This is really well done. In the last line of the first stanza, I think you meant 'gravity's,' not 'gravities.' But overall, good work.
I remember reading once how many trillions of gallons of water fall to the earth each day as rain. Your poem made me think of that. Also about the time my husband and I were hiking in the Utah desert and ran out of water by early afternoon. It was blazing hot and by the time we made it back to camp I was literally staggering. I could have used some "silver sky of balloons" then.
I had a hike like that in the mountains once-makes you realize what a precious commodity it really is...Zorba-quite right and thanks