An Explanation of the Water Cycle (with Pictures and Diagrams)
What makes the water cycle work?
It's not a perfectly linear cycle; the same water molecules don't go through the four cycles at the same speed, or spend the same amount of time in each one. As it turns out, much more water is "in storage" -- frozen in glaciers, sitting in lakes or reservoirs, or underground aquifers -- than is actually moving through the cycle, and most of it -- 95% of the world's water supply, actually -- is stored in our planet's oceans.
Because of global warming, the water cycle will continue to intensify during the 21st century, according to the Intergovernmental Panel on Climate Change; notably, though, this doesn't mean increased precipitation across the board. In places where it's already dry, it's going to get drier, increasing the probability of drought.
Glacial retreat is another water cycle-related consequence of a warming globe; as the temperature rises, the supply of water to glaciers from precipitation cannot keep up with the loss of water from melting and sublimation. When it rains, it pours, so to speak.
For further water cycle-relating reading in TreeHugger, check out Dumb Question Dept.: If Earth is a Closed System and We're Running Out of Water, Where's it All Going?, Water Running Out in Atlanta and our How to Green Your Water guide. Elsewhere the USGS has a good intro and Wikipedia covers the basics as well.
Quench your thirst for more green knowledge with our Green Basics column, which appears Thursdays here at TreeHugger.