Why does the sky look red during the evening & morning & pure blue during the afternoon?
Diffuse sky radiation, due to Rayleigh scattering (air molecules) and Mie scattering (dust particles). During the day, air particles scatter the Sun’s light, but they scatter light with shorter wavelength (blue) more strongly than light with longer wavelength (red). This results in the sky having blue colour. In the evening and the morning, the Sun is lower in the sky and its light has to go through more of the atmosphere. This results in most of the blue light being scattered away or absorbed, giving the Sun and the sky around it reddish or orange hues. The colour is more vivid in the evenings due to the increased air pollution (dust, smog, aerosol particles). Unlike Rayleigh scattering, which is produced by much smaller air molecules, the vivid red and orange hues in the evening are due to Mie scattering, which involves larger particles.
