|MadSci Network: Earth Sciences|
Earth's hydrologic cycle was reported in a 1989 Scientific American article (J.W.M. laRiviere, 261 (3), 80-94), which I will summarize here. Evaporation takes place over the oceans and continents. Over the oceans, this amounts to 425,000 cubic kilometers per year. Over the continents, evaporation takes place from bodies of waters like lakes and rivers, but also directly via transpiration from plants and animals. Collectively, continental evapotranspiration amounts 71,000 cubic kilometers per year. This gives us a total of 496,000 cubic kilometers of water evaporated/transpirated from the oceans and continents per year. To answer your question, roughly 1400 cubic kilometers (1.4 x 10^15 liters) of water is evaporated each day on earth. To put this in perspective, this is about 10,000 times the amount of water consumed by the United States per day.
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