Effect of Graphitic Carbon on the Albedo of Clouds

We examine the radiative properties of clouds containing submicron soot particles as impurities. The soot particles are assumed to be distributed randomly inside water drops. The refractive index of this inhomogeneous mixture is evaluated using the mixing rule for a composite medium. Single and multiple scattering properties are obtained using, respectively the Mie theory and the delta-Eddington approximation. The presence of soot enhances the visible light absorption in clouds. A soot volume fraction of 7 × 10−6 in a model stratus cloud increases the value of the single scattering co-albedo from 10−7 (the value corresponding to that of pure water) to 10−3.