The shape and color of the sun at sunrise and the changing sunset

Sunrise and sunset are red, because when the temperature is low in the morning and evening, the atmosphere is thick, thin and big, and the longer the wavelength, the easier it is for red light to diffract, and the shorter the wavelength of its light, the harder it is to diffract, so most of it enters the eyes and the sun we see is red.

When the temperature is high at noon, less particles such as red, orange, yellow, green, blue and purple can be obviously diffracted into people's eyes, and we can see the color of the sun.

Extended data

Sunlight contains various wavelengths of light: infrared, red, orange, yellow, green, blue, indigo, purple and ultraviolet. Light near red light contains a large proportion of heat energy, while violet light contains a small proportion of heat energy.

Eyes are often exposed to strong sunlight and are easily injured. Newton once looked directly at the sun for hours and almost blinded himself. Then he had to stay in a dark room for a few days to regain his sight. However, some people can look directly at the sun without hindrance. Shen Fu's Six Chapters of a Floating Life Childhood Notes said: "When I remember my childhood, I can open my eyes and look at the sun." Many people find the direct sunlight too bright uncomfortable, especially when reading white newspapers in the sun.

Reading in direct sunlight may cause permanent vision damage. In order to reduce the intensity of sunlight, many people wear sunglasses; Cars, helmets and hats are also equipped with goggles and other barriers to prevent sunlight from entering the eyes directly from a low angle. In some colder countries, most people like sunny days and usually avoid the shade.

In some hot countries, the situation is just the opposite. At noon, people like to stay indoors to keep cool. If they go out, they also like to stay in the shade, such as trees or umbrellas. People usually use shades, awnings, blinds or curtains to block sunlight from entering the room.