The Science Behind Rainbows

There it was, arching over the sky in front of me, a gash of color through a gray, rainy afternoon. I had been walking home from a job I hated, depressed about my prospects for the future, and the rainbow was exactly the mood lifter I needed. I think it’s technically impossible to be sad before such spontaneous color and beauty. There’s no wonder that the rainbow has been a symbol for a number of revolutionary movements in history, from the German Peasant’s War in the 16th century to the establishment of the LGBT community in the 1970s. It’s a sign of hope for a new day.

Every culture seems to have its own myth about how rainbows are formed. The ancient Greeks considered them paths between Earth and Heaven made by the messenger goddess, Iris. The Chinese, Hindus, and Celts all had their own lore about rainbows as well. The phenomena are mentioned in the Judeo-Christian Bible and the Epic of Gilgamesh. But what is the scientific explanation for them?

Despite rainbows’ miraculous appearance, the science behind them is actually basic optics, the principles of which were discovered by Isaac Newton in the 17th century and developed by Thomas Young in the early 19th century.

The Bending of Light

Rainbows are formed whenever sunlight shining from behind an observer on the ground is refracted through water droplets in the air. Refraction is considered the “bending” of light, but can be more accurately described as the process of light changing speed as it moves through different densities.

Imagine that you’re swimming through a pool of water. Now imagine that water turning into mineral oil. You’ll be swimming slower, since the thickness of the oil will be more difficult to move through. And when that mineral oil turns to strawberry Jell-O, you’ll be moving even slower.

Light does exactly the same thing as it moves through various mediums. It must change its frequency, or speed, depending on whether it is traveling through air, water, or glass. Different colors have different frequencies, which is why a beam of white light separates into its component colors as it moves through a prism. In the sky, water droplets after a rainfall act as a prism for sunlight, breaking it into the component colors of red, orange, yellow, green, blue, indigo, and violet.

There are as many mnemonic devices to remember the order of these colors as there are people who love rainbows. You may have learned one of the following in elementary school: ROY G. BIV, Richard of York Gave Battle in Vain, or (my favorite) Rainbows Over Your Grass Bring Instant Victory.

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Read more: Environment, Fun, Life, Nature, Nature & Wildlife, Spirit, rainbows

By Molly Mann, DivineCaroline

Disclaimer: The views expressed above are solely those of the author and may not reflect those of
Care2, Inc., its employees or advertisers.

Fred H.

5:50AM PST on Dec 14, 2012

Thank you Samantha, for Sharing this!

December 14
send a green star

Stella G.

9:32PM PST on Nov 20, 2012

Simply magical...

November 20
send a green star

Franco D.

7:46PM PST on Nov 19, 2012

thanks....

November 19
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Syera N.

1:49AM PST on Nov 19, 2012

Every time I see rainbow in the sky, I'm so excited and enjoy that rare moment. Rainbow is breathtakingly beautiful.

Jeannette G.

6:07AM PST on Nov 15, 2012

Beautifully written and explained - thanks!

November 15
send a green star

Theodore S.

5:57PM PST on Nov 14, 2012

I once saw a double rainbow that intersected each other to form an "M" pattern. That's the real golden arches.

November 14
send a green star

Elsie H.

6:21AM PST on Nov 12, 2012

One of the many beauties and wonders of mother nature.

November 12
send a green star

Summerannie M.

1:00AM PST on Nov 12, 2012

Rainbows are awesome like the magically awesome one I wished for and while driving, i sensed I should look out the car window and across the blackest ever sky i have ever seen in my life was this perfectly striped rainbow, Not muted, not hazy, but complete stripes that stood out on their own showing each colour as though it was like a liquorice allsort. Amazing. never have seen one since and maybe no one has seen what I saw. Truly breathtakingly beautiful

Shelly P.

8:33PM PST on Nov 11, 2012

Lynda!!! I am a past Worthy Advisor for the International Order of the Rainbow for Girls,... I hold a "Grand Cross of Colors" for outstanding Community Service, the highest honor We can receive during our service..I was also DeMolay Sweetheart..I was qualifiyed to be Jobs Daughter, ( grand Father, retired 33 degree Mason),, but chose Rainbow, because of what our Order was accomplishing in our community for Charity!!...The Faith, Hope, Charity and Wisdom of putting ALL of Humanity and the Earth first.....why humans really exist..we were taught and accept the responsability of being "Stewards of the Earth and Humanity!!!"..so We pray, act, vote, petition, give thanks..and do it again the next day!!!!..for all of Life on Planet Earth!!...that is why Rainbows are so important to us!!