Rare Horizontal Rainbow Forms Over Paris, Goes ViralPhotographer: 'This light phenomenon looked like a rising aurora over Paris'
Photo by Bertrand Kulik / Facebook
How does Paris' already stunning skyline become even more spectacular?
One way, it turns out, is with the addition of a rare, rainbow-like prism forming across the sky.
Bertrand Kulik spotted the usual sight from his apartment earlier this month and grabbed his camera.
"I have never seen a rainbow like that before," the 33-year-old Parisian told The Daily Mail. "This light phenomenon looked like a rising aurora over Paris."
It didn't last long, he said, but his photo, which he posted to Facebook on March 18, has captured peoples' imagination. The image has gone viral, appearing in newspapers and on websites around the world.
Many are calling it a rainbow, but technically, that's not the term for it.
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"It's known as a circumhorizontal arc," said meteorologist and Ask SKYE columnist Renny Vandewege. "It's basically a halo that runs parallel to the horizon. It only forms when the sun is very high in the sky. It occurs when the sun hits ice crystals in the clouds."
Vandewege has spent more time than most studying the sky, but he'd never seen such a long circumhorizontal arc before, at least not in person.
"This one is rare because it's so long," he said. "Usually they're fairly small, like little fragments, broken up because of the clouds. The unique sun angle combined with the length of the cloud is what makes for such a long arc."
The prism includes the same colors as a rainbow, and it forms in a similar way, he says, requiring the refraction of light.
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