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Comment by nkrisc | Hacker News Reader

I was once walking along a soccer field in Costa Rica during the daily afternoon shower in the rainy season. Suddenly the entire sky beyond the treeline turned completely white. It was like I was looking at a black and white silhouette of the treeline. At the same moment I heard the loudest sound I've ever heard. It was like an explosion; I could feel the ground tremble. I have no idea how close the strike was, only that the sound and lightning were simultaneous from my perspective. It honestly could have been just on the other side of the trees across the field, or maybe half a kilometer away, I couldn't tell you. All I can say for sure is I ran like hell to the nearest house.

I'm not regularly around explosions and such so I've never experienced anything like that before or since.

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This is the one thing that can be use to easily tell apart people who have been truly close to lightning, and those who only think they have.

Lightning is a powerful event and even if you're not that close to it, it can appear overwhelming and make you think you were much closer than you were. People who have experienced this talk a lot about what it looked like.

Everyone I know who has truly been close to a lightning strike unfailingly mention the sound above all else.

You comment reminds me of descriptions from people who have been near large capacitors blowing. Once you have heard/felt it, you don’t forget it.

A transformer blew about 200’ from my house. Woke me in the middle of the night thinking someone had just bombed my car. Enormously loud.

Supposedly that can also just be a giant fuse blowing, to protect the lines/transformer (just happened to watch a video about it on YouTube recently).

I once was driving over an underground transformer when it exploded. A tremendous clap followed by a comparatively long and low hooting sound. Lots of vile smoke.

I was lucky to be in a car. A while back the same thing happened to someone walking over the top of a transformer causing very serious injuries.

I’m always kind of creeped out around iron grilles now.

Had a relatively close strike happen during a thunderstorm, a thunderstorm that was intense enough that we had to stop the car entirely as you couldn't even see the hood of the car through the waterfall like rain.

When the lightning struck the thunder felt instant. It was however clear from the admittedly blinding flash that it was still a ways off. Probably some hundred meters.

But as you said, the sound. In a car, in a torrent of rain, it was the loudest and sharpest sound I believe I have ever heard. By the sound of it I could have sworn it was inside the car as couldn't tell it had been muffled at all by either the torrent of rain, or the bodywork and careful sound dampening in any modern car.

There had been lightning all around us for a while, but we barely heard the thunder of those strikes through the thunderous murmur of the sky falling down on us. The difference was truly astonishing!

Is this "just" the sound of thunder? Or is there some other sound from a lightning strike, if you're very close to it?

Thunder is the sound that lightning makes, no? Unless I’m misunderstanding, the two things you’ve described are one and the same.

That being said, if you’re close—really close—the sound does change. Lightning used to regularly strike a pair of trees just outside my bedroom window when I was growing up, since it was the top of a hill, and the trees were the tallest thing around, by far. Were my window open, I could reach out and touch the taller of the two trees.

The sound is so loud and so abrupt that I’m not really sure how to describe it. It’s instantaneous—over before you realize that there was a sound. It’s not a steady, drawn-out rumble like you might expect. In addition to the overwhelming, deafening crack, sometimes I would hear what sounded like a scream or a whistle—but that was almost certainly just a sensory artifact and not a real noise. Other people in the house would describe different artifacts.

I probably make it sound scary, but I always looked forward to thunderstorms as a kid, and each time I’d hope the storm would get close enough to strike those trees. It was absolutely amazing to watch—and, being a child with no sense of danger, I’d sit right by the window.

I have been in a couple "close" strikes where the thunder was trailing the lightning by, maybe, a tenth of a second or so. Although they were several years apart, in both cases I distinctly heard—or maybe felt—a "pop" at the exact moment of the flash, similar to the sound of a high-power flash unit.

Maybe it was my imagination but it was so distinct that I wonder if it was the sound of discharge from nearby objects, or … something.

Both sound and light originate at the same time. Light travels faster than sound. If you are close to a strike, the time gap between lightening and thunder is smaller.

On a related note, I was in the middle of a major forest fire once. The sound was the most intense thing. Every time a slight breeze started blowing, a deep roar like a freight train filled your chest cavity.

Wow. That's an image.

Well I don't really know what group I fall into because I couldn't tell you how close I was. All I know is it was the loudest noise I've ever heard and I felt the ground shake. Never been in an earthquake so it's the also the only time I've ever felt the ground shake. But 50 meters? 500 meters? No clue.

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