WRAL WeatherCenter Blog

That upside down rainbow you saw this week is called a circumzenithal arc

Posted November 26, 2019 12:08 p.m. EST

Credit: Susan Bagwell

— On Sunday, Susan Bagwell sent WRAL a beautiful image of what appears to be an upside down rainbow.

It appears to be an upside down rainbow, but it's not formed in the same way as a rainbow. It's called a circumzenithal arc and is caused by the refraction of sunlight through ice crystals in the upper atmosphere.

It's similar to a halo around the sun or moon.

To see a circumzenithal arc, the sun has to be at about 22 degrees above the horizon. This happens more often in colder months when the sun's angle is lower and we are more likely to see a mostly clear sky with cirrus clouds.

Bagwell took the photo from her home in Raleigh in the Glenwood Avenue area. She said no adjustments were made.

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