The Story of the Rainbows

"Somewhere, over the rainbow, skies are blue and the dreams that you dare to, dreams really do come true..." The seven colors of the rainbow out of which the human eye can perceive over 700 nuances, have as correspondents the seven musical notes, the seven heavens, the seven planets, the seven days of the week, etc. The symbolic significance of the colors contains universal-human elements, but also differentiating traits and religious-cultural meanings. Generally, it is considered as a good sign to see the rainbow stretch across the sky. It is a message from God, a message of peace, hope and love for mankind. The colors' symbolizing power comprises a very large spectrum, because colors can be associated in different parts of the world, with primordial elements and with space-temporal dimensions.

The rainbow undoubtedly is the most beautiful phenomenon in the atmosphere, which has impressed mankind since forever, being considered as a divine sign which breeds wellness, peace and prosperity. The rainbow is an optical phenomenon born because of the solar light's dispersion and reflection into the raindrops in the atmosphere. It becomes visible when the sun shines from our back to the curtain of clouds from our front, the light reflecting on the serene sky. Clouds are more or less contoured groups of water drops or ice crystal, which are in the state of suspension in the atmosphere, and which come out of the condensation or sublimation of water vapors.

It can be shown through an experiment how light passing through a water drop can go through such phenomena as dispersion and reflection. Let's take for instance a red fascicle. If this light fascicule falls on round water drop, then a part of that red light will come out of the drop in several directions.

When the light fascicule enters the drop, the rays are refracted. Part of the fascicule is reflected by the opposing hemisphere, and the other part comes out of the drop. The reflected part crosses again the drop and then comes out of the drop like the previous fascicule. It is this concentration of light towards a certain direction that makes the rainbow possible. It is only one ray, the one passing through the middle of the drop, that is not being deviated.

We can take a black and white photo of a rainbow. Even though there are no colors in that particular picture, there certainly is a rainbow. In order to explain the existence of the rainbow, one analyzes colors. But colors are not the main issue here. The main question remains, why is there such a thing as a shiny arch in the sky? The sun beams which encounter a water drop spread in several directions. But, because of reflection and refraction, more beams are deviated under certain angles than under other angles. This little preference gives the explanation for the rainbow appearance.

All the sunlight entering the drop is thrown back into a cone. The center of this cone is opposed to the sun. The cone forms a shiny light disk, exactly opposite to the sun. From the ground level, one can only see a part of this disk. But from an airplane, flying high in the sky, one can sometimes see the entire disk. The shiny edge of this disk forms the rainbow.The colors of the rainbow appear due to the phenomenon of refraction. Refraction easily depends on color: different colors of the light cross the water drops at different speeds and refract in a different manner. Because of that, a separation of colors is produced.

Because most people's attention is captured by colors, they cannot notice the portion of shiny disk; they can only see the colorful margin of the disk, which is in fact the rainbow itself.

Like in the optical prism, in the water drops in the clouds light is decomposed in the seven colors: red, orange, yellow, green, blue, indigo and purple. There usually appears a main rainbow and a secondary rainbow. In the arch of the main rainbow, red is on the external part, whereas in the case of the secondary rainbow, red is in the inner part. The colors of the rainbow are all the more vivid and pure as the light reflects and refracts on the bigger raindrops. The moon can also produce rainbows, but they are paler and more difficult to see with a bare eye.