At about seven o'clock in the evening, I looked at the sky and suddenly found something very important. The color of the sky has changed! Look at the time. If it had been before, it would have been dark by this time, but at this time, it was already bright and the wind was blowing hard. Occasionally, a few drops of rain beads fall on my face, and the thunder sometimes sounds loud and sometimes gives people a gentle feeling. "Hey? How did this happen? " I'm confused. It's definitely not that simple. At first, the color of the sky was dim, bright and bright. After a while, the color continued to change from yellow to red. After a while, the color began to darken, and slowly, it began to disappear into the sky, leaving only traces on the distant hillside. That's interesting. Nature is wonderful. This watch aroused my great interest, and I was determined to find an explanation.

By searching and studying online, I finally got the general idea of the matter. It turns out that the color of the sky has not changed, because the sky is colorless, but we can see that the sky is blue as a whole, which is because of the sun. When sunlight enters the atmosphere, colored light with longer wavelength, such as red light, has greater transmittance, and can penetrate the atmosphere and shoot to the ground, while violet, blue and cyan light with shorter wavelength is easy to scatter when it meets atmospheric molecules, ice crystals and water droplets. Scattered purple, blue and cyan light fills the sky, making it appear blue. I think the same thing, sometimes the sky appears red or yellow, should be related to scattering. I analyzed what I saw and took it as a hypothesis. To sum up, there are three points. First of all, it may be because of the atmospheric density of the gas layer. Second, it may be related to scattering. Third, this phenomenon is the combination of sunlight and clouds, and so on.

I started asking this question online, and finally I had several different opinions. For example, when there is more water vapor, the clouds will be thicker, and the reflection will be stronger at this time, and most of the visible light of the sun will be emitted, so the sky is yellow at this time; Some people say that it is the cause of scattering and refraction.

After further reading books and discussing with good friends, it is concluded that the red color that appeared at that time belongs to the sunset glow, and the reason why the sunset glow is red is that sunlight passes through the atmosphere obliquely, and air molecules, water vapor and dust particles in the atmosphere scatter and absorb light, which greatly attenuates the sunlight, and the light attenuation of different colors is different. Therefore, sunlight passing through the atmosphere presents different colors, and these rays are scattered by scattering particles in the atmosphere. Among them, the reason why the sky is yellow should have a lot to do with scattering. As mentioned above, it is composed of sunlight and clouds.

Unexpectedly, it takes so much effort to find information and think about a problem. The answer to a question may be only a few words, but the truth and knowledge contained in it are immeasurable, and the sweat paid by scientists is unimaginable. Those scientists have really made great contributions to mankind. The world is full of miracles, and suddenly I can't wait to come up with the answers to all the questions. It is with this in mind that I am more and more curious about nature. Anyway, I benefited a lot. Nature is an endless topic and a mystery that can never be explained!