ExplainerTools

Short · Weather and sound

How far away was that lightning?

Light arrives almost instantly; thunder crawls at about 340 m/s. Count the seconds between them: every 3 seconds is about a kilometer, or 5 seconds a mile.

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Opens Thunder Timer. Change the same thing yourself.

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Transcript

How far away was that lightning? The flash and the thunder happen at the same moment. But light reaches you almost instantly, while sound crawls at about three hundred forty meters a second. Count the seconds between them. Now drag the strike closer. Every three seconds is about one kilometer, or five seconds a mile. Ten seconds? Nearly three and a half kilometers. And if you can hear thunder at all, you're likely within striking distance. Try it yourself at Explainer Tools dot com.