With the help of a labelled diagram, explain why the sun appears reddish at the sunrise and the sunset.

Explanation

At the time of sunrise and sunset when the sun is near the horizon, the sunlight has to travel the greatest distance through the atmosphere to reach us. During the long journey of sunlight, most of the shorter wavelength blue-colour present in it is scattered out and away from our line of sight so, the light reaching us directly from the rising sun or setting sun consists mainly of longer wavelength red colour due to which the sun appears red. Due to the same reason, the sky surrounding the rising sun and settign sun also appears red. Thus, at sunrise and sunrise, the sun itself as well as the surrounding sky appear red.