Facts about Sahara desert
Sahara is the largest desert on Earth after Antarctica! The limits of the Sahara Desert are the Atlantic Ocean on the West, the Atlas Mountains. and the Mediterranean Sea in the North. The Red Sea and Egypt on the East, and the Sudan and the valley of the Niger River. in the South. The boundaries, however, are not clearly defined, and have been shifting for a thousand years. The Sahara was once a fertile area; millet and other grains were cultivated there over 8000 years ago. As conditions progressively became drier, however, and desertification set in, farmers abandoned their land. Geographically distinct is the West Sahara, which is sometimes called the Sahara Proper; the central Ahaggar Mountains and the Tibesti Massif, are plateau regions. The camel was introduced to sahara probably in the first century. The first European explorers to travel in the Sahara were Friedrich Horneman in 1805 and Mungo Park in 1806. Dust from the Sahara has occasionally been carried as far afield as the UK and Germany. The Sahara Desert accounts for around 8 per cent of the world's land area. There are an estimated 1,200 species of plant to be found in the Sahara. In the last 50 years the Sahara has spread south to cover an extra 65 million hectares. The Libyan Desert is in the East. The West Sahara Desert is an area of rock-strewn plains and sand deserts of varying elevation. The land is presently almost entirely without rainfall or surface water but possesses a number of underground rivers that flow fast from the Atlas and other mountains. Occasionally the waters of these rivers find their way seeping to the surface; in these naturally irrigated oases, plants grow freely. The soil of this region of the Sahara is highly fertile and, where irrigation is possible, produces excellent crops. The central plateau region of the Sahara Desert runs for about 1600 km, about 1000 miles in a Northwest to Southeast direction. The plateau itself varies in height, from about 600 to 750 m (about 1900 to 2500 ft). Peaks in the several mountain ranges that rise from the plateau are from about 1800, to more than 3400 m (about 6000 to more than 11,200 ft) high. Notable peaks include Emi Koussi (3415 meters/11,204 feet), in the Tibesti Massif, and Tahat (3003 meters / 9852 feet), in the Ahaggar Range. Although rainfall is scant in the area, several of the central Saharan peaks are snow-capped during part of the year. The Libyan Sahara Desert is considered the most arid part of the Sahara. Moisture is almost totally absent and few oases exist. The land is characterized by sandy wastes and large dunes of sand 122 meters (i.e 400 feet) or more in height. The valley of the Nile River and the mountainous area of the Nubian Desert to the East of the Nile are geographically, part of the Sahara. However, the irrigation afforded by the Nile transforms the desert into fertile agricultural land throughout much of Egypt. The boundaries, however, are not clearly defined, and have been shifting for a thousand years.The limits of the Sahara Desert are the Atlantic Ocean on the west, the Atlas Mountains and the Mediterranean Sea in the North, the Red Sea and Egypt in the east, and the Sudan and the valley of the Niger River in the south. The central plateau region of the Sahara Desert runs for about 1600 km, about 1000 miles in a Northwest to Southeast direction. The plateau itself varies in height, from about 600 to 750 m (about 1900 to 2500 ft). Peaks in the several mountain ranges that rise from the plateau are from about 1800, to more than 3400 m (about 6000 to more than 11,200 ft) high. The Sahara has one of the harshest climates in the world. Located in the trade winds belt, the region is subject to winds that are frequently strong and that blow constantly from the northeast between a subtropical high-pressure cell and an equatorial low-pressure cell. As air moves downward from the high-pressure into the low-pressure cell, it becomes warmer and drier. The desiccating and dust-laden winds are sometimes felt north and south of the desert, where they are variously known as sirocco, khamsin, simoom, and harmattan. The northern slopes of the Atlas Mts. intercept most of the moisture from winds blowing inshore from the Mediterranean Sea. Border zones on the north and south, where the desert merges with the steppe, receive about 10 in. (25 cm) of rain a year with some seasonal regularity, but over most of the region rainfall is sparser, with an average annual total of less than 5 in. (12.7 cm); rainfall is usually torrential when it occurs after long dry periods that sometimes last for years. The region's low relative humidity rarely exceeds 30% and is often in the 4% to 5% range. Daytime temperatures are high; Azizia, Libya, recorded the world's highest official temperature in the shade (136°F/58°C) in September, 1922. Heat loss is rapid at night and a diurnal range of 86°F (30°C) is common. Freezing temperatures are quite common at night from December to February. |
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