Rainbow is formed when it rains even though sun is shining. The white light of the sun enters the water droplets and and get reflected and refracted. Dispersion of light occurs and the white light of the sun splits into seven colours in the sequence of violet, indigo, blue, green, yellow, orange and red. And so, we can see an colourful arc which we call rainbow. But actually, the rainbow is formed in a circular shape.

Rainbow Formation

A rainbow is a beautiful meteorological phenomenon that occurs when sunlight interacts with water droplets in the atmosphere. The process involves reflection, refraction, and dispersion of light, resulting in the formation of a circular arc of colors. Let's delve into the detailed explanation of how a rainbow is formed.

1. Sunlight and Raindrops

The primary requirement for a rainbow to form is sunlight and raindrops. When sunlight passes through the atmosphere, it consists of various colors, which together form white light. This light contains a spectrum of colors, including red, orange, yellow, green, blue, indigo, and violet (ROYGBIV).

2. Reflection and Refraction

When sunlight encounters raindrops in the air, a part of the light gets reflected at the surface of the raindrop, while the remaining light enters the droplet. As the light enters the droplet, it undergoes refraction, which causes the light rays to change direction and bend.

3. Dispersion of Light

Once inside the raindrop, the light undergoes dispersion, which is the separation of white light into its component colors. The different colors of light have different wavelengths, and as a result, they refract at different angles while passing through the raindrop.

4. Total Internal Reflection

After dispersion, the colored light rays undergo total internal reflection within the raindrop. This means that when the light rays reach the inner surface of the raindrop, which acts as a boundary between air and water, they reflect back into the droplet instead of passing through it.

5. Exiting the Raindrop

Once the light rays have undergone total internal reflection, they exit the raindrop and return to the air. As they leave the droplet, they refract again, causing the rays to change direction once more.

6. Formation of the Rainbow

The refracted light rays exit the raindrop at different angles, depending on their respective wavelengths. This leads to the separation of the colors. As the rays leave the raindrop, they form a circular arc in the sky, with red on the outer edge and violet on the inner edge. The rainbow appears as a semicircle due to the ground obstructing the lower half.

Conclusion

In conclusion, a rainbow is formed through the interaction of sunlight with raindrops. Reflection, refraction, and dispersion of light within the raindrops contribute to the separation of colors and the creation of the beautiful arc we observe in the sky. Understanding the science behind a rainbow enhances our appreciation of its natural beauty.