A rainbow is a multicolored arc in the sky which appears rainbow bread sunlight hits water droplets. How does it get its colors?

And what is at the end of the rainbow? The Sun must be above the horizon and not be obscured by clouds, mountains, or other obstacles. The Sun has to be quite low in the sky. The air opposite the Sun, as seen from your position, must be filled with a large number of water droplets. Rainbows always appear in the sky opposite to the Sun. So, if you have your back to the Sun, the rainbow will arch across the sky in front of you. A rainbow is an optical phenomenon which involves three processes: reflection, dispersion, and refraction.

When a ray of sunlight strikes one of these tiny spheres of water, most of the light bounces off its rear wall and is reflected back. During a rain shower, the air is full of water droplets acting together like a reflective curtain made of millions of minuscule mirrors casting the sunlight back at you. Reflection, dispersion, and refraction inside a water droplet. But sunlight is white—so, if the water droplets reflect the sunlight, how does the rainbow gets its colors? This is where the second process comes into play: dispersion of light.

Pure sunlight may appear white to us, but it consists of all visible colors. As soon as a ray of sunlight enters a water droplet, it is split up into its components, causing its colors to fan out and become visible as a spectrum of colors. This happens both when the ray enters the droplet and when it leaves the droplet again. Each color is refracted in a marginally different direction, creating the impression of a fan of colors. For example, in relation to the direction of the incoming ray of light, the red light component leaves the droplet at a slightly larger angle than the orange component. However, because it reflects and refracts each color at a slightly different angle, only one color from each droplet reaches your eyes. For example, you can only see the red light from droplets that are higher in the sky, and only the orange light from the droplets that are a little lower.

This is how the top two stripes of the rainbow—red and orange—form. Further below, the droplets form an even sharper angle between you and the Sun, so they throw the yellow, green, blue, indigo, and violet components of the sunlight back at you, creating the remaining stripes of the rainbow. This imaginary first, middle, and last name is an acronym made up of the initial letter of each color, in the order they appear in a rainbow. From top to bottom, they are: red, orange, yellow, green, blue, indigo, and violet. Technically, a rainbow is the upper half of a circle of light, which centers on the antisolar point, the point directly opposite the Sun, as seen from your perspective. The lower half of the circle, however, is usually not visible since the water droplets hit the ground before it can form.