Atacama Desert
South America’s Atacama Desert is dry. It’s the second driest desert in the world, after the McMurdo Dry Valleys of Antarctica. 20 million years ago it became a desert, and the Andes mountains help keep it that way. A lot of people consider death Valley California the height of dry desert. 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. A number of land features and weather factors converge in this unique location. The first, of course, is those Andes. Atacama sits in the Andes rain shadow, which is the side of the mountain downwind of prevailing winds. On the opposite side moist air drops a great deal of rainfall. But the air is bone dry when it tops the mountain. It’s not only the Andes, the Chilean coast range on the other side does much the same thing. The anticyclone in the Pacific, a reverse spin area of very dry air, contributes on top of the rain shielding mountains.
The results are startling. 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. Any questions? 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 Atacama Desert does gain some fame from its dry conditions. The soil and overall conditions are very similar to what it’s like on Mars. In fact, it’s been a stand in for Mars in many movies including documentaries and fiction. 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. What was the verdict? Like Mars, the Atacama Desert had no life. So scientists now use this desert to prepare future tests for the red planet.
Next time you’re thirsty, consider life in the Atacama Desert. Drinks are not served there. The good news is you can’t pay for drinks that don’t exist.