Have you ever seen lightning without hearing the thunder who accompanies him? This type of silent flash is often called a “lightning flash”. heat inappropriately. What is it really ? This is a flash completely identical to the others, neither more nor less.
A flash seen at a great distance
“Heat flashes” are actually produced by thunderstorms far away… so far away that you can see the lightning which is signaled by brief illuminations streaking the sky but the thunder cannot be heard from where you are because of the distance.
Here’s why: the speed of light (about 300,000 km/s) is extremely fast compared to that of sound (300 m/s). Moreover, the blow of thunder and its wave dissipate more easily by propagating and, when one is too far away, the thunder is no longer heard and becomes inaudible.
If, during a hike, you are surprised by a thunderstorm, remember that the longer the time that separates lightning thunder is short, the closer you are to the lightning strike, the more danger you are in. To calculate the distance between you and lightning, count the number of seconds that separate the sight of lightning from the sound of thunder. The shorter this time, the longer it takes to shelter rapidly !
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[EN VIDÉO] Kézako: where do lightning come from, from the ground or from the sky? Storms are usually accompanied by rain, lightning and thunder, but do you know where exactly lightning originates? Unisciel and the University of Lille 1 explain to us, with the Kézako program, the mysteries of this phenomenon.
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