Rainbows in the clouds: Rare but colorful display spotted around Seattle

Jason Fink

SEATTLE -- We're all familiar with the rainbows that form during the frequently showery days around the Northwest. But what about rainbows on days when there isn't a raindrop to be found?

We got a few people sending in photos of a beautiful colors painted across clouds low on the horizons.

"We were playing a card game outside today and looked up at the sky to see this incredible sight floating by," said Barb DePoppe. "Never in our lives had any of us seen anything like this before."

The displays are known as "circumhorizontal arcs" -- that's the official term. Colloquially they're also sometimes called "fire rainbows" although they have nothing to do with fire, except for their appearance, and, while we're at it, have nothing to do with "rain" either.

Catching a glimpse takes luck and timing -- the colors are formed from the ice crystals in those wispy clouds refracting the sun's light like a prism. But the sun angle needed to create the displays around Seattle's latitude only happens for about the 12 week period surrounding the summer solstice, and even then, the sun is only high enough in the few hours surrounding solar noon (which is ~1 p.m. Pacific Daylight Time)

But Monday, we had the right ingredients in place. We're also a bit lucky in that the farther north you go, the less often you can see these arcs; once you get to about 55 degrees north, you'll never see them. Sorry, Copenhagen, you'll just have to look at the pictures in our photo gallery!