Calama is a city and commune in the Atacama Desert, Northen Chile, Calama is one of the driest places on earth with an annual precipitation of just 5 mm (0.20 in) the only source of water for irrigation is from The River Loa.
So why does it not rain in Calama ?
The Atacama Dersert stretches 600 miles between Peru's southern border down to Chile's central Pacific coast, and the whole area is protected by the Andes Mountains and Chilean coastal mountain ranges, this blockade prevent rain clouds from moving across the area thus resulting in very little to no rain all year round.
However, some regions of the desert do receive moisture from melted snow runoffs that comes from the Andes Mountain but that only amounts to 0.004” per year.
Calama current weather
compared to
Chile's capital, Santiago