What thunder looks like

by ANDREW LOFHOLMNews 4 San AntonioFacebook{}|{}Twitter | Email

It started with a spark of curiosity for space physicist Dr. Maher Dayeh 10 years ago when he began working with lighting.

"What initiates a lightning strike inside a cloud? This is an unanswered question," said Dr. Dayeh, who's a space physicist for the Southwest Institute of Research in San Antonio. He's still hoping to find that out one day. He says he's taken a step toward figuring out what exactly causes lightning and thunder. He asks, "Instead of just seeing lightning, if we can visualize the acoustic signature that comes from lightning?"

First he needs the lightning to strike where he wants. Next, he needs a way to record the thunder.

Dayah and acoustic engineer Neal Evans used a device 15 sophisticated microphones, to amplify the sound. He says, "We direct this giant ear at the place where we know lightning is going to hit."

So last July in Florida, where thunderstorms are the norm, they positioned the ear under a cloud that had the right electric field, and met the sky halfway, just as it's ready to unleash. "Right before nature does this (lightning strike), we launch a rocket into the sky," he says.

The rocket is attached to a copper wire to attract and trigger the lightning; you can see the copper vaporizing into a green cloud.

That pure sound of the thunder is then transformed into this into sound waves.

He found "the majority of the sound is coming from the lower part of the channel."

This just proves the concept.

"What we know now for sure is thunder is not just one loud boom from a point source. Sound is emitted from the length of the lightning channel."

This opens a door that's otherwise never been explored in understanding one of nature's great unknowns.

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