To tell how far away lightning is, you use the time difference between seeing the lightning flash and hearing the thunder. This is called the "flash-to- bang" method:
- As soon as you see the lightning flash, start counting the seconds until you hear the thunder.
- Since light travels almost instantly to you but sound travels much slower, the number of seconds you count corresponds to how far away the lightning strike occurred.
- To estimate the distance in miles, divide the number of seconds by 5. For example, if you count 10 seconds, the lightning is about 2 miles away.
- To estimate the distance in kilometers, divide the number of seconds by 3. For example, if you count 15 seconds, the lightning is about 5 kilometers away
This works because sound travels roughly 1 mile every 5 seconds (or 1 kilometer every 3 seconds) depending on air temperature and conditions, while light travels almost instantaneously
. Safety note: If you hear thunder within 30 seconds of seeing lightning, the storm is close enough to be dangerous and you should seek shelter immediately
. In summary:
Counted Seconds Between Lightning and Thunder| Approximate Distance to
Lightning
---|---
Divide by 5| Distance in miles
Divide by 3| Distance in kilometers
This simple timing method provides a quick and effective way to gauge how far away a thunderstorm is
