In the flash-to-bang method, the distance to a storm can be estimated by which of the following?

In the flash-to-bang method, the distance to a storm can be estimated by which of the following?

• A. Count the seconds between lightning and thunder and divide by 5 to estimate miles.
• B. Count the seconds and multiply by 2 to estimate miles.
• C. Divide the seconds by 10 to estimate miles.
• D. The distance cannot be estimated from a single flash.

Answer: (A)

The key idea is that light is essentially instantaneous, while sound travels at a finite speed. The speed of sound in air is about 343 meters per second (roughly 1,125 feet per second), which works out to about 1 mile every 5 seconds. So by counting the seconds between seeing lightning and hearing thunder and dividing by 5, you get an approximate distance in miles. For example, a 10-second delay equals about 2 miles away. Variations in temperature can change sound speed slightly, but the 5 seconds per mile rule is a handy and widely used estimate. The delay can be measured from a single lightning pulse, so you can estimate distance from that one event.

The key idea is that light is essentially instantaneous, while sound travels at a finite speed. The speed of sound in air is about 343 meters per second (roughly 1,125 feet per second), which works out to about 1 mile every 5 seconds. So by counting the seconds between seeing lightning and hearing thunder and dividing by 5, you get an approximate distance in miles.

For example, a 10-second delay equals about 2 miles away. Variations in temperature can change sound speed slightly, but the 5 seconds per mile rule is a handy and widely used estimate. The delay can be measured from a single lightning pulse, so you can estimate distance from that one event.