Math and Weather Activity For Children – Calculating Lightning Distance

Bad weather does not need to be a frightening time for children. In fact, you can turn a stormy night into a great family activity that can be educational and fun for all members of your household.

The light that is generated from a bolt of lightning arrives at your eyes almost simultaneously. But since light travels faster than sound, you will always see the lightning before you actually hear it. The light arrives almost instantly moving at 186,000 miles/second while sound travels to you at approximately 770 miles per hour. At this rate, it takes sound just about 5 seconds to travel the distance of a mile. Using this information, we can easily calculate how far the lightning is away.

So to begin this activity, on the next stormy night, find a safe area and watch for flashes of lightning. As soon as you see a strike, start counting or use a stopwatch to record the number of seconds between the flash and the thunder that follows.

Once you have determined the seconds between the initial strike and the boom of thunder, all you have to do to estimate the distance is divide the seconds by 5. For example, if you see a bolt of lightning and hear thunder 9 seconds later, you would conclude that the lightning is approximately 1.8 miles away. We found this figure by dividing 9 by 5, which equals 1.8.

Here is another one: How far would a lightning strike be if you hear thunder 21 seconds after the first flash of lightning? Take 21 and divide it by 5 and your answer should be 4.2. So the lighting strike is around 4.2 miles away.

You should be aware that this method is not always 100% accurate. The thunder that you hear might not necessarily correspond directly to the lightning that you see. Instead, it could be from a different bolt of lightning all together. Not all lightning hits the ground, so many lightning strikes are out of your view, although the sound of the thunder will still reach your ears.

Safety should definitely be a top priority when observing lightning. You should stay away from metals, appliances, and tall objects such as trees or light poles.

You do not need to be a professional meteorologist to determine how far lightning is away and have fun observing the weather. All you need is a stopwatch and safe area to watch for lightning to turn an otherwise dreary evening into a fun and education experience.