Rotational Raman scattering in the Earth's atmosphere explains the filling-in of Fraunhofer lines in the solar spectrum. Based on the versatile DISORT (Stamnes et al., 1988) radiative transfer solver, a new model including single rotational Raman scattering, has been developed and implemented into the freely available libRadtran radiative transfer package (Mayer and Kylling, 2005). The model is successfully compared against measurements of the differential optical depth for both optically thick clouds and aerosol loaded cases. Subsequently, the model is used for various sensitivity studies to investigate how clouds and aerosol affect the filling-in of the calcium K line.