The origin of…Rainbow

“Try to be a rainbow in someone’s cloud.” Maya Angelou


A rainbow is formed when (sun)light is spread out into the spectrum of colors and diverted to the eye of the observer by water droplets. The light is diverted when entering a water droplet, reflected inside on the back of the droplet and then refracted again when leaving the water droplet. A rainbow shows the whole spectrum of colors, ranging from red on the outer part to violet on the inner side. Newton originally divided the spectrum into five colors: red, yellow, green, blue and violet. He included the colors orange and indigo later on.
A rainbow doesn´t exist at a particular location in the sky, but depends on the observer´s location and the position of the sun. Even though all water droplets refract and reflect the sunlight in the same way, only some reach the observer´s eye. The bow forms a circle at an angle of 40° to 42° (double rainbowshave an angle of 50° to 53°).
A double rainbow is formed in case not all energy of the ray of sunlight is reflected once and a part of the ray is reflected again. As a result of the second reflection, the colors are inverted compare to the first (primary) rainbow (the color red in both rainbows are facing each other).
A rainbow cloud (or fire rainbow, as can be seen in the picture) is an iridescent cloud, from the Greek word Iris, the goddess of the rainbow. If parts of thin clouds have small droplets or crystals and the sun is at an elevation of 58° or higher, this phenomenon can be observed.

Rainbows are found in various mythological stories around the world. In Greco-Roman stories, the rainbow was seen as a path between Heaven and Earth. In Armenia, it is the belt of Tir, a Sun god.
In the Bible we can find an example in Genesis 9: “And God said, “I have set my rainbow in the clouds, and it will be the sign of the covenant between me and the earth. Whenever I bring clouds over the earth and the rainbow appears in the clouds, I will remember my covenant between me and you and all living creatures of every kind. Never again will the waters become a flood to destroy all life. Whenever the rainbow appears in the clouds, I will see it and remember the everlasting covenant between God and all living creatures of every kind on the earth.

And of course there is the story of the pot of gold at the end of the rainbow. This story comes from Ireland where it was believed that fairies put a pot of gold at the end of the rainbow that was then guarded by leprechauns (fairies that are usually depicted a old men).

a curved line of different colors that sometimes appears in the sky when the sun shines through rain (source: Merriam Webster).

The English rainbow comes from Old English renboga; from rain and bow. Rain comes from Old English regn, rain, from Proto-Germanic *regna-, rain, from a presumed Proto Indo European root *reg-, moist/wet, which could be the source of Latin rigare, to wet/moisten. Bow comes from Old English boga, archery bow/arch/rainbow, from Proto-Germanic *bugon, to bend, from the Proto Indo European root *bheug-, to bend.
Old English also had scurboga, shower-bow (source:
Dutch regenboog has the same origins.
Spanish arcoiris comes from the words arco (bow) and iris. Arco comes from Latin arcus, arh, and iris comes from Latin iris, from Antique Greek ἶρις (iris) from the Proto Indo European root *wey-, to twist.
Italian arcobaleno derives from the words arco and baleno (flash), with arco having the same roots as the Spanish arco and baleno coming from the verb balenare, to flash, from balunicare (=bis-lucinare), to (dis)appear suddenly.

Rainbow in other languages:
Dutch: regenboog
Spanish: el arco iris
Italian: l´arcobaleno (m)


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