Analytical study of the changes in the color of daylight due to sulfate droplets and soot grains in the atmosphere

Absorption of daylight by an atmospheric layer that comprises non-interacting water and sulfate droplets, interstitial soot grains, and composite sulfate-soot particles is determined by use of exact theories of Mie or extended-Mie scattering from all types of suspended particles. Interest is in the color of the sky, as observed from the ground underneath a light-absorbing atmospheric layer which has been synthesized as above. The end-result of the theory presented in this paper is the spectral radiant power distribution and the colorimetric features of daylight at ground level. The numerical application manifests that microlensing by sulfate droplets gives rise to enhanced absorption by soot grains, which results in attenuation and redshifts of daylight. An investigation is made of the changes in the color of the sky, as observed from the ground, due to pollution of the air by sulfuric acid and carbon.