A photo of a dazzling fire rainbow above Pinnacles National Park in Central California this week that was taken by a jogger and sent to the National Weather Service. M. Jimenez/ Bay Area National Weather Service
Photo: M. Jimenez/ Bay Area National Weather Service
Photo: M. Jimenez/ Bay Area National Weather Service

Rare ‘fire rainbow’ puts on colorful show in sky over California national park

A rare weather event known as a fire rainbow was spotted in the sky this week over Pinnacles National Park in central California just east of the Salinas Valley.

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The colorful phenomenon, called a circumhorizontal arc, is caused when light passes through high-altitude cirrus clouds, refracting off the ice crystals in the clouds, according to National Geographic.

National Weather Service meteorologist Roger Gass told SFGate that’s when “you get pretty colors.”

"It's an optical illusion,” Gass said, and only happens when the sun is very high in the sky.

A runner spotted the surreal sight and sent photos of  the National Weather Service.

>> Related: Northern lights mesmerize tourist drivers in Iceland

Fire rainbows are similar to another weather event known as iridescent clouds or rainbow clouds that are sometimes visible after thunderstorms above cumulus clouds.

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