Altiplano

The Altiplano, meaning "high plain" in Spanish, is a vast high plateau in west-central South America. It is the largest high plateau on Earth outside of Tibet. Most of the Altiplano is in Bolivia, but parts also stretch into Peru, Chile, and Argentina.

Many towns and cities, such as El Alto, Oruro, Juliaca, and Puno, are located on the Altiplano. The northeastern area gets more rain, while the southwestern part is very dry and has large salt flats called salares. The famous Lake Titicaca, the largest lake in South America, sits on the border of Bolivia and Peru. Another lake, Lake Poopó in Bolivia, dried up completely by December 2015.

Long ago, many important cultures, like the Chiripa, Tiawanaku, and the Inca Empire, lived on the Altiplano. Later, Spain conquered the area in the 16th century. Today, people make a living by mining, raising animals like llama and vicuña, and providing services in the cities. The Altiplano also draws visitors from around the world.

Geography

The Altiplano is a high, flat area in the central Andes mountains. It covers parts of northern Chile, western Bolivia, southern Peru, and northwest Argentina. The land here sits about 3,750 meters (12,300 feet) above sea level, making it very high but a little lower than the Tibetan Plateau.

The area has many tall, active volcanoes, like Ampato, Tutupaca, and Illimani. To the southwest lies the Atacama Desert, one of the driest places on Earth, while the wet Amazon rainforest is to the east. Because of the height, the air here can be hard to breathe. People who live in the Altiplano include the Qulla, Uros, Quechua, and Aymara.

Geology

See also: Altiplano Basin, Geology of Bolivia, and Altiplano–Puna volcanic complex

Scientists have several ideas about how the Altiplano plateau formed. One idea is that weaknesses in the Earth’s crust allowed the land to rise in certain areas. Another idea is that heat from deep within the Earth helped lift the land upward. Climate also played a role by shaping where water flowed and settled, which affected how the land moved.

During a time called the Pleistocene, huge lakes covered parts of the Altiplano. Today, these lakes have mostly dried up, leaving behind large salt flats. Remnants of these ancient lakes include Lake Titicaca, which sits on the border of Peru and Bolivia, and Poopó, a salt lake south of Oruro, Bolivia. Two big dry salt flats, Salar de Uyuni and Salar de Coipasa, are what remain after these old lakes dried out.

Climate

Further information: Rainy season in the Altiplano

The Altiplano is a very high area, with an average height of more than 3,800 meters above sea level. Because of this height, the weather there is cold and dry. The temperature can change a lot from day to night. Scientists say this height makes the climate colder than areas known as tierra fría but not as cold as tierra helada, which starts around 4,500 meters or 15,000 feet high. Other names for this high area include puna and páramos.

The weather here is usually cool and can be dry or a little wet, becoming very dry in some places. The average temperature each year changes from about 3 °C (37 °F) near the western mountains to around 12 °C (54 °F) near Lake Titicaca. How much rain falls each year changes too—from less than 200 mm (8 in) in the southwest to more than 800 mm (31 in) near and above Lake Titicaca. The temperature can swing widely in a single day, with the hottest part reaching 12 to 24 °C (54 to 75 °F) and the coldest dropping to between −20 °C and 10 °C (−4 °F to 50 °F).

The coldest weather happens in the southwest part of the Altiplano during the winter months of June and July. Rain mostly falls between December and March. The rest of the year is usually very dry, cool, windy, and sunny. Snow can sometimes fall between April and September, especially in the north, but it does not happen often—usually only one to five times each year.

Lake Titicaca and the Amazon Basin affect the humidity and temperature in the area. The north and west tend to be more humid than the south and east. Lake Titicaca helps control the temperature on the Collao Plateau. Because the lake is large, it absorbs heat during the day and releases it at night. This makes the temperature changes smaller and creates milder weather near the lake, which helps plants grow and people live there.

Panorama of Peruvian Altiplano.