Explainer: What is thunder and lightning?

Weather News

(WWLP) – This time of year is when we get those garden-variety thunderstorms. But how exactly does lightning form, and what is the sound of thunder? I’ll take you through step by step.

Electrons begin to emerge from the base of the storm toward the ground. This is known as the stepped leader. It usually branches out in many directions as it gets closer to the ground.

As the stepped leader approaches the ground, its negative charge attracts vast amounts of positive charge upward from the ground. This produces what’s called streamers which are electric channels that come up from the ground. As the stepped leader and streamers meet, a powerful electrical current flows, this is known as the return stroke.

This “return stroke” is more than 99% of a lightning bolt’s luminosity and is what we see as lightning. This stroke goes from the ground up to the sky, but it happens so quickly our eyes can’t see it – at about 60,000 miles per second.

If there’s enough charge in the cloud after the first strike, you may see that process happen multiple times, which is what can cause lightning to have that flickering effect.

The sound of thunder that results from a lightning strike is due to the sudden expansion of air surrounding the extreme heat from that lightning strike. We’re talking 50,000 degrees Fahrenheit. That sudden expansion of air creates a sort of a shock wave, and we hear it as a thunderclap.

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