Why is there the Altacama desert in Chile? It is one of the driest. It is not tropical. Why?

Question

It seems like that it should be wet and rainy. It came up in The seventh grade social studies class that I teach.

Answer 1

Because all the moisture in the clouds has condensed and fallen as rain over the Amazon before it has reached the desert. The predominant wind direction is easterly, moist air over the ocean is driven inland, over the Amazon towards the Andes. The clouds have lost all their rain before they get there. That's why the amazon is wet and the Andes is dry.