This picture shows the Atacama Desert in Chile. The Atacama is one of the driest places on Earth. The average rainfall for a whole year in this desert is less than 1 millimeter (0.04 inch) per year!
Click on image for full size
Image courtesy of NASA.

Atacama Desert

The Atacama Desert is one of the driest places on Earth. The Atacama is in the country of Chile in South America. In an average year, much of this desert gets less than 1 millimeter (0.04 inch) of rain! That makes it 50 times drier than Death Valley in California.

It is hard to survive in the Atacama Desert. Few people, animals, plants, or even microbes live there. But the desert isn't completely without life. Some people and other living creatures do get by in the Atacama.

The north end of the Atacama Desert is near the border of Chile and Peru. It runs about 1,000 km (600 miles) south from there. It has an area of 140,000 km2 (54,000 square miles). That is about the size of the state of New York in the U.S.A.

The Atacama is the driest hot desert in the world. There are some weather stations in the Atacama where there has never been any rain! Not all deserts are hot. The Dry Valleys in Antarctica are cold deserts. They are the driest deserts on Earth.

Why is the Atacama so dry? First, this desert is located in the "rain shadow" between two mountain ranges, the Andes and the Chilean Coast Range. Second, winds called the Pacific Anticyclone flow through this area. Those winds blow dry air into the Atacama Desert. Third, another major flow of air in this region, the Walker circulation, causes air to descend near the Atacama. This descending air is very dry. Fourth, an ocean current called the Humboldt Current (or the Peru Current) carries cold water northward along the western coast of South America. This cold ocean current cools the air above it. Cold air can't hold as much water vapor as warm air so it dries out any water left in the air. This mix of mountains, winds, and ocean currents combines to make the Atacama incredibly dry.

The Atacama is also one of the oldest deserts in the world. Scientists think parts of it have been dry for at least 20 million years and maybe as long as 40 million years. That is much older than other very dry deserts. The Dry Valleys of Antarctica are about 10-11 million years old. The Namib Desert in Africa is only 5 million years old. Some dry river beds in the Atacama haven't had water flowing in them for 120,000 years!

Last modified October 27, 2008 by Randy Russell.

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