If water is heavier than air, why do clouds stay up in the sky?

serpa

Clouds are composed primarily of small water droplets and, if it's cold enough, ice crystals. The vast majority of clouds you see contain droplets and/or crystals that are too small to have any appreciable fall velocity. So the particles continue to float with the surrounding air. For an analogy closer to the ground, think of tiny dust particles that, when viewed against a shaft of sunlight, appear to float in the air. http://www.scientificamerican.com/article.cfm?id=why-do-clouds-float-when Aug 14 10, 8:32 PM

star_gazer

Clouds are dropping, constantly. Fortunately, clouds drop at a much slower pace than a water balloon. They are downright sluggards: They drop at a measly 0.3 centimeters per second. And cloud drops are so tiny, about 0.01 centimeters in diameter, that their decent is not even noticeable to the human eye. http://en.wikipedia.org/wiki/Cloud Aug 14 10, 8:42 PM