22 Nov

A rainbow is a natural phenomena, by which the humankind is fascinated from the very beginning. Scientifically it is caused by refraction of the light in dispersed water particles in the atmosphere. The so-called white light coming from sun is actually a mixture of rays with different frequences (lengths), what means some need slightly more and other slightly less time to pass different media like air or water. In practice we see this as a bent curve made of lines with differen colors.

Appropriate mixture of water and air of course occurs when it's raining and if we have a part of the sky with sun, the necessary conditions for a rainbow are available. Some believe the name rainbow comes from rain (it can be most often seen right after the rain) and bow (rainbow's arc has the same shape as the bow for shooting arrows). There are only seven colors in a rainbow and they are always positioned in the same order (from up/longest radius to down/shortest radius) with their wavelengths:

  • Red (650 nm)
  • Orange (590 nm)
  • Yellow (570 nm)
  • Green (510 nm)
  • Blue (475 nm)
  • Indigo (445 nm)
  • Violet (400 nm)

First man who explained how a rainbo is formed was Isaac Newton after publishing the results of a series of experiments in 1672. He refracted white light with a prism what resulted in a bundle of colored rays with the same order as in a rainbow. To prooe the prism was not coloring the light (coming through his window), he refracted the light together - making white again.

Before that the rainbows sparked imagination of ordinary people for millenniums and many superstitions were formed:


Rainbow related beliefs and superstitions

* Early Christian saw a rainbow as a promise coming from God to not destroy a world by a flood.

* In some religions rainbows represent bridges to heaven or other (higher, more spiritual) worlds.

* In Hindu religion a rainbow is actually an arch used by Indra to shoot arrows of lightning.

* All Aboriginal tribes share stories about a gigantic Rainbow Snake who created the world and all living beings. Being visible after the rain which brings water, a necessity for life in mostly dry land, it definitely carries a logical explanation.

* In some cultures a rainbow, mostly understood as a good omen, can help you make a wish come true and there's a similar belief about a pot of gold being hidden at the end of the rainbow.

* Here is an old song helping you at that:

Rainbow, rainbow,

in your colors of different hue,

my wish is (say it),

dear rainbow, let it come true.

* If the colors of the rainbow reflec on your clothes, you'll be rich as a royalty.

* An interesting superstition is also a belief of ability to change one's gender if a person walks under the rainbow (a reflection might have the same effect). Or jump over it! For some time kids in today's Germany and France were expected to run into a hous as soon the rainbow became visible just to prevent this change. When we think about that it's clear why LGBT community choosed a rainbow for their symbol - they are not afraid of changing gender roles and breaking sterotypes.

* Bohemians, on the other way, believed everybody who gets wet with a rain which passed through a rainbow, was cursed.

* An old English custom of securing one's good luck when seeing a rainbow is making a cross from two sticks on the ground and spitting on all the four corners.

* Old Greeks believed a rainbow placed over a cemetary predicts a start of epidemy.

* If you point at a rainbow, it will bring you bad luck.

* Very intense colors of the rainbow suppose to forcast very hot summer and a rainbow in the winter suggests there will be no more snow until next winter. By the way, a rainbow in cold weather is very rare, because water drops freeze into snow flakes what makes a formation of the rainbow impossible.

*Wood which was touched by a rainbow was considered as sacred among Egyptians and used for sacrifices.


Did you know?

  • Each drop of rain reflects light rays and makes its own rainbow, but we need millions of them to see a rainbow (actually made of millions mini-rainbows).
  • Every human see different rainbow, because he or she stand in different position what means seeing different rain drops at different angles, meaning completely different, altaugh often very similar rainbows.
  • Sometimes a light is reflected twice in the same raindrop, what can cause so-called double rainbow. In that case one of the rainbows (called secondary rainbow) have mirroring order of colors with violet on the top.
  • An arch of the rainbow always always starts at an angle of 42 degrees. When the sun is higher in the sky, a rainbow is positioned lower and vice versa.
  • From the ground we can only see semi circle of the rainbow, but from high positions (for instance from an airplane) we can see full circle.
  • There are also moonbows, also called lunar rainbows, caused by moonlight (sunlight reflected from the moon), but they re rare because this kind of light is very weak.


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