How are rainbows formed??

It's rainy season, you are outside for a stroll and just as you gaze upwards towards the sky you see a beautiful scene. A beam of seven different colors namely red, orange, yellow, green, blue, indigo, violet forming a semi-circle. Yes, you see a rainbow!! Do you know though why that happens or how that happens? Let's read further to know more. 

Let me add another twist to this question, so you don't actually need rains for a rainbow. How about that!! Seems like the curiosity has levelled up. Let's get to the understanding part.

So, a white light or let's say in this case sunlight is made up of different colors inclusive of the colors forming the rainbow. In simple words, scattering of sunlight because of water droplets can be loosely said to be the reason why we see a rainbow.

Now onto more detailing, when sunlight meets the water droplets, there occurs a process called as refraction, total internal reflection which results in the colors in the sunlight being visible to the naked eye thus forming the rainbow.

The behavior is similar to what happens when say a white light is flashed at a prism and we can see a spectrum of different colors being seen from the other end of the prism.

Different droplets emit different color based on when the light hits them, the angle at which it hits. Generally, it is said to be observed that the red light comes higher in the atmosphere than the violet because of red having a higher wavelength and violet having the lowest within our visible range. Lights scattered from the droplets come together to form a rainbow. 

Also, there are certain pre-requisites if one has to see the rainbow,

• The observer needs the sun at the back.
• The lower the sun in the sky, the wider would be the arc of the sun.
• And of course, presence of rain, fog or even fountain works if you can fulfill the first two conditions.

To add a little more of learnings, we need to understand that the light does not just consists of these seven colors, there are more than that. It's just that our human eyes are able to perceive only these seven colors. Also, for that matter our eyes cannot perceive INDIGO color properly hence we see a very blur amalgamation of the color.

Our presence on the ground is the reason why we see only the half arc of the rainbow. A full arc can be visible if one is able to come across the rainbow when airborne say on an airplane.

Why does this phenomenon require water droplets to be around you ask?? I mean why doesn't that happen with air molecules around. Well water droplets are denser in medium than air. It's like how smoothly you can travel when in a crowded passage and in a less crowded one.

You may also want to check out below article.

Why sunrise is blue and sunsets are red.

Now something more to the curious mind?? why the clouds during rainy seasons are dark in color??

Until next time..  Let the curious mind work for the answer..

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