Lightning and sound travel at different speeds. Lightning travels at the speed of light, which is approximately 300,000 kilometers per second (186,000 miles per second). Sound travels much slower, at approximately 343 meters per second (1,125 feet per second). This means that you can hear thunder from a lightning strike long after the lightning itself has occurred.

To determine how far away lightning is from sound, you can use the following steps:

1. Count the seconds between the lightning flash and the thunderclap.

2. Divide the number of seconds by 5 to obtain the distance in miles.

For example, if you count 10 seconds between the lightning flash and the thunderclap, the lightning is approximately 2 miles away (10 seconds / 5 = 2 miles).