What do you mean that the appearance of rainbow is related to the weather change at that time?

Rainbow is an optical phenomenon in meteorology. When sunlight hits the raindrops in mid-air, the light is refracted and reflected, forming an arched color spectrum in the sky.

Rainbow is a natural phenomenon, which is caused by the reflection and refraction of sunlight when it hits water droplets in the air.

Rainbow is formed by the dispersion and reflection of sunlight on small round water droplets in the air. When sunlight enters a water drop, it will be incident at different angles at the same time and reflected at different angles in the water drop. Among them, the reflection of 40-42 degrees is the strongest, forming a rainbow that people see.

In fact, as long as there are water droplets in the air and the sun shines behind the observer at a low angle, an observable rainbow phenomenon may occur. Rainbow usually appears in the afternoon, when the rain clears. At this time, the air is less dusty and full of water droplets, and one side of the sky is dark because of rain clouds. However, observers can see the sunlight without being covered by clouds above or behind them, so rainbows are easier to see. The appearance of rainbow is related to the weather change at that time. Ordinary people can infer whether it was sunny or rainy from the position where the rainbow appeared in the sky. When there is a rainbow in the east, it is not easy to rain locally, but when there is a rainbow in the west, it is likely to rain locally.

The visibility of rainbow depends on the size of water droplets in the air. The bigger the water drop, the brighter the rainbow, and the smaller the water drop, the less obvious the rainbow is. Generally, in winter, the temperature is low, there are few water droplets in the air, and there is less chance of rain, so there is generally no rainbow in winter.