Rainbow Variations

_Elsa_

‘Glow - The atmosphere opposite a rainbow, facing the sun, is often glowing. This glow appears when rain or drizzle is falling between the viewer and the sun.  The glow is formed by light passing through raindrops, not reflected by them. Some scientists call this glow a zero-order glow.

Double Rainbow - Sometimes, a viewer may see a "double rainbow." In this phenomenon, a faint, secondary rainbow appears above the primary one. Double rainbows are caused by light being reflected twice inside the raindrop. As a result of this second reflection, the spectrum of the secondary rainbow is reversed: red is on the inner section of the arch, while violet is on the outside. 

Higher-Order Rainbows - Light can be reflected from many angles inside the raindrop. A rainbow's "order" is its reflective number. (Primary rainbows are first-order rainbows, while secondary rainbows are second-order rainbows.) Higher-order rainbows appear to viewers facing both toward and away from the sun. A tertiary rainbow, for example, appears to a viewer facing the sun. Tertiary rainbows are third-order rainbows—the third reflection of light. Their spectrum is the same as the primary rainbow. 

Tertiary rainbows are difficult to see for three main reasons. First, the viewer is looking toward the sun—the center of a tertiary rainbow is not the antisolar point, it's the sun itself. Second, tertiary rainbows are much, much fainter than primary or secondary rainbows. Finally, tertiary rainbows are much, much broader than primary and secondary rainbows.

Quaternary rainbows are fourth-order rainbows, and also appear to viewers facing the sun. They are even fainter and broader than tertiary rainbows. Beyond quaternary rainbows, higher-order rainbows are named by their reflective number, or order. In the lab, scientists have detected a 200th-order rainbow. 

 

Twinned Rainbow - A twinned rainbow is two distinct rainbows produced from a single endpoint. Twinned rainbows are the result of light hitting an air mass with different sizes and shapes of water droplets—usually a raincloud with different sizes and shapes of raindrops. ’ (Source)  

Let’s continue – More rainbow variations

Start at the beginning - Elsa learns all about rainbows