a series of salt marshes and lakes , the most notable among which are Idku , Al Burullus , and Manzilah . The fertility and productivity of the land adjacent to the Nile depend largely on the silt deposited by floodwaters. Archaeological research indicates that people once lived at a much higher elevation along the river than they do today, probably because

8320-581: The north, the Sahara skirts the Mediterranean Sea in Egypt and portions of Libya, but in Cyrenaica and the Maghreb , the Sahara borders the Mediterranean forest, woodland, and scrub eco-regions of northern Africa, all of which have a Mediterranean climate characterized by hot summers and cool and rainy winters. According to the botanical criteria of Frank White and geographer Robert Capot-Rey,

8424-540: The northern limit of the Sahara corresponds to the northern limit of date palm cultivation and the southern limit of the range of esparto , a grass typical of the Mediterranean climate portion of the Maghreb and Iberia . The northern limit also corresponds to the 100 mm (3.9 in) isohyet of annual precipitation. To the south, the Sahara is bounded by the Sahel, a belt of dry tropical savanna with

8528-459: 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". The idea that changes in insolation (solar heating) caused by long-term changes in Earth's orbit are a controlling factor for the long-term variations in the strength of monsoon patterns across the globe was first suggested by Rudolf Spitaler in

8632-535: The other six depressions, all of which have fresh water provided by the Nile or by local groundwater . The Siwah Oasis, close to the Libyan border and west of Qattara, is isolated from the rest of Egypt but has sustained life since ancient times. The Siwa's cliff-hung Temple of Amun was renowned for its oracles for more than 1,000 years. Herodotus and Alexander the Great were among the many illustrious people who visited

8736-485: The outskirts of Cairo. The Nile Valley is known as Upper Egypt , while the Nile Delta region is known as Lower Egypt . Steep rocky cliffs rise along the banks of the Nile in some stretches, while other areas along the Nile are flat, with space for agricultural production. In the past, flooding of the Nile during the summer provided silt and water to make agriculture possible on land that is otherwise very dry. Since

8840-467: The peninsula contains mountains in its southern sector that are a geological extension of the Red Sea Hills, the low range along the Red Sea coast that includes Mount Catherine (Jabal Katrinah), the country's highest point, at 2,642 m above sea-level. The Red Sea may have been named after these mountains, which are red. The southern side of the peninsula has a sharp escarpment that subsides after

8944-419: 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

9048-401: The polar front, although very attenuated by the rain shadow effects of the mountains and the annual average rainfall ranges from 100 millimetres (4 in) to 250 millimetres (10 in). For example, Biskra , Algeria, and Ouarzazate , Morocco, are found in this zone. The southern fringe of the desert along the border with the Sahel receives summer cloudiness and rainfall due to the arrival of

9152-406: The recent past. Analysis of Nile River deposited sediments in the delta also shows this period had a higher proportion of sediments coming from the Blue Nile , suggesting higher rainfall also in the Ethiopian Highlands . This was caused principally by a stronger monsoonal circulation throughout the sub-tropical regions, affecting India, Arabia and the Sahara. Lake Victoria only recently became

9256-491: The river was higher or the floods more severe. The timing and amount of annual flow were always unpredictable. Measurements of annual flows as low as 1.2 billion m and as high as 4.25 billion m have been recorded. For centuries Egyptians attempted to predict and take advantage of these flows and thereby moderate the severity of floods. The construction of dams on the Nile, particularly the Aswan High Dam, transformed

9360-608: The same area suggest that they lived on the shores of a lake that was 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. Craniometric analysis indicates that this early Holocene population was closely related to the Late Pleistocene Iberomaurusians and early Holocene Capsians of the Maghreb, as well as mid-Holocene Mechta groups. Traces of

9464-412: The scale of the Nile floods between 2700 and 2100 BCE. The Sahara comprises several distinct ecoregions . With their variations in temperature, rainfall, elevation, and soil, these regions harbor distinct communities of plants and animals. The flora of the Sahara is highly diversified based on the bio-geographical characteristics of this vast desert. Floristically , the Sahara has three zones based on

9568-521: The shelter of shrubs such as balanites and acacias. They are unusually pale. The other cheetah subspecies ( northeast African cheetah ) lives in Chad, Sudan and the eastern region of Niger. However, it is currently extinct in the wild in Egypt and Libya. There are approximately 2000 mature individuals left in the wild. Other animals include the monitor lizards , hyrax , sand vipers , and small populations of African wild dog , in perhaps only 14 countries and red-necked ostrich . Other animals exist in

9672-538: The source of the White Nile and dried out almost completely around 15 kya. The sudden subsequent movement of the ITCZ southwards with a Heinrich event (a sudden cooling followed by a slower warming), linked to changes with the El Niño-Southern Oscillation cycle, led to a rapid drying out of the Saharan and Arabian regions, which quickly became desert. This is linked to a marked decline in

9776-615: The southwest for about 60  km before it turns northwest for about 160  km to Asyut. Northward from Asyut, the escarpments on both sides diminish, and the valley widens to a maximum of 22  km. At Cairo, the Nile spreads out over what was once a broad estuary , subsequently filled by silt deposits to form what is now a fertile, fan-shaped delta some 250  km wide at its seaward extremity and extending about 160 km from north to south. The Nile Delta covers approximately 22,000 km (roughly equivalent in area to that of Massachusetts ). According to historical accounts from

9880-561: The strongest anticyclonic weather regime, and the annual average rainfall can drop to less than 1 millimetre (0.04 in). In fact, most of the Sahara receives less than 20 millimetres (0.8 in). Of the 9,000,000 square kilometres (3,500,000 sq mi) of desert land in the Sahara, an area of about 2,800,000 square kilometres (1,100,000 sq mi) (about 31% of the total area) receives an annual average rainfall amount of 10 millimetres (0.4 in) or less, while some 1,500,000 square kilometres (580,000 sq mi) (about 17% of

9984-625: The temple in the pre-Christian era. The other major oases form a topographic chain of basins extending from the Faiyum Oasis (sometimes called the Fayyum Depression) which lies 60 kilometers (37 mi) southwest of Cairo , south to the Bahariya , Farafirah , and Dakhilah oases before reaching the country's largest oasis, Kharijah . A brackish lake, Birket Qarun , at the northern reaches of Al Fayyum Oasis, drained into

10088-503: The theoretical maximum value. A value of 4300 hours (98%) of the time would be recorded in Upper Egypt ( Aswan , Luxor ) and in the Nubian Desert ( Wadi Halfa ). The annual average direct solar irradiation is around 2,800 kWh/(m year) in the Great Desert. The Sahara has a huge potential for solar energy production. The high position of the Sun, the extremely low relative humidity, and the lack of vegetation and rainfall make

10192-472: The tilt of the earth changes between 22° and 24.5°. 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,

10296-478: The total area) receives an average of 5 millimetres (0.2 in) or less. The annual average rainfall is virtually zero over a wide area of some 1,000,000 square kilometres (390,000 sq mi) in the eastern Sahara comprising deserts of: Libya, Egypt and Sudan ( Tazirbu , Kufra , Dakhla , Kharga , Farafra , Siwa , Asyut , Sohag , Luxor, Aswan, Abu Simbel , Wadi Halfa) where the long-term mean approximates 0.5 millimetres (0.02 in) per year. Rainfall

10400-577: The water. Researchers have estimated that beneficial silt deposits in the valley began about 10,000 years ago. The average annual deposit of arable soil through the course of the river valley amounted to some nine metres. Analysis of the flow revealed that 10.7 million tons of solid matter passed Cairo each year. Today the Aswan High Dam obstructs most of this sediment, now retained in Lake Nasser. The reduction in annual silt deposits has contributed to rising water tables and increasing soil salinity in

10504-403: 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, paleolake Mega-Chad, which existed during

10608-470: Was just one tenth the rainfall around 125 kya. In the southern Negev Desert speleothems did not grow between 185 and 140 kya ( MIS 6), 110–90 (MIS 5.4–5.2), nor after 85 kya nor during most of the interglacial period (MIS 5.1), the glacial period and Holocene . This suggests that the southern Negev was arid-to-hyper-arid in these periods. During the Last Glacial Maximum (LGM) the Sahara

10712-575: Was more extensive than it is now with the extent of the tropical forests being greatly reduced, and the lower temperatures reduced the strength of the Hadley Cell . This is a climate cell which causes rising tropical air of the Inter-Tropical Convergence Zone (ITCZ) to bring rain to the tropics, while dry descending air, at about 20 degrees north , flows back to the equator and brings desert conditions to this region. It

10816-408: Was submerged in the reservoir created by the Aswan High Dam. As a result of the dam's construction, the Nile actually begins its flow into Egypt as Lake Nasser , which extends southwards from the dam for 320  km to the border and for an additional 158  km within Sudan. Lake Nasser's waters fill the area through Lower Nubia (Upper Egypt and northern Sudan) within the narrow canyon between

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