Where is Atacama desert located, and why there is no rain there?
The Atacama desert, where the Tropic of Capricorn cuts the west coast of South America, is as dry as it is (vying with the Namibian desert on the west coast of southern Africa as the driest on Earth) because of three factors: 1) it lies on the northern fringe of the Subtropical High (pressure) of the southern hemisphere, 2) the cold Humboldt Current lies immediately offshore, and 3) the high Andes lie immediately to the east. Under the subtropical high, descending air (the return flow from upward convection of the Equatorial low and tropical rain forests) is compressionally warmed without addition of moisture – it is thus extremely dry. The relatively cool water offshore cools the overlying air, making it dense, thus stable, with few thunderstorms. [The dew and fog mentioned in a previous answer results from this basal cooling.] And finally, what regional wind flow there is is from the east, thus the rain shadow effect also mentioned previously does have an effect, reducing the flow of