Image statistics of measured and modeled cloud radiance are compared to evaluate the nature of radiance fluctuations. Images of aerosol and particulate clouds were obtained with the Atmospheric Transmission Large Area System (ATLAS). Radiative transfer model calculations were made for multiple scattering and emission in spatially inhomogeneous clouds of aerosols/particulates. Effects of spatial and time fluctuations, which are often neglected, are important because they may induce changes in background contrast and they affect the acceptability of simulated scenes.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.