Ask Ellen: How do firebows form?

Ask Ellen

GRAND RAPIDS, Mich. (WOOD) — Sophie from Kalamazoo has an eye for clouds! She has spotted a few “firebows” and wants to know how they form. These splashes of color are showstoppers and can be seen in West Michigan from time to time!

This is a shot of a firebow spotted in West Michigan three years ago. Notice how the colors follow the same order as a normal rainbow.

Even though these rainbow patches are known as “firebows,” the actual scientific name for them is “iridescence.”

These gorgeous pieces of rainbow appear on very high clouds. Most only last for a matter of seconds before disappearing again. “Firebows” need a cloud to form, they will never appear in just wide open sky.

HERE’S HOW THEY FORM:

Not all clouds can make a firebow. Only a few can! Most clouds are composed of water vapor droplets and ice crystals of all shapes and sizes.

For a firebow to form, cloud droplets must be especially small and very uniform in size. As sunlight hits the tiny droplets, it refracts and reflects the light in the exact same way that rainbows form.

Rainbows form when sunshine hits rain showers just right. Firebows happen when sunlight hits cloud droplets just right! This usually means firebows look extra wispy and diffuse compared to rainbows.

Courtesy: John Burleigh

HOW FIREBOWS ARE DIFFERENT THAN SUN DOGS

Firebow splashes are different than sun dogs. Sun dogs also look a little bit like rainbows, but they can only form next to the sun. If you spot a splash of color on one side of the sun, look to see if there is a matching one on the other side of the sun. Sun dogs will always have the red color of the splash closest to the sun. Firebows will usually have the red color on the top of the cloud but not always.

Here is an example of two sun dogs next to the sun sent to us by a viewer.

Sun Dogs besides the Sun courtesy: Elaine Fleming

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