Why do people on earth look blue when they look at the clear sky?

Blue is seen on the earth because fine dust in the atmosphere reflects blue light.

Sunlight is the light emitted by nuclear reaction "burning" on the sun. It traveled a long distance to the earth and reached the ground after being filtered by the atmosphere. Its energy distribution in the visible spectrum is uniform, so it is white light. When the light changes with time and weather, it will directly affect the color of the image.

Sunlight is the light emitted by nuclear reaction "burning" on the sun. It traveled a long distance to the earth and reached the ground after being filtered by the atmosphere. Its energy distribution in the visible spectrum is uniform, so it is white light.

The light emitted by various light sources is different in length, intensity and proportion, forming different colors of light, which is called light source color.

The color of light source is an important factor that affects and determines the color of objects. 1666, isaac newton, a British scientist, made the first experiment to separate the solar beam with a prism, which proved that the white light of the sun is composed of various colors.

Sunlight is the most important natural light source. It shines on the earth and makes the whole world colorful. When the light changes with time and weather, it will directly affect the color of the image. Besides sunlight, there are other light sources, such as the light used in our daily life. This is an artificial light source, which is much weaker than sunlight and contains different proportions of visible light. Generally, the light emitted by incandescent lamps is often red and yellow, while the light emitted by fluorescent lamps is blue. Sunlight is an electromagnetic wave, which is divided into visible light and invisible light. Visible light refers to colorful rainbow light seen by naked eyes, such as red, orange, yellow, green, blue, indigo and purple in sunlight; Invisible light is invisible to the naked eye, such as ultraviolet rays and infrared rays.

The wavelength of infrared ray is 0.77- 1000 micron, which is divided into near infrared ray and middle infrared ray. Far infrared ray, etc. The wavelength of far infrared rays is 2.5-30 microns, accounting for about 20% of infrared light waves. After light is transmitted, refracted, reflected and absorbed by objects, only a small part still maintains the survival of all living things on the earth, including human growth and the continuation of life, so far infrared rays are called "fertility rays".