Why Does Thunder Always Come After Lightning? episode artwork

EPISODE · Jun 6, 2026 · 4 MIN

Why Does Thunder Always Come After Lightning?

from Why Though? with Dr. Matt Agnew

Lightning and thunder happen at exactly the same time. So why does the flash always arrive before the boom?In this episode of Why Though?, Dr Matt Agnew explains how static electricity builds up inside storm clouds, what lightning actually is, why thunder is the sound of super-heated air exploding outward, and how a simple counting trick lets you measure how far away a storm is using nothing but your eyes, ears, and a few seconds.What you'll learn:Static electricity happens when electrons jump from one surface to another... like the zap from a doorknob after shuffling across carpet in socksInside storm clouds, ice and water particles bump and swap electrons until a massive charge builds upWhen the charge gets big enough, it jumps to the ground as a giant electrical spark... lightningLightning heats the surrounding air hotter than the surface of the Sun, so fast the air explodes outward as a shockwave... and that shockwave is thunderLight reaches your eyes almost instantly, but sound travels about one kilometre every three secondsThat gap between flash and boom is how far the storm is from where you're standingKey Science Ideas:Electron: A tiny particle with a negative electric chargeStatic electricity: Built-up charge that can suddenly discharge... the giant version is lightningElectrical discharge: Charge moving rapidly to balance itself outShockwave: A fast-moving pressure wave made when air expands suddenly... thunder is exactly thisSpeed of light vs speed of sound: Light arrives almost instantly, sound takes about three seconds per kilometreFun Experiment: The Balloon Static Trick Blow up a balloon and rub it on your hair or a dry jumper. Hold it close to your hair and watch the strands lift up toward it. That's static electricity... the same force that builds up inside storm clouds, just in a much safer, much smaller version. No storm required.Flash-to-Bang Storm Distance Trick Next time there's a storm outside, watch for a lightning flash from indoors. Start counting... one, two, three. When you hear the thunder, stop and divide your number by three. That's roughly how many kilometres away the lightning struck. Three seconds is one kilometre, six is two, nine is three. If thunder follows almost immediately, the storm is very close... stay inside and away from windows.Why Though? The show for little scientists who love asking big questions. Follow or subscribe so you never miss an episode.Follow Dr Matt Agnew: Instagram: instagram.com/drmattagnew TikTok: tiktok.com/@drmattagnew YouTube: youtube.com/@whythoughpod Website: drmattagnew.comFind Why Though? podcast across the internet and share with your friends!Instagram: instagram.com/whythoughpodTikTok: tiktok.com/@whythoughpodFacebook: facebook.com/whythoughpod Hosted on Acast. See acast.com/privacy for more information.

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