When a bolt of lightning is discharged, the light travels at the speed of light while the sound travels at the speed of sound.
The speed of light is 186,300 miles per second (2.9979 * 10^8 meters per second, with 1 mile - 1,609 meters).
The speed of sound is 340.29 meters per second (1,116.45 feet per second, or 0.21 miles per second) in a standard atmosphere at sea level
number of miles from a bolt of lightning =
= (number of seconds between flash and sound of thunder) * 0.21
number of seconds for the sound of thunder to reach the listener =
= (number of miles) / 0.21 = 4.76 * (number of miles)
number of kilometers from a bolt of lightning =
= (number of seconds between flash and sound of thunder) * 0.34
number of seconds for the sound of thunder to reach the listener =
= (number of kilometers) / 0.34 = 2.94 * (number of kilometers)
Limitations:
• The distance is only a rough estimate that is compounded by inaccuracies in timing and counting.
• Lightning that is coming towards you could be significantly closer than you think.
• On a mountain the speed of sound may be faster and the distances to a ground strike shorter.
