During sunrise, the light rays coming from the sun have to travel a greater distance in the earth’s atmosphere before reaching our eyes.
In this journey, the shorter wave length of lights are scattered out and only longer wavelength are able to reach our eyes. Since blue colour had a shorter wavelength and red colour has longer wave length, the red colour is able to reach our eyes after the atmospheric scattering of light. Therefore the sun appear reddish early in the morning.
