|MadSci Network: Earth Sciences|
The amount of water vapor content in the atmosphere is ever-changing due to constant evaporation and precipitation across the globe. Some recent studies indicate that the amount of water vapor is increasing due to warmer air temperatures, resulting in a greater capacity of the air to hold additional water vapor.
It is estimated that if all the water vapor in the atmosphere were to condense and fall as rain, that it would amount to a depth of only about 2.5 centimeters.
For more information, read this report entitled "Water Vapor in the Climate System".
Try the links in the MadSci Library for more information on Earth Sciences.