To know how far lightning is from you, count the number of seconds between when you see the lightning flash and when you hear the thunder. Sound travels slower than light, roughly 1 mile in about 5 seconds or 1 kilometer in about 3 seconds. You can estimate the distance this way:
- Distance in miles = seconds counted ÷ 5
- Distance in kilometers = seconds counted ÷ 3
For example, if you count 15 seconds between the flash and the thunder, the lightning is about 3 miles or 5 kilometers away. This method is called the "flash-to-bang" technique and gives a simple and effective way to estimate how far the lightning is from you. Lightning is seen almost instantly, but sound takes time to travel, so timing between flash and thunder reveals the storm distance.
