A common rule of thumb for estimating the distance from one’s location to a lightning strike is to count the number of seconds after seeing the lightning until the thunder (sound) is heard. The number of seconds that have elapsed is then multiplied by 100

Yes, this method is \approx imately correct. When lightning occurs, the electrical discharge heats up the air around it to a temperature of around 30,000 Kelvin. This sudden heating causes the air to expand rapidly, creating a shock wave that we hear as thunder. The speed of sound in air is \approx imately 1,125 feet per second at sea level and at a temperature of 68°F. By counting the number of seconds between the lightning and the thunder, we can estimate how far away the lightning struck based on the time it takes for the sound to travel to our ears. For example, if we count 5 seconds between the lightning and the thunder, this means that the sound wave has traveled \approx imately 5 x 1,125 = 5,625 feet. However, it should be noted that this method only provides an \approx imation, as factors such as temperature, humidity, and wind can affect the speed of sound. Additionally, this method assumes that the lightning is directly overhead, which may not always be the case.