By studying different types of clouds on a given day, we can predict the weather. For example, cumulonimbus clouds are powerful, towering thunderstorm clouds. From a distance, these can be beautiful. But beware, they often mean dangerous lightning, hail, or even tornadoes.
Pilots and sailors, who need to keep a close eye on the weather, rely on the atlas. It’s also helpful to hikers—you don’t want to be caught on a mountain when there’s lightning nearby!