Why do rainbows appear after rain?

Rainbow is formed by the reflection and refraction of sunlight in the air into water droplets.

When sunlight passes through the prism, the forward direction will be deflected, and the original white light will be decomposed into red, orange, yellow, green, blue, indigo, purple and other bands. When it rains or after rain, the air is full of countless small water droplets that can refract sunlight. When sunlight passes through water droplets, it not only changes the direction of progress, but also becomes a rainbow we see if the angle is right.

The size of water droplets in the air determines the bright colors of rainbows. The bigger the water drop, the brighter the rainbow, and the smaller the water drop, the brighter the rainbow. There are often thunderstorms or showers in summer, and the scope of these rains is not large. It often rains here and often sunrises there. When the sun shines on the small water droplets that stay in the air after the rain, a beautiful rainbow will appear.