Rainbows are also one of the most beautiful and amazing natural phenomena in our atmosphere. It normally occurs as a brilliant spectrum of light in the sky in shape of an arc and sometimes seen immediately after rainfall.The formation of rainbows is thus manned by complex geometry and optics relating to the reflection, refraction and dispersion of sunlight between air and water droplet. You definitely have to study a lot of things relating to general relativity, waves and optical physics in other to fully understand the formation of rainbows, that is why this post is not about the formation of rainbows but on wonderful fact you should know about rainbows.
What are rainbows?
1. Rainbows are one among many other amazing natural sight in our earth's sky, including auroras, steves and the glory phenomena.
2. Rainbows are produced when sunlight passes through droplets of water, thats why it normally occurs immediately after rainfall. So both sunlight and droplets of water should strike each other at the right time and an observer must be position at the right geometric angle to see it. That is to say that an observer cannot see a rainbow at any angle. He/she must be stationed behind the sunlight, while the rainbow appears opposite the sunlight.
3. We have up to 12 types of rainbows which have their different methods of formation. These includes: Twinned rainbow, multiple rainbow, full-cycle rainbow, monochrome rainbow, fogbow, supernumerary rainbow, rainbow under moonlight, reflected/reflection rainbow, high order rainbows.
4. Have you ever thought of being in the exact location where a rainbow is produced so as to touch it or have a closer sight? The fact is that a rainbow is not like an object or a thing that exist physically, it's a mere optical illusion that is caused by a geometric connection between sunlight and water droplets and an observer just appears to be in the right place and positioned at the right angle to see it. Thus one cannot physically approach a rainbow. Even if you seem to see it physically close to a house or a tree, another observer standing at that location will also seem to see it farther away from itself at the same distance and angle as you saw it.
5. The shape of a rainbow is actually a full cycle not an arc (as it sometimes appears to people), but when viewing from the ground level, an observer only happen to see half of the rainbow which is formed due to the water droplets illuminated above the ground level. But even so, it possible to see a complete circle of a rainbow when viewing from an airplane which is above the ground level.
6. The colour spectrum appearing in a rainbow comes as a result of the separation of sunlight into it component wavelength. This is similar to the spectrum obtained when pointing a light source to a glass prism, we will notice that the light will separate into it component wavelength on the other side. In the case of rainbows, water droplets serves as earth's prism, separating the light waves coming from the sun into it component wavelength.
7. A rainbow has 7 colours, and these colours include Red, Orange,yellow, green, blue, indigo, violet.
8. Isaac newton was the first scientist that distinguish the visible colours present in a spectrum. He divided them into 7 colours which were exactly the number of colours visible to humans on a rainbow. That is to say that although the number of colours appearing on a rainbow seems to be 7, there are also much more invisible colours present in a light spectrum, but who cares, as Robert noted, color is simply a perception created by the human visual system, and as such it has no real physical meaning whatsoever.
9. In some cases, while watching a rainbow one can see another fainter form of rainbow appearing above the original one. This is called a secondary rainbow and this occur due to a double reflection inside of the water droplet. Due to angle factor, the colour order of a secondary rainbow is always in reverse with respect to the original rainbow.
10. An artificial rainbow can be made using a water sprinkler, you must be standing behind the sun while sprinkling the water high above the ground and in a very clear sky.
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