How The Rainbow Formed 

In our childhood days we  all are amazed how wonderful the rainbow looks and are often looks as magical and sonner or later we all think about how the rainbow formed. Do let's understand the formation of rainbow.

Light and bending:

Rainbows start with sunlight. Sunlight looks white but is actually made up of different colors. When light goes through a glass prism, it splits into many colors. The same thing happens with raindrops in nature to make a rainbow.

When a ray of sunlight enters a raindrop it bends (refracts). The light then strikes the back of the

raindrop, where some of the light passes through and some is reflected. As the light exits the

raindrop, it is refracted again. The angle at which the light emerges depends on the wavelength of

light. This path is illustrated in the small box below, where only the bending of two wavelengths (blue

and red) are shown.

Water Droplets Help

To see a rainbow, there needs to be water droplets in the air, like after it rains. These droplets act like tiny prisms. Here's what happens:

1. Bending Light: When sunlight enters a water droplet, it slows down and bends. This bending splits the light into different colors.

2. Reflecting Light: Inside the droplet, the light bounces off the back of the droplet.

3. Bending Again: When the light leaves the droplet, it bends again. This makes the colors spread out even more.

Colors of a Rainbow

These bending and bouncing actions spread out the sunlight into a circle of colors. The colors in a rainbow are red, orange, yellow, green, blue, indigo, and violet. You can remember them with the word ROYGBIV.

Consider now the diagram below which explains why the colors of a rainbow form an arc. The

angle between the incoming rays of sunlight (white) and all of the red lines, forming a circular cone,

have the same angle. As a result, the light that reaches your eye along these lines have the same

wavelength (color). The same is true for each band of the rainbow.

Right Position To See A Rainbow 

To see a rainbow, stand with your back to the sun and look towards the rain. The light bends at about 42 degrees to make a rainbow. This is why rainbows are often seen in the early morning or late afternoon.

Consider now the diagram below. The sun is behind you (white rays) and there is rain in front of

you (black dots). As the sunlight enters each raindrop, the light is refracted and reflected as described

above. Because the sun is so far away, the rays of sunlight are nearly parallel to one another. As a

result, the angle between the red line and each ray of sunlight striking a raindrop on that line will be

the same. So, the light that reaches your eye along this ray will be of the same wavelength (color).

The same is true for the yellow, blue and intermediate lines corresponding to each color of the rainbow.

Double Rainbow 

Sometimes we can see a second rainbow, fainter rainbow outside the main one

Double rainbows are formed when sunlight is reflected twice within a raindrop with the violet light that reaches the observers eye coming from the higher raindrops and the red light from lower raindrops.