Chile's Atacama Desert is one of the driest places on Earth. Rainfall in much of this desert averages less than 1 millimeter (0.04 inch) per year! Click on image for full size (58 Kb) Image courtesy of NASA.

Chile's Atacama Desert is one of the driest places on Earth. Much of the desert receives less than 1 millimeter (0.04 inch) of rainfall per year on average, making it 50 times more arid than California's Death Valley.

As you might guess, few people live in this extreme environment. Likewise, there are hardly any animals, plants, or even microbes in the Atacama Desert. The area is not totally uninhabited, though. Some people and other living creatures do manage to survive in the harsh environment of the Atacama.

The Atacama Desert extends from a place near the Chile-Peru border in the north to roughly 30° south latitude, a distance of about 1,000 km (600 miles). It covers an area of 140,000 km² (54,000 square miles), which is about the size of the state of New York in the U.S.A. Much of this desert lies at high elevations.

The Atacama is the driest hot desert in the world; only Antarctica's Dry Valleys are more arid. Some weather stations in the Atacama have never received any rain. One scientist estimated that rain typically falls but once per decade in the driest, central portion of the desert.

Why is the Atacama so incredibly dry? To begin with, this desert is located in the "rain shadow" between two mountain ranges, the Andes and the Chilean Coast Range. Winds in the area, generated by a large-scale atmospheric flow called the Pacific Anticyclone, are very dry. The air is descending, as part of a large flow of air called the Walker circulation, and the descending air is especially dry. The Humboldt Current (also called the Peru Current) carries cold water northward along the western coast of South America. This cold ocean current cools the air above it, which reduces the amount of moisture the air can hold. This mix of mountains, winds, and ocean currents combines to make the Atacama incredibly dry.

Besides being arid, the Atacama is one of the oldest deserts in the world. Scientists estimate that parts of it have been dry for at least 20 million years and possibly as long as 40 million years. This is much older than other hyper-arid regions, such as the Dry Valleys of Antarctica (10-11 million years) and the Namib Desert in Africa (5 million years). Some dry river beds in the Atacama haven't had water flowing in them for 120,000 years!

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 (58 Kb) Image courtesy of NASA.

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!

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 (58 Kb) Image courtesy of NASA.

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, this desert gets less than 1 millimeter (0.04 inch) of rain!

It is hard to survive in the Atacama Desert. Hardly any people, animals, plants, or even microbes live there. But there are some people and other creatures living in the Atacama.

The Atacama Desert starts in northern Chile. 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!

Why is the Atacama so dry? First, this desert is in between two mountain ranges, the Andes and the Chilean Coast Range. The mountains keep out most rain clouds. Second, the winds near the Atacama are also very dry. A big air current in the area, called the Walker circulation, carries air downward. The air that is moving downward is very dry. Third, 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 as warm air. This mix of mountains, winds, and ocean currents combines to make the Atacama incredibly dry.