When did humans first learn of the water cycle?

Question

When did humans first learn of the water cycle?

Answer 1

Please read the content of this link. It might be a little help

http://theory.uwinnipeg.ca/mod_tech/node...

Wiki has good description about the subject matter

http://en.wikipedia.org/wiki/Hydrosphere

And here is about the ice age..........

http://en.wikipedia.org/wiki/Ice_age

And finally this link seems to me awesome

with all the details you might need

http://www.carleton.edu/departments/GEOL...