The Great Atacama Desert
The Atacama Desert covers a total area of 40,541 sq. mi (105,000 sq. km), stretching 600mi (1000km) from southern Peru into northern Chile. Officially the driest place on Earth, the Atacama Desert receives almost no rainfall whatsoever. In fact, it is so dry that some weather stations in the desert have never recorded a single drop of rain. As a result of these harsh conditions, plant and animal life is almost non-existent, particularly in the lower Atacama Desert. The northern coastal areas, however, do receive a little more rainfall, and as a result, are less arid.
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Reasons why the Atacama Desert is so dry
There are three main reasons that contribute to the Atacama Desert being the driest place on earth. The first reason is that the desert sits on the wrong side of the Andes with regards to prevailing winds. The prevailing southeast trade winds that carry moist air are forced to rise. The moisture condenses, and falls on the opposite side of the Andes to the Atacama. This is commonly known as a rain shadow.
The second reason is the high air pressure in the Atacama Desert. Essentially, descending air warms up, meaning that any moisture within turns to water vapor (gas, not liquid) as opposed to rain.
The third and the last reason is the cold Humboldt Current from the Pacific Ocean. Any onshore winds are usually chilled so they are unable to pick up moisture from the ocean. Cumulatively, the effect of the aforementioned three points creates the driest place on earth…The Atacama Desert.
Atacama Desert Temperatures
The Atacama Desert is pretty cold despite being the driest desert and the temperature ranges between 0°C to 25°C. The annual rainfall in this dry desert area is less than 0.004 inches/0.01cm of rain per year. Since the desert lies between Andes Mountain in the east and Chile coast to the west, this region has rain shadow effect and is deprived of almost all moisture.
Flora in the Atacama
Plants do not grow in this region as the desert is covered with marine fog. However, some species of cacti, algae, and lichen are found.
Animals That Live in the Atacama Desert
Birds are probably the largest animal group in the Atacama Desert. Humboldt penguins live year-round along the coast, nesting in desert cliffs overlooking the ocean. On salt flats both near the Pacific and inland, Andean flamingos flock to eat the algae. Other birds, including species of hummingbirds and sparrows, visit the desert seasonally to feed on insects, nectar, seeds and flowers. The Atacama helps sustain several threatened species, such as the Tamarugo Conebill, the Chilean Woodstar and the Slender-Billed Finch. When flowers are in bloom, the deserts’ ecosystems even support birds of prey, such as burrowing owls and Chimango Caracaras.
Because of the desert’s extreme aridity, only a few specially adapted mammal species live in the Atacama. Darwin’s leaf-eared mouse eats grass, insects and seeds. The South American gray fox, also omnivorous, lives on eggs, fruit, lizards, rodents, seeds and even scorpions. The viscacha, a relative of the chinchilla, also lives in parts of the desert. Larger animals, such as guanacos and vicunas -- both relatives of llamas -- graze in areas where grass grows, irrigated by melted snow. Vicunas need to remain near a steady water supply, while guanacos can roam into more arid areas and survive longer without fresh water. Fur seals and sea lions often gather along the coast.
Reptiles and Amphibians
The Atacama Desert has surprisingly few reptile and amphibian species. The Vallenar toad lives on the desert, where it lays eggs in permanent ponds or streams. Iguanas and lava lizards inhabit parts of the desert, while salt flat lizards live in the dry areas bordering the ocean.
Insects and Arachnids
Many parts of the Atacama Desert are too dry to sustain even insect life. In other areas, sand-colored grasshoppers blend with pebbles on the desert floor. Beetles and their larvae provide a valuable food source in the desert. Desert wasps sometimes prey on other insects. During especially warm, humid seasons, butterflies visit the desert. Red scorpions also live in the desert, where their color helps conceal them from predators such as gray foxes.