We present a new model of snow containing impurities (graphite carbon). Submicron-sized soot particles are supposed to be distributed randomly throughout the volume. Using the mixing rule for a dielectric constant of a composite medium, we calculate the refractive index of a snow-soot mixture. Then we obtain the single scattering albedo and the asymmetry factor. Using the delta-Eddington approximation, we determine the reflectivity (albedo) of a snow layer in the wavelength range 0.3 μm≤λ≤2.5 μm. The calculated spectral albedos and the deduced amounts of graphitic carbon agree well with field measurements.