Track A Thunderstorm
After you see a flash of lightning, use a stopwatch or count the number of seconds until you hear the thunder.
For every five seconds the storm is one mile away. So all you have to do is divide the number of seconds you count by five to get the number of miles away the storm is.
Light travels faster than sound. The lightning and thunder happen at the same time, but light reaches your eye instantly, while sound takes a little longer. Have you ever seen lightning without thunder? You may have heard people call that ‘heat lightning’. Well actually there is no such thing as ‘heat lightning’. It’s just lightning that is over 15 miles away and too far away for you to hear the thunder.