when i see lightning and count, one one thousand, i thought the storm was that many miles away.?

Because sound travels slower than the speed of light, we see lightning before hearing the crack of thunder. The speed at which sound travels is roughly 1 mile every 5 seconds. Therefore, if 15 seconds pass between the flash of lighting and crack of thunder, you can assume that lightning strike occured 3 miles away.

What is even more interesting to know is that successive lightning strikes usually occur 2-3 miles apart. If you feel safe having 15 seconds pass between the lightning and sound of thunder, think again. The next one could be right near you.

Light is faster than sound. So count the seconds from lightning and divide by 5.

For example 10 seconds time means the storm is 2 miles away.

You should be counting 5 seconds for a mile