Exactly how accurate is the process of counting the number of seconds from the time you see a bolt of lightning to the time when you hear the thunder? Is that method even slightly scientifically accurate or it is just an old wive’s tale? If it is not very accurate, are there any simple steps to make it so? Thanks.
It is reasonably accurate, provided you can match up the thunder with the bolt that caused it.
FTR, the rule is to count the seconds between the lightning and the thunder, five seconds per mile. That comes out to 1056 ft/sec for the speed of sound. The actual speed of sound is 1088 ft/sec at sea level and 0 degrees Celsius.
How accurate do you need it to be? Go here http://www.measure.demon.co.uk/Acoustics_Software/speed.html to find a speed of sound calculator for various temperatures and releative humidities.
I think the rule of thumb is that the lightning strike is five miles away for every second between the flash and the sound. This is based on hard science regarding light, sound, particles, etc. so it’s not an old wives tale.
Dr. Lao is right, bnorton has his units inverted. It’s five seconds per mile, not five miles per second. Five miles per second is about 8 km/second, and from bnorton’s own link the speed of sound is about 0.33 km/second.
WOW! It’s closer than I’d thunk!