Assume that sound travels at 333 m/s. The sound will travel one kilometre in three seconds.
From: [email protected] [mailto:[email protected]] On Behalf Of John M. Steele Sent: 26 June 2013 12:45 To: U.S. Metric Association Subject: [USMA:52990] Flash To Bang (Lightning Distance) Interesting article on estimating the distance to a thunderstorm: http://www.livescience.com/37734-how-far-away-is-lightning-distance.html She starts with the usual 5 seconds per mile, but she does include a metric version. I'm not sure I want to multiply by 340 m/s in my head, however. It might be easier to just divide by 3 for an approximate (and slightly conservative) distance in kilometers. She mentions, but perhaps doesn't adequately explain, the variation of the speed of sound with temperature. That may be why she gives two values, only one sentence apart. The lower figure is correct at 0 °C, the higher figure near 20 °C (remember it is cooler aloft, so the sound is arriving via multiple paths with differing, generally unknown, temperature profiles).
