The Driest Place in the World
Spanning some 41,000 square miles across four South American countries, the Atacama Desert is considered the driest place in the world. In Chile, the desert receives just 0.004 inches of rain per year, though snowmelt from the nearby Andes Mountains fills lakes and rivers that support wildlife. (Ross Huggett/flickr)
Four inches of rain – every one thousand years.
That's how dry it is in South America's Atacama Desert, which stretches some 600 miles between Peru's southern border and Chile's central Pacific coast.
Years often pass without a single drop in the desert's central region, a place some researchers believe may have seen no significant rainfall for 400 years, between the 1570s and the early 1970s. Here you won't find a single living thing – no animals and not a single cactus, hardscrabble weed or even a blade of grass.
Rain almost never falls here thanks to the Andes and Chilean Coast mountain ranges, which block clouds from moving across the 41,000-square-mile desert from the east and west, respectively. The Humboldt Current, swirling just offshore in the Pacific, also creates an inversion layer of cool air that keeps rain-producing clouds from forming here.
Satellite view of the Atacama Desert.
Amazingly, more than a million people live in the Atacama. Many live near and work at copper mines in the desert, while others live along the coast or work at research stations like the Paranal Observatory, where astronomers use the Very Large Telescope to peer deep into space on the more than 300 clear nights a year here.
What exactly is life like in one of Earth's most extreme environments?
People get drinking water from the air. Marine fog blowing in from the Pacific is the only way that some parts of the Atacama plateau receive any precipitation. Called "camanchaca," this fog provides enough water to support some plant life in the desert. Local villagers even use specially-made fog "nets" to capture water from the air, using screens on which the fog condenses and drips into collecting troughs.
Cooler temperatures prevail. Unlike many other deserts where scorching heat is the norm – like California's Mojave Desert and the Sahara Desert of northern Africa – average daytime temperatures in the Atacama range between 32 and 77 degrees Fahrenheit, and can fall to as low as 10 to 15 degrees below zero at night.
Snow, though rare, sometimes falls. In July 2011 (winter in the Southern Hemisphere occurs in June, July and August), an extreme cold front brought more than 30 inches of snow to the Atacama plateau, stranding drivers in snow drifts in Bolivia. It was the first time the region had seen this much snow in nearly 20 years.
There's a giant hand out there. About 70 miles south of the coastal city of Antofagasta, the long highway through the desert is interrupted by a 36-ft.-high sculpture of a giant hand reaching up from beneath the desert floor. Opened to the public in 1992, the sculpture today has become a must-stop-and-see for tourists (and vandals, as its base is often covered in graffiti).
Penguins the size of people once lived here. About 36 million years ago, penguins that stood 4 1/2 feet tall roamed the region we know today as the Atacama, according to researchers who discovered fossilized skulls of the giant flightless birds in the desert back in 2007, National Geographic reports.
Active geyser fields are open to tourists. The El Tatio geyser field lies along the edge of the Atacama in northern Chile, where you can walk right up to columns of hot steam ejecting from the ground. Tourists are warned to use extreme caution, as parts of the geyser field can reach boiling-level temperatures.
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Mount Waialeale, Kauai, Hawaii
Once believed to be the wettest place on Earth, Hawaii's Mount Waialeale (its name in Hawaiian means 'rippling water') averages more than 450 inches of rain each year. Depending on which source you trust, rain falls on the 5,148-ft.-high peak between 330 and 360 days each year. Photo by Scott/flickr