Can you tell how far away a storm is by timing thunder?

Dateline article| David Murphy|

Yes. As a general rule of thumb, thunder travels about 2 miles every 9.5 seconds. That's roughly 1 mile every 5 seconds. If you can count slowly to five between the time of a lightning flash and the time you hear thunder, the lightning bolt probably struck about a mile away. Similarly, if you begin counting at the same pace after each lightning flash in a storm, you can tell whether a storm is getting closer or moving away, based on whether the time between the flash and the thunder clap is becoming shorter or longer.

---David Murphy

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