*This post is mostly me having fun practicing unit conversions for my Chem 1 class. I figured it may have some relevance to wilderness survival. I honestly used to think that each second between lightening and thunder represented 1 mile (1.6 km). This could have easily led to dangerously miscalculations--5 miles (assumed) vs 1 mile (actual distance).* Feel free to correct any mistakes or provide alternatives!
Final Results
1 mile = 5 seconds
1 kilometer = 3 seconds
0.2 miles = 1 second
0.3 kilometers = 1 second
The speed of light is 0.000621 miles/second. That means lightening is visible to distance of 1,610 miles after just one second. I think it is safe to assume that the speed of light has a negligible effect on the final calculation. We will assume that the time from the actual strike to the time it is visible to you is 0.
1 second ÷ 0.000621 miles/second = 1,610 miles
(www.weather.gov)'s speed of sound calculator says that at 40 degrees F, sound travels at 746.95 miles/hour. For miles/minute divide by 60. And for miles/second divide that by 60 again. This tells us a storm is 0.207 miles away for every 1 second of time between lighting and the sound of thunder. This means that for every 4.83 seconds counted, 1 mile of distance lies between you and the source of the strike.
746.95 miles/hour ÷ 60 minute/hour ÷ 60 seconds/minute = 0.207 miles/second
1 mile ÷ 0.207 miles/second = 4.83 second
Sources:
Speed of Light
Speed of Sound
