Lightning and Thunder Math. Calculating the Distance from a Strike.

I have been fascinated by storms all of my life.  The unpredictability of lightning, thunder, winds and rain add to the aspects of apprehension and excitement to see what will happen. I know I'm not alone.  If you ever sit to observe the surrounding animals when a storm is moving in, you'll notice a change in their behavior as well.  Don't get me wrong, storms can be very dangerous, but if you are smart and safe, they are a very wondrous part of nature.

Enough of ranting about storms.  Let's talk lightning and thunder.  Lightning is the electrical discharge that can occur in nature.  It is similar to the static electricity that sometimes will surprise you when you touch a doorknob, only on a much larger and dangerous scale.  Lightning occurs when a buildup of static electricity is in the atmosphere.  When there is a storm, the ability to build up this static is much more evident and a discharge will occur.

Thunder is the soundwave that is created by the lightning heating the surrounding air around the discharge of electricity.  The drastic amount of heat that is created sends waves of vibrations through the air.  Sometimes it's a low rumble, and sometimes it's a sharp crack.

Growing up, I was told you could approximate the distance you are from a lightning strike by counting the amount of seconds it took from the moment you saw the lightning to the moment you hear the thunder.  I've learned over the years that everyone seems to have a different rule as to how many seconds and how far the lightning strike is.  So, let's look at how to calculate this.

When you observe a lightning strike, what you see is the light generated by the electrical discharge.  When you hear the thunder, you are hearing the sound vibration created by that electrical discharge.  The speed of light and the speed of sound are very different.  Because light travels at over 186,000 miles per second and the speed of sound travels at .21 miles per second, we can approximate the distance you are from the lightning strike.

Since light travels so fast, and we're looking for an estimated difference, we're only going to calculate the distance using the speed of sound.  If you observe a lightning strike and start counting, every second you are able to count before you hear the thunder is about .21 miles.  So, if you count to 5, you have about 1 mile between you and the lightning strike.

This is a very simple way of calculating the distance.  If you want to learn more about the math behind this, calculating the speed of light, or calculating the speed of sound, follow the links below.

Speed of Sound Calculator

Light Year Distance Calculator

Lightning Strike Distance Calculator

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