Filling-in of spectral features observed in scattered sunlight and known as the Ring Effect has a significant impact on the retrieval of atmospheric trace constituents from both ground-based and satellite observations. As clouds also have strong impacts on radiative transfer in the UV/visible spectral range, possible changes of the Ring Effect due to clouds have to be considered. Such investigations require radiative transfer modeling explicitly accounting for both cloud and Ring features. UV/visible ground and satellite based measurements, taken under cloudy conditions, were used to validate Ring and cloud modeling using the radiative transfer model SCIATRAN. As an example results of model applications are presented for both ground-based and satellite geometry. Two case studies are used to explain the sources of the observed Filling-in. ¿ 2001 American Geophysical Union