Filling nearly all of northern Africa , it measures approximately 3, miles 4, km from east to west and between and 1, miles from north to south and has a total area of some 3,, square miles 8,, square km ; the actual area varies as the desert expands and contracts over time. The Sahara is bordered in the west by the Atlantic Ocean , in the north by the Atlas Mountains and Mediterranean Sea , in the east by the Red Sea , and in the south by the Sahel —a semiarid region that forms a transitional zone between the Sahara to the north and the belt of humid savannas to the south. The southern reaches of the Sahara end in the Sahel , a semiarid buffer zone that separates the desert from the more temperate savanna biomes beyond. Some scientists estimate that the Sahara became arid about two to three million years ago, while others contend that it happened before this. Though boasting an extremely low primary productivity, the Sahara does manage to support some life. Many of the organisms that can survive have been able to do so with adaptations for arid environments: for example, many herbaceous plants found in the Sahara are ephemerals , meaning that almost all of their life cycle—from germination to seed dispersal—occurs in the two- to three-week period after a heavy rain. Animals such as the desert snail survive by using estivation, a period of dormancy that some animals can enter when encountering extreme environmental stress. Other organisms, although adapted more for a Mediterranean or tropical climate than an arid one, have persisted in the Sahara mostly by sticking to its slightly more hospitable highlands and oases. People have lived in the Sahara long before recorded history, at certain times in regions that are now too arid for human inhabitance.
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Landscape Water Climate. Blanketing much of the northern third of the African Continent, or some 3. The Sahara Desert impacts almost all of the countries of northern Africa. The Sahara's topographical features, said "The Living Africa," include not only the iconic sand dune fields, but also arid mountains, plateaus, sand- and gravel-covered plains, shallow basins and large oasis depressions. Its highest point is Chad's Mount Koussi an extinct volcanic crater that rises 11, feet above sea level at the peak , and its lowest, Egypt's Qattera Depression an oasis depression that lies feet below sea level at the deepest point. The Sahara's fabled dune fields, which cover only about 15 percent of the entire desert's surface, lie primarily in the north central region, in the countries of Algeria and Libya. Most sand dunes -- mounds and ridges of sand sculpted by wind and gravity -- have a windward or "backslope" surface and a leeward or "slipface" surface. Prevailing winds drive sand up the backslope until it reaches a crest and then collapses under the pull of gravity, cascading down the slipface. The wind may leave rippled surfaces in its wake.
The Sahara Desert is the world's largest hot desert and the third largest desert behind Antarctica and the Arctic. Located in North Africa, it covers large sections of the continent - covering 9,, square kilometers which is comparable to the are of China or the US! The Sahara is the hottest desert in the world — with one of the harshest climates. The area receives little rainfall, in fact, half of the Sahara Desert receives less than 1 inch of rain every year.