Today, the weather here is very sunny, but suddenly there is a rainbow. I am curious. Would you please explain it to the professionals?

First of all, we need to understand the meteorological principle of rainbows.

The size of water droplets in the air determines the color and width of the rainbow. The bigger the raindrops, the narrower the rainbow band and the brighter the color. The smaller the raindrops, the wider the rainbow band and the darker the color. When raindrops are small enough, the light splitting and reflection are not obvious, and the rainbow disappears. This shows that the formation of rainbow is directly related to the existence, quantity and size of raindrops in the air, and in turn, rainbow is related to weather changes. For example, the color of the rainbow changes from bright to dark, and the width changes from narrow to wide, indicating that the raindrops in the air change from big to small. It can be speculated that the air may gradually stabilize and the weather conditions will gradually stabilize.

The formation of rainbow is not directly related to rain, but it is the basic condition for rainbow imaging that it is easy to form rainbow after rain.