We all know what they are. Lightning is static electricity that comes out of clouds. Somehow... yeah, I didn't pay attention that day in science class. Thunder is the sound that thunder makes. They are apparently two different things. But... well, no, they're really the same thing... So why do we have a separate name for the thing and the sound the thing makes?
The only thing I can figure is because lightning and thunder aren't seen and heard at the same time, unless you're VERY CLOSE, because light travels faster than sound. However, it made me wonder if there's anything else that's like lightning and thunder in our language. Do we have separate names for the sight and the sound of anything else? I haven't been able to think of any...