IIT JEE , AIEEE Forum - Physics , Optics - looks simple but isn,t so.why sun looks reddish at the time of sunset and sunrise?????

kimi

looks simple but isn,t so.why sun looks reddish at the time of sunset and sunrise?????

ashish_banga

Two factors combine to make the sky red at sunrise and sunset: gas molecules in the atmosphere scatter bluer wavelengths of light more efficiently than redder wavelengths; and sunlight travels a longer path through the atmosphere to reach your eye when the sun is lower in the sky.

When sunlight travels through more atmosphere to reach your eye, more of its blue light is scattered away from your line of sight, and so the transmitted light appears redder. At sunrise or sunset, the light you see has had most of the blue light scattered away, and so the sky appears red.

That the daytime sky is typically blue is also due to scattering. In the daytime, when you look in any direction except directly at the sun, you see scattered light. Since the atmosphere scatters blue light more efficiently than red, the sky looks blue.

learner

See the attached figure.

When the sun is at the horizon, the rays travel more distance through the Earths atmosphere.Hence they get scattered more, and red, having highest wavelength,travels faster.

When sun is overhead, it traverses less distance in the atmosphere and thus has less scattering.

This is also the reason why it looks bigger at sunrise and sunset.

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