Sahara

The Sahara is nine million square kilometers, the largest hot desert in the world. That's about the size of the entire United States, or 26 times the size of Germany. It extends from the African Atlantic coast to the Red Sea coast and approximately forms a trapezoid 4500-5500 kilometers west to east and from 1500 to 2000 km north-south extent. It belongs to the turning circle deserts.

The Sahara is mostly a rocky desert or rocky desert ( Hammada ), or gravel or gravel desert ( Serir ); the most famous sandy desert ( Erg ) stands at around 20 percent only a small part of the Sahara.

Etymology

In the ancient Egyptian language, the Sahara had the name " dscheret " ( " desert "); reproduced in the Arabic language with صحراء, DMG Sahra ' for ' desert '. Similarly, the Tuareg denote the sandy desert in the southern Sahara with Ténéré, which translates to " land out there" or " desert " is. In Arabic, the Sahara is therefore more accurate الصحراء الكبرى, DMG aṣ - Sahra 'al- Kubra, called " the (very) large desert." Sometimes you can also find the name بحر بلا ماء, DMG Bahr bila mā ʾ, " sea without water " (cf. Sahel for " shore ").

The ancient Romans called the land south of Carthage Terra Deserta for unoccupied / abandoned land. In the Middle Ages was called the Great Sahara desert plain. Only in the 19th century, the name Sahara has prevailed.

Geography

Location

The Sahara is located in North Africa. It stretches from the Atlantic coast to the Red Sea coast and approximately forms a trapezoid 4500-5500 km to the west and east from 1500 to 2000 km north- south extent. In Egypt, she is interrupted by the river oasis of the Nile. In the north, the Maghreb states of Morocco are (including the annexed territory Western Sahara, Algeria, Tunisia and Libya). South of them belong to the Sahel states Mauritania, Mali, Niger, Chad and Sudan.

Geology

Researchers conclude from the position of different rock layers that repeatedly alternated dry and wet phases over the course of several million years in this desert. By dating of fossils in soil samples from the Chad Basin was able to prove that the Sahara was at least temporarily, a desert already seven million years ago. Even still, under these analyzed soil layers found another and older sandstone layers, which could only have been caused by wind drifts under desert conditions. In the pluvial the Sahara was watered and planted, as evidenced by numerous rock paintings from the later periods and the hazards of the mountains, often more than 1000 km long dry river beds ( wadis ). Recent research at the University of Illinois at Chicago from 2004 have shown that the groundwater under Egypt and Libya up to one million years old. It flows slowly northward at a rate of only one to two meters per year in an underground system of Nubia from.

In addition, the desert is in the subtropical high pressure belt, so it is a turning circle desert. Since the descending provide air movement for cloud resolution, can take place unimpeded entry and emission of light and heat radiation.

The Sahara has a number of mountain ranges, such as the Hoggar and the Tibestigebirge. The highest peak is the Emi Koussi Tibesti with 3415 m above sea level. NN. There are also some large meteorite impact crater in the Sahara. The largest crater found so far is the Kebira Crater, it has a diameter of 31 km.

Climate

In the Sahara there is generally an arid climate. The central regions of the Sahara are all year round under the influence of the north-east trade winds, Harmattan, but of little rainfall brings. The southwestern and south central regions of the Sahara are subject to seasonal changes, which are caused by the interaction between the harmattan and the West African monsoon, while the north-western regions are dominated by the seasonal changes of the Mediterranean climate.

It can withstand extreme temperature variations occur with the daytime up to 60 ° C and at night up to 30 ° C is measured lower temperature. The average daily temperatures reach around 38 ° C in summer and in winter around 25 ° C. In the winter months can drop at night to -10 ° C, the temperature, briefly ground frost may occur and also fall snow at high altitudes. The average rainfall in the Sahara is about 45.5 mm. Generally it received the high mountains of the Sahara more precipitation than the reduction areas surrounding it. So fall in the Tibesti up to 600 mm, in the Aïr up to 150 mm annual rainfall, which form these regions own biomes. The air saturation deficit is generally very high, the evaporation rate can be up to 6330 mm in the area of ​​Ounianga lakes. During the peak of the West African monsoon in the months of July and August, falling about 100 to 200 mm of rainfall in the south of the Sahara. This gives rise to a grass savannah, which is followed by the actual Sahel. The only river that crosses the Sahara, the Nile. He is a stranger flow.

During some years it rains not in some regions of the Sahara. In other years, the West African monsoon skips the Sahara, bringing regional torrential rain with it.

The influence of the Sahara on the global climate is only partially understood. In particular, an important source of weather and climate, the aerosols from the Sahara seem to be determined aerosols next to volcanic eruptions. As a scientifically valid, that emissions have an impact on the precipitation regime in the Sahel and Sudan zone. As a very rich aerosol mobilization areas are defined as the Bodélé depression and the plateau of Djado.

Mineral resources

In the Sahara, and mineral resources are found. In the Algerian and Libyan Sahara is rich in oil and gas fields have been discovered. Other natural resources include salt, coal, copper, gold, manganese, iron, uranium, lead, tungsten, titanium, tin, and phosphates.

Population

The small native population consists mainly of Arabs, Berbers and Moors. There are also small groups like the Tubu (also Tibbu ) and Tuareg. In addition to the livestock until the 19th century, the trans-Saharan trade was a main livelihood for these communities, which are also known as Yallas. The most numerous people are the Tuareg Sahara. 60 percent of the Saharans are sedentary oasis farmers, 40 percent of nomads and semi- nomads. Larger settlements are found mainly on the northern edge of the Algerian Sahara. New settlements have formed in the oil and gas -promoting areas of Algeria and Zentrallibyens. In the west and in the Libyan desert expanse parts are deserted.

History

The Sahara was one published in 2009 study, planted in the past 200,000 years, three times for a few thousand years, at first 120000-110000 years ago and then again 50000-45000 years ago. As the tropical postponed again towards the end of the last Ice Age around 800 kilometers to the north, the Sahara, which had previously been a desert as it is today, was transformed during the so-called " green Sahara " time around 6000 years ago back in a fertile savannah landscape. This climate change followed by hunting and gathering groups living in the South. The Neolithic Revolution recognized the area of ​​the Sahara almost the same time as the sedentary groups on the Nile, Tigris and Euphrates. About the 6th millennium BC, the inhabitants of the region began with agriculture. However, a culture cities as in the above areas is not known.

In the following millennia, large parts of the Sahara were back to uninhabitable desert, after which more and more people migrated to the fertile Nile valley now. In the 2nd millennium BC, the horses time began, so named because from this time prevail horses in the motives of the cave painting. Just as in Egypt, Anatolia and the Aegean was BC the " silver bullet" to the Bronze Age, the chariot introduced in the 16th century. Pharaoh Ramses III. lists 92 chariots and 184 horses as spoils of his Libyan campaign.

With the drying of the Sahara came the slow decline of agriculture and animal husbandry. Due to the Assyrian conquest of Egypt in the 7th century BC was the camel to Africa and solves the horse as the main beast of burden from. Ever since the Ptolemaic period it was used to a greater extent.

In the center of the Sahara originated from the 5th century BC, the kingdom of the Garamantes, based on the successful oasis economy on the one hand, its great wealth but from trade between Africa and the Mediterranean, first with the Greeks about Cyrene, then by the Romans to Leptis Magna was based. The decline of the Western Roman Empire stopped this trade largely, and the depletion of groundwater resources limited the oasis economy. But the end was conquered by the Muslim Arabs.

The exploration and conquest of the Sahara

From the late 18th century, the Sahara came to the fore of European science and Export Trade. Above all, the British were looking for a safe access to the markets of Central Africa, where they tremendous market opportunities for their finished products, but at the same time hoped also important sources of raw materials. The most important of these research expeditions led the missionary James Richardson, who, however, died in 1851 in Sudan. His successor as leader of the expedition joined his companion, the German geographer and archaeologist Dr Heinrich Barth (1821-1865), at whose five -volume book of travels is the most important source for the ethnology of the Sahara area in the 19th century and still in use by the scientific is used profitably. Barth's research among the Tuareg of the northern Sahara were continued by the Frenchman Henri Duveyrier ( 1840-1892 ).