Eyeball does make sense, though. Cause when your eye gets dry, you cry as it tries to moisten itself. That's why you start crying when you don't blink for some time.
i thought it would be the clouds... because the water vapor in them becomes more and more abundant as the sun dries the earth (heats the liquid into gas)
http://8wayrun.com/attachments/lnksc2art1-jpg.3845/