Why is the sun red in the morning and golden at noon?

Because the height angle of the sun is relatively low in the morning, the distance of sunlight passing through the atmosphere is relatively long, and only red light with a relatively long wavelength can reach the ground, so the sun we see in the morning is red, while the height of the sun is relatively high at noon, and the distance of sunlight passing through the atmosphere is relatively short, so most of the light can reach the ground, so the sun at noon is very bright, but it looks not like golden yellow, but more like white, that is, white light.

When the sun is in the morning or evening, the height angle of the sun is the minimum value in a day, and when the sun rays reach the observation point, they are obliquely incident, and the thickness of the atmosphere passing through at this time is the maximum value in a day. The atmosphere has a weakening effect on solar radiation, mainly through reflection, scattering and refraction, which makes the weakened solar rays feel much dimmer.

The atmosphere scatters the blue-purple light with shorter wavelength in the sunlight most strongly, so our sky looks blue, which is the result of scattering some sunlight. In the morning and evening, the atmosphere is the thickest, and the blue-violet light is the strongest, while the red-orange light with longer wavelength has the strongest penetration and can be seen by human beings through the atmosphere. Therefore, the sun in the morning and evening is not only weak, but also red, orange and yellow.

At noon, the height angle of the sun is the largest in a day, the distance of light reaching the surface is also the shortest, and the weakening effect of the atmosphere is also the weakest. Therefore, the light of the sun is strongest at noon, and the white light it sees is usually called visible light. In fact, it is not white, but consists of seven colors: red, orange, yellow, green, blue and purple. In sunlight, seven colors can be separated by physical prisms, and so can the seven colors of a rainbow.