Here's a question I'd never thought to ponder before: which came first, the rainforest or the rain? One would suppose there was rain before the rainforest appeared, but was it as much as a rainforest normally gets? MinuteEarth explains the cycle of water moving through a tropical forest, and what happened millions of years ago to kickstart this cycle. However, mankind is doing extensive damage to the rainforest, which is already showing signs of disrupting the water cycle that was establioshed so long ago. This may have implications for global weather in the years to come. -via Viral Viral Videos
source: http://faculty.washington.edu/dcatling/Catling2012_GreenMountainSubmitted.pdf