The World’s Coolest Rainbow Appeared Over California This Week

“Fire Rainbows” only appear in the US about five times a year.

M. Jimenez

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A flame-like streak of colorful clouds appeared in the sky over Pinnacles National Park in central California on Tuesday. 

A man running in the park spotted the “fire rainbow” and sent pictures to the Bay Area division of the National Weather Service, which tweeted the eye-catching images, along with the technical name for the phenomena.

So what combination of clouds, moisture, and light come together to create these beautiful circumhorizontal arcs? How are they the same, and different, from the usual rainbows we see? 

Basically, ice crystals in wispy, high-altitude cirrus clouds act like thousands of tiny prisms, similar to the role of raindrops in a normal rainbow. For a fire rainbow to appear, those hexagonal crystals need to be lined up perfectly and so does the sun, which must be very high in the sky (at least 58 degrees above the horizon). As sunlight streams through the cloud at the right angle, the crystals refract the light and create an array of colors.

The likelihood of seeing one of the arcs depends on where you live. Latitude is crucial; the further from the equator you are, the less time the sun is sufficiently high enough in the sky. In the US, the arcs may be seen five or more times each summer, according to the website Atmospheric Optics. The site also adamantly clarifies that the colorful arc “is not a rainbow and has nothing to do with fire.”

“There’s no real way of predicting these types of things, the same way we can’t predict rainbows,” says Roger Gass, a meteorologist with the NWS Bay Area office, who has never seen a fire rainbow himself.  “It’s always worth looking up in the sky to see what’s there.”

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DEMOCRACY DOES NOT EXIST...

without free and fair elections, a vigorous free press, and engaged citizens to reclaim power from those who abuse it.

In this election year unlike any other—against a backdrop of a pandemic, an economic crisis, racial reckoning, and so much daily crazy—Mother Jones' journalism is driven by one simple question: Will America will move closer to, or further from, justice and equity in the years to come?

If you're able to, please join us in this mission with a donation today. Our reporting right now is focused on voting rights and election security, corruption, disinformation, racial and gender equity, and the climate crisis. We can’t do it without the support of readers like you, and we need to give it everything we've got between now and November. Thank you.

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