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The Driest Place on Earth: the Atacama DesertIn some spots it has not been raining for at least 500 years! |
By Stefan Anitei, Science Editor
23rd of May 2007, 15:33 GMT
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The Atacama Desert is located in northern Chile and reaches a small part of southern Peru (South America), climbing up to 3,200 m (10,670 ft) altitude on an area of 181,300 square km (72,500 square mi). It spreads like a rather narrow stretch between the Pacific Ocean and the Andes mountains over a distance of 960 km (600 mi) off the both sides of the Tropic of Capricorn, presenting strong contrasts: stony hills, volcanic rocks and sand dunes.
A high pressure cell over the Pacific keep back moisture from the west, while the mountains block clouds formed in the Amazon Basin from the east.
On the coast, the cold water Peru Current coming from Antarctica chills the desert air, further inhibiting the rain clouds.
The average annual rainfall is about one inch (25 mm) and in some mid-deserts spots, rain has never been recorded, at least as long as humans have measured it.
Not even cacti grow there. The air is so dry that metal objects never oxidize and the meat left for long on open air preserves for unlimited time. Without moisture nothing rots.
It is so arid, that mountains that reach as high as 6,885 metres (22,590 feet) lack glaciers and, in the southern part from 25°S to 27°S, have possibly been glacier-free throughout the Ice Age. Travellers relate that during summer the drought is so severe that hair and beard crumble and fall and the nails chap.
Near the sea a dense fog called camanchaca flows thick. When the stable high-pressure cell offshore traps cool ocean air against the hillsides, the air condenses into low-lying clouds, the camanchaca.
The chamanchaca is not wet enough to produce rainfall but does provide for an opportunistic ecosystem high above the shore: moss-covered cacti, shrubs, certain rodents and foxes. Curiously, but in Atacama there are about 1 million people living in coastal cities, mining settlements, fishing villages and oasis towns.
People even make agriculture in Atacama, using the water of the aquifers, which are fuelled by snowmelt from the Andes.
The main richness of Atacama was represented by the enormous deposits of Chile saltpeter (sodium nitrate), unique in the world (in the ancient Egypt, saltpeter was used for embalming the mummies). Now, in Atacama copper, silver, gold and iron are mined.
The name of this desert seems to come from the native Atacama Indians, who still inhabit the area. Another thing: Atacama harbors one of the largest astronomic observatories, the Very Large Telescope, as here is one of the clearest skies on Earth to look at the stars.
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