It rains in the Amazon because the trees want it to. There is plenty of moisture in the oceans that surround the continent, but there is also a hidden reservoir on the land feeding an invisible river that flows upward to the sky. The water held in the soil is lifted up by the bodies of the trees and lost through the surfaces of their leaves to the atmosphere. The local sky plumps with moisture, primed for the arrival of the seasonal rains driven by the annual back-and-forth march of the sun’s rays. As climate scientist Alex Hall puts it, the trees are co-conspiring with the sky to attract an earlier monsoon.
