The rainbow in the western sky shows the weather.

If there is a rainbow in the west, it means there are clouds and rain in the west, and it will soon move eastward and rain.

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 full of water droplets and there is almost no dust, and one side of the sky is dark because there are still 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.

Extended data

The principle of rainbow

1, the French scientist Descartes was the first to study rainbows. 1637, he published an article explaining that rainbows are formed by sunlight refracting and reflecting into water droplets in the air. But he doesn't know the color of Bai Hong, and he doesn't know why they are arranged in a certain order. It was not until Newton's prism experiment that the color of the rainbow was explained.

2. Shen Kuo wrote in Meng Qian's Bi Tan that "Hong, Japan, China and Shui Ying are also. Sunshine, rain and dew, both. " "Color" means many colors. The word "work" in the word "rainbow" means "artificial" and extends to the meaning of "regularity"; "Worm" means "dragon", and the combination of "worm" and "work" means "dragon absorbs water". Therefore, the rainbow is commonly known as "lever draft" and "dragon water absorption" among the people. People used to think that rainbows would suck water away, so when rainbows came, people would knock on pots and bowls to "scare away" rainbows.