The Driest Place on Earth: Chile's Atacama Desert

The Atacama Desert, also known as Desierto de Atacama in Spanish, is nestled between the Pacific Ocean to the west and the Andes Mountains to the east. Its northern border touches southern Peru, while its southern side extends into Chile, reaching toward the country's port city of Antofagasta.

Within this expanse lie several distinctive features, including the Atacama Salt Flat, the Pampa del Tamarugal (Plateau of the Tamarugal) and two famous dry valleys near the town of San Pedro de Atacama: Valle de la Luna (Valley of the Moon) and Valle de Marte (Mars Valley).

People compare the Atacama to Mars because the surface of the red planet features a similar climate and terrain. Another common name for Mars Valley is Valle de la Muerte, or Valley of Death.

The desert floor of the Atacama is marked by barren, otherworldly landscapes, with vast stretches of sand and rocky terrain. Unlike other deserts that may feature occasional oases or scattered vegetation, the Atacama Desert is characterized mainly by how stark and desolate it is.

The elevation varies throughout the region. For example, San Pedro de Atacama is around 8,000 feet (2,438 m) above sea level, but some higher areas exceeding 16,000 feet (4,877 m).

The Atacama Desert is defined by its extreme aridity. The combination of cold air from the Peru Current (also known as the Humboldt Current) in the Pacific Ocean and the hot desert air creates a unique weather pattern. The cold ocean currents cool the air, causing it to lose its moisture. Then this dry air sweeps across the coastal areas and inland toward the desert.

The Atacama receives almost no water from precipitation, with some parts of the region having not received rain in centuries, making it the absolute driest place on Earth.

This lack of precipitation is due to the high altitude of the Andes Mountains, which block seaward-flowing ice from reaching the desert, as well as katabatic winds (high-density air pulled downward by gravity) that descend from the mountains, further drying the air.

You might assume the Atacama Desert would be blistering hot due to its extreme dryness, but that assumption would be false. The average summer temperature in Antofagasta, a major port city in northern Chile is a relatively intermediate 65 degrees Fahrenheit (18 degrees Celsius).

Despite its reputation for extreme dryness, the Atacama Desert is not entirely devoid of moisture.

Along the coast, a phenomenon known as the camanchaca occurs: a dense marine fog from the Pacific that blankets the desert. While it doesn't produce any rain, the camanchaca does provide a minimal source of moisture for certain plants and animals.

Despite its harsh conditions, the Atacama Desert is home to a surprising array of wildlife and plant species.

Along the coast and in the valleys, you can find hardy cacti, succulents, flowers and herbs that have adapted to the arid environment. These plants play a crucial role in providing a habitat and food for the desert's animal inhabitants, including foxes, birds, rodents and reptiles.

The desert's prominent salt flat, Salar de Atacama, is located in the southern part, where unique microorganisms thrive in the briny waters. These microorganisms serve as a source of food for flamingos, which flock to the country's largest salt deposit in the summer, adding a splash of color to the barren landscape.

However inhospitable the Atacama Desert may seem to some, it's a home to more than 1 million people. Throughout history, the region has seen the exploitation of its natural resources, including rich nitrate deposits (also called saltpeter deposits), which businesses mined extensively during the 19th and early 20th centuries.

The mining industry brought wealth and development to the region, but it also left behind scars on the landscape and created conflicts between Chile and Bolivia, both of which were vying for the area's natural resources.

Today, the Atacama Desert continues to be a site of interest for scientists and researchers from all around the world. Its unique conditions make it an ideal location for studying life in extreme environments, while its lack of light pollution or precipitation make it a perfect place to observe the night sky.

The Atacama is currently home to the Atacama Large Millimeter Array as well as the Extremely Large Telescope (ELT), and there have been numerous past astronomy projects in the region.

The Atacama Desert has the distinction of being the driest place on Earth, but there are a number of other places that are similarly (but not quite as) arid. It may come as no surprise that the driest regions on the planet are typically deserts, where precipitation is extremely scarce.

1. McMurdo Dry Valleys

Although the McMurdo Dry Valleys in Antarctica feature a landscape covered in ice and frozen soil, this polar desert also has extremely low humidity and experiences almost no rainfall. Situated west of McMurdo Sound, the area has an average annual temperature of minus 4 degrees Fahrenheit (minus 20 degrees Celsius) and an annual total precipitation just under 2.5 inches (6 cm).

McMurdo Sound is famous for being a base to British explorer Ernest Shackleton, who wintered there while trying to reach the South Pole between 1907 and 1909. His hut still stands there.

2. Sahara Desert

Located in North Africa, the Sahara is the largest hot desert in the world, with high temperatures regularly reaching 122 degrees Fahrenheit (50 degrees Celsius) during the hottest months. It stretches from the Atlantic in the west to the Mediterranean Sea in the north to the Red Sea in the east.

The desert receives an average of 3 inches (7.6 cm) of rainfall per year, with most of that occurring between December and March. Despite its extreme climate, about 2.5 million people live in the Sahara.

3. Sonoran Desert

Located in southwestern North America, the Sonoran stretches across parts of the United States and Mexico. In the area near the lower part of the Colorado River, the temperature can climb to 120 degrees Fahrenheit (49 degrees Celsius) in the summer, and the average rainfall doesn't exceed 3 inches (7.6 cm).

Common vegetation there includes various cactus plants, including saguaros, as well as mesquite trees and creosote bushes.

4. Arabian Desert

Stretching across much of the Arabian Peninsula in the Middle East, this tropical desert is a land of extremes. The region experiences extremely high temperatures, sometimes as intense as 130 degrees Fahrenheit (55 degrees Celsius).

While its annual rainfall can swing between nothing and as much as 20 inches (51 cm), on average, it receives less than 4 inches (10.2 cm) per year. Dust storms and torrential floods occur periodically, adding to the harsh environment.

5. Namib Desert

Considered to be one of the oldest deserts in the world, the Namib in southern Africa has experienced hyper-arid conditions for millions of years. Situated along Africa's western coast, the area receives very little rainfall, with inland areas receiving maybe 2 inches (5 cm) annually and the regions along the coast averaging half an inch (1.3 cm) per year.

Very few people live here, although inland, you can find elephants, rhinoceroses, lions and other mammals.

This article was created in conjunction with AI technology, then was fact-checked and edited by a HowStuffWorks editor.