How does a summer cloud become a rain cloud?
Every cloud in the sky is sure to be changeable. A fluffy white summer cloud changes its shape from minute to minute. It may be speeding or dawdling, rising or falling. It may change into a glowering thunderhead. When this happens, there are dramatic changes inside the cloud. Most clouds hang a mile to five miles above our heads and we have a grounds eye view of them. From these distances, we can observe many outward changes. But we cannot observe the misty material in detail or the weathery conditions that exist inside even the gentlest clouds. In fact, even expert researchers have puzzled and probed for years to solve some of these cloudy mysteries. And meteorologists still are unsure of some of the details that occur when a fluffy white cumulus cloud changes into a threatening thunderhead. The weathery drama begins with a mass of misty droplets of water. These droplets of suspended liquid foam the basic material in all clouds. They are so small that meteorologists measure their diam
