Question

During sunrise and sunset, the sky appears red while during the day, it appears blue. Explain these natural phenomena.

Answer 1

1. Scattering of light is the process by which light gets deflected and diffused all over as a result of its interplay with tiny matter particles.
2. When sunlight enters the atmosphere of the earth, it interplays with atoms and molecules of different gases present in the atmosphere and gets scattered by the atmospheric particles.
3. The air molecules and other fine particles in the atmosphere have sizes smaller than the wavelength of visible light.
4. Therefore, these molecules and fine particles prominently scatter blue-violet light of shorter wavelengths.
5. Red-orange-colored light of longer wavelengths is scattered the least.
6. The scattered blue light enters our eyes and we see the clear sky be blue.
7. At the time of sunrise and sunset, the sun is near the horizon and light rays from the sun have to pass through a larger distance in the atmosphere.
8. Light of shorter wavelengths is mostly scattered during this passage and only the least scattered red light of longer wavelength reaches the observer's eyes. As a result, the sky and the rising sun or setting sun appears to be reddish.