20 19-0 1-04 the creator of the staff quality science field of Beijing Jingyuan water co., ltd.
Science lovers report for duty.
Light is an electromagnetic wave. The light emitted by the sun is a mixture of colors (i.e. wavelengths). Among them, the wavelength of light visible to human eyes is about 360 to 780 nanometers. Visible light can be roughly divided into seven colors: red, orange, yellow, green, blue, blue and purple. Among them, red light has the lowest frequency and the longest wavelength, and has the best penetration (diffraction) to the earth's atmosphere.
Enjoy the sunrise and sunset in the morning and evening, because the sun is in a low position at this time, and the light emitted needs to pass through thousands of kilometers of atmosphere to reach our eyes. In this case, only red, orange and yellow light with the longest wavelength in visible light can pass through the atmosphere. What about other wavelengths of light? As they pass through, their energy gradually decays and is blocked by the atmosphere. The rising sun in the picture below is divided into three colors because of the different distance and composition of light passing through the atmosphere. The bottom has the longest crossing distance, and there are the most dust, moisture and water vapor impurities in the air, so only the red with the longest wavelength is left.
If you look at the sun at noon, the sun is in the middle of the sky, and light can only enter your eyes through the atmosphere of 300 kilometers. All wavelengths of light are mixed together, so the sun is white at this time (not recommended).
The earth's atmosphere is not pure, and the bottom atmosphere contains a lot of particles and water droplets. So red light with strong diffraction characteristics is very useful. For example, traffic lights, parking lights, aircraft navigation lights and tower warning lights are all red, so that people can see them in the distance.
I am a science lover, Zhang Beihai. I don't list formulas or pile up data, so that science is no longer boring. Welcome to click on the avatar to browse more articles and ask questions.
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