How Rainbows Form: 12 Types of Rainbows

Rainbow Over the Pacific Street Bridge


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Most everyone is fascinating by rainbows and how rainbows are formed. Did you know that there are 12 different kinds of rainbows?

On December 17, 2015, Jean Ricard, a serious rainbow scientist (what a fun job!), reported that there are 12 types of rainbows and why.

A rare winter rainbow SOURCE: Old Farmer’s Almanac

How Are Rainbows Formed?

Rainbows are wonderful reflections of sunlight off raindrops. As the light is reflected, it is refracted, which changes the direction on the light wave. Different wavelengths of light, which we see as colors, bend at different angles.

Since sunlight is made of different colors, we see the white light broken into an array of colors—the rainbow. The more the light bounces around, reflecting and refracting, the more different rainbows there are.

12 Kinds of Rainbows

There are 12 types, including double rainbows, multiple rainbows, reversed rainbows, and even rainbows with colors missing, so that they don’t have any blue or green.

Rainbows are sunbeams reflected by raindrops and the reflections can get crazy. Source: Wikipedia

The big debate is why rainbows are so different. In general, the scientists are divided between the “fatty” camp and the “low-life” camp. Most science has said that the size of the raindrops shape how they reflect light and what the rainbow will look like. Others have said that it depends where the raindrops are—since a low-lying haze of water will reflect at a different angle than a high shower of drops.

What Ricard showed is that while both are important, the most important rainbow fact is the where the drops are—high or low. That’s why you see rainbows change as the drops fall through the sky. They can fade, brighten, split into double or multiple bows, be full circles or low arches.

If rainbows that form are too low, the thickness of the air makes it impossible to see the shorter waves of light—the purples and blues. The most low-lying droplets that are filtered through haze and smog finally filter out all but the long waves of red.

Some rainbows are missing colors or even solid red, a nice Christmas color. Source: Wikipedia

Rainbows become rare in winter; ice scatters lights instead of refracting it. So as you sit through cold winters, dream of the twelve rainbows that sparkle in summer skies.

Learn the best place to look to find a rainbow.

About This Blog

Evelyn Browning Garriss doesn't just blog about the weather forecast; she provides insight on WHY extreme weather is happening--and a heads up on weather to watch out for. A historical climatologist, Evelyn blogs about weather history, interesting facts about the weather, and upcoming climate events that affect your life--from farming to your grocery bill. Every week, we look forward to another great weather column from Evelyn. We encourage our weather watchers to post their comments and questions--and tell us what they think!

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