The Science Behind: Rainbows (part 2)

Cover page- Sara Chaudhari


Violet, Indigo, Blue, Green, Yellow, Orange, and Red.


That's how I memorized the colors of the rainbow. Backward!



Have you ever wondered why those specific colors were in the rainbow? Why not pink, why not gray, why not lavender?


Have you noticed that rainbows also (almost always) appear in the same color order? Red, orange, yellow, green, blue, indigo, and violet.


Usually, those colors are present in the air, but we don't see them, we see all of them mixed which makes white. Sunlight appears white, which means that it's a mixture of all the colors of the rainbow.

When light hits the water, some light is reflected. The electromagnetic spectrum is made of light with different wavelengths, and each is reflected at a different angle. Each color is separated producing a rainbow!



National Geographic states, "Red has the longest wavelength of visible light, about 650 nanometers. It usually appears on the outer part of a rainbow's arch." Naturally, this means that violet has the shortest wavelength, and usually appears at the end.


At the edges, the colors of the rainbow overlap. This mix produces a "white" light making the inner part of the rainbow brighter than the outer.


Rainbows are much larger than just seven colors. Infrared radiation exists beyond the red light we see, ultraviolet goes beyond violet. The human eye is only capable of seeing those seven colors, but there are also radio waves, x-rays, and gamma radiation. Scientists use a spectrometer to study the parts we can't see.


What's better than a rainbow? TWO RAINBOWS!!!



Sometimes light is reflected twice inside a raindrop causing a double rainbow. The spectrum of the double rainbow is the opposite of a normal rainbow due to the double reflection! Red is on the inside and violet is on the outside.


The atmosphere opposing the rainbow is often glowing! This glow occurs because when rain or drizzle is falling between the audience and the sun.


This glow is formed by the light passing through raindrops that are not reflected. Scientists like to like this a 'zero-order glow'



Light can be reflected from many angles. A rainbow's order is its reflective number. Higher-order rainbows appear to viewers as both facing towards and away from the sun.




A tertiary rainbow, for example, appears to be facing the sun. Tertiary rainbows are third-order rainbows - the third reflection of light.


A tertiary rainbow is difficult to see:

1) The viewer is looking at the sun, but the center of a tertiary rainbow is not the antisolar point, it's the sun itself.

2)Tertiary rainbows are much fainter than primary, or secondary rainbows

3) Tertiary rainbows are much broader than primary and secondary rainbows.


Quaternary rainbows a.k.a fourth-order rainbows are even fainter and broader than tertiary rainbows.


Beyond quaternary rainbows, higher-order rainbows are named after their reflected number, and scientists have detected a 200th order-rainbow.



Reflection Rainbows usually appear above a body of water. A primary rainbow is reflected by the water producing a reflection rainbow. Reflection rainbows often stretch above the original primary rainbow.

A fogbow is formed pretty much the same way as a primary rainbow. Light gets refracted and reflected by the fog. A fogbow in the clouds is called a cloud bow.


Fogbows don't have much color, they mostly appear white, with a reddish tint on the outside, and a bluish tint on the inside.



Did you know, there are things called 'moonbows' a.k.a lunar rainbows. They are made from light emitted by the Moon. However, the moon does not have its own light, so it borrows light from the Sun. Since moonbows are made from borrowed light, they are much fainter.



Now you have all this information on rainbows. They're not uncommon, you just need to be at the right angle.


Until next time...


Stay Curious ;)


Love

Sarah



Sources:

https://ssec.si.edu/stemvisions-blog/science-rainbows

https://www.nationalgeographic.org/encyclopedia/rainbow/


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