What is the sign that the sky turns red?

The redness of the sky is a natural phenomenon of light scattering and refraction, and does not represent any sign.

The sky turns red because when the sun is active, high-energy particles will explode, which will interact with the earth's magnetic field and eventually emit different colors of light. Because the intensity of the sun burst was very strong at that time, blood-red aurora was produced. Because of the intense activity, the range of aurora has also expanded. It appears not only in high latitudes, but also in low latitudes. Or it is caused by the lighting of ocean-going fishing boats, and the air humidity is high, so the "blood-red night sky" is formed, which is actually a landscape combining human lighting with natural phenomena.

There are three conditions for the emergence of "blood-red night sky":

One is to have a red light for ocean-going fishing boats. The stronger the red light, the better the effect.

Second, the rainy weather environment, a lot of water mist floating in the air, high humidity;

The third is to watch from a certain height and angle.

There have also been places where the sky turned red: Zhoushan in Zhejiang and Fuzhou in Fujian.

The reason why the sky turns red in Zhoushan, Zhejiang province;

At that time, there was an obvious fog in this area, and the particles of this fog were relatively large and the concentration was relatively high, forming an aerosol. The light source may be the ship lights in the harbor, and these lights are not necessarily red. When the light is refracted and scattered by the fog, it is difficult for blue light and purple light with weak penetration to enter the human eye, while red light with strong penetration can enter the human eye, so people see the blood-red sky.

The reason why the sky turns red in Fuzhou, Fujian;

When the light in the rain and fog is red, the whole sky will turn red, and when the light in the rain and fog is green, the whole sky will turn green, especially at a certain height and distance. The scene was spectacular, and meteorologists also confirmed that it was raining in Fuzhou that night, with high air humidity and a lot of water mist, which created favorable conditions for the harmonious dispersion of red lights.

The earliest time when the sky turned red:

As early as the thirty-fifth year of Qianlong (1770), a large area of blood red appeared in the skies of China, Japan and North Korea. This phenomenon began in September 10 and lasted for 9 nights. Japan is the most prominent phenomenon.