If you’re looking for dry places in the world, look no further than the Atacama Desert. It’s the second driest desert in the world, after the McMurdo Dry Valleys of Antarctica. It’s been a desert for over 20 million years, kept that way by the Andes Mountains which block rain from reaching the area. Some people think Death Valley in California is dry. But that area is 50 times wetter than the Atacama Desert.
It takes more than just one mountain range to maintain the amazing Atacama Desert. The weather and other geographic features play a role. The first, of course, is those Andes. Atacama is in this mountain range’s rainshadow, an area of a mountain downwind of the general prevailing winds. This means that when winds and moist air hit the mountain on one side, that air condenses into a lot of rain. But that leaves the air dry as it tops the mountain and proceeds to the other side. As if that’s not bad enough, the Chilean coast range is responsible for the same effect on the opposite side of the desert. The anti-cyclone, reverse spin area of dry air over the Pacific, multiplies the effect.
Dry means dry. Rain falls in the Atacama Desert to the tune of only about 1 mm every year. Some areas never receive rain. It’s fairly well accepted that from 1570 to 1971, no rain fell at all. Do you believe it’s dry? Can there be a drought in an area that received less rain in a year than a thimble would hold? There are some river beds in the desert that haven’t held any water for at least 120,000 years.
The super dry dry does lend the Atacama Desert some fame and fortune. It’s considered the closest to Mars like conditions that exist on Earth. Many movies and documentaries about Mars have been filmed in this desert. In 2003 some scientists decided to conduct the same tests that the Mars landers, Viking 1 and Viking 2, had conducted on the red planet. The tests were created to search for life. Can you guess the results? Like Mars, the Atacama Desert had no life. So scientists now use this desert to prepare future tests for the red planet.
When you drink a glass of water think about the Atacama Desert. Drinks are not served there. In one of the driest places on Earth it could be years before you could even fill a small glass with water.
Posted on February 25th, 2009 by Admin
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