ELi5: Why does the time between lightning striking and when you hear the thunder correlate to how far the lightning landed?

Question

ELi5: Why does the time between lightning striking and when you hear the thunder correlate to how far the lightning landed?

In: Physics

Answer 1

Sound travels slower than light, by a huge amount. Sound needs about five seconds to travel a mile. Light only needs 0.000005 seconds to travel that same mile. So the light from the lightning gets to you right away, but the sound won’t get to you for five seconds, if the lightning struck a mile away. Count the seconds from the flash to the bang and for every five seconds, the lightning was a mile away.