Why the Atacama Desert Is the Driest Non-Polar Place on Earth

Four reinforcing mechanisms create the Atacama's extreme aridity:

1. Andean Rain Shadow: Prevailing easterly winds drop moisture on Amazon-side slopes; descending air warms and dries over Atacama.
2. Cold Humboldt Current: Upwelling cools onshore air, stabilizing it, suppressing convection and rain.
3. Subsiding Air (Hadley Cell): Atacama sits under descending limb of tropical circulation; sinking air inhibits clouds.
4. Semi-Permanent Pacific High: Persistent high-pressure system blocks moisture-bearing systems.

Result: Some weather stations have never recorded rainfall; average <1 mm/year. Yet fog (camanchaca) supports specialized life.