The Colors of the Rainbow (ROYGBIV)

We see rainbows because the sun is behind us, reflecting sunlight off the rain, waterfall, mist, dew, or even a water fountain that is before us.

Refracted, they are broken up into the blues, reds, and oranges we know. Double, or secondary, rainbows form when a beam of light is refracted twice.

Contrary to popular belief, the colors of a rainbow are not "pure." The classical rainbow is composed of overlapping bows of individually pure spectral colors. However, when we observe a rainbow, what we see are actually mixtures of colors. Each color in the bow contains longer-wavelength colors mixed in.

For example, the blue color in the rainbow also contains significant amounts of green, and lesser amounts of yellow and red.

What is a Classical Rainbow and it's Composition?

Rainbows in Culture and Symbolism

Throughout history, rainbows have held significant cultural and symbolic meanings. In various mythologies and folklore, rainbows have been seen as bridges between realms, symbols of hope, and representations of divine messages. They have inspired artists, poets, and dreamers across cultures and continue to evoke a sense of wonder and awe.

From the classical depiction to the intricate details of color mixing, rainbows offer us a glimpse into the fascinating world of atmospheric optics. Whether we observe them after a refreshing rain shower or encounter them in our imaginations, rainbows remind us of the beauty and complexity that surround us in nature.

Traditionally, the rainbow's colours are described as red, orange, yellow, green,blue, indigo and violet. In fact, our eyes can discern many more indivual hues.

Rainbow colours are not "pure". The classical rainbow., is made up of overlapping bows of individually pure spectral colours.

The final colours that we see are mixtures. Any one colour of the bow has longer wavelength (towards red) colours mixed in.

Look for instance at the blue; there are significant amounts of green present and lesser amounts of yellow and red.

Yellow is contaminated with reds, green with yellows and reds and so on. Well inside the main bow all these colours mix to form white. Rainbow colours are not pure. Those of the circumzenithal arc ice crystal halo are purer.

It was an amazing day. First black clouds appeared like an apocalypse. After that lightening with rain. Then we has this red rainbow. When the sun is low, blows are high. Sunset rays have a long path through the atmosphere and are highly reddened due to blue light being preferentially scattered away by air molecules and fine dust.

BUT WHY A RED DISK?

All primary rainbows are disks. It's colour contasts with the sky. When the sun is higher the disk is white.

"Do not all charms fly

At the mere touch of cold philosophy?

There was an awful rainbow once in heaven:

We know her woof, her texture; she is given

In the dull catalogue of common things.

Philosophy will clip an Angel's wings,

Conquer all mysteries by rule and line,

Empty the haunted air, and gnomed mine--

Unweave a rainbow.."