Question

Rising and setting sun appears to be reddish because

• A. Diffraction sends red rays to earth at these times
• B. Scattering due to dust particles and air molecules are responsible
• C. Refraction is responsible
• D. Polarization is responsible

Answer 1

Answer: (B)

At the time of sunrise and sunset, the sun is near the horizon. The rays from the sun have to travel a larger part of the atmosphere, As ${\lambda }_b<{\lambda }_r$, and intensity of scattered light $\propto \frac{1}{{\lambda }^4}$, therefore, most of the blue light is scattered away, only red colour, which is least
scattered enters our eyes and appears to come from the sun. Hence, the sun looks red both at the time of sunrise and sunset.