General Navigation USCG Question #1261 (Set 40)

If you count 20 seconds between seeing lightning and hearing the thunder, how far is the storm away from you?

Official USCG Answer & Rule Citation

Correct Answer: Option B — 4 miles

Sound travels through the atmosphere at approximately 1 mile every 5 seconds. Dividing the measured 20-second interval between the flash of lightning and the sound of thunder by 5 yields a direct distance of 4 miles from the storm.

100% Free & Open Access — No daily limits, paywalls, or gated answers on BrightMariner.