The Water of Life, by the Brothers Grimm, first published in 1812.
This is such a good story, but it doesn't often make it into Grimms Fairy Tale collections. Maybe because of its length? Anyway, this story has everything: action, suspense, deceit, peril, gold, and a beautiful princess.
Down Comes the Rain, by Franklyn Branley, illustrated by James Hale, Harper Collins, originally published in 1963.
This is a very good book for learning about the water cycle. I do wish the author had used all three terms of the water cycle, though. "Precipitation" is conspicuously absent. This book also contains a very good description of how hail is formed.