Preliminaries -- Scales, Tools and Reminiscences -- Observing Clouds and Their Optical Properties -- Fundamentals -- A Primer in 3D Radiative Transfer -- Numerical Methods -- Approximation Methods in Atmospheric 3D Radiative Transfer Part 1: Resolved Variability and Phenomenology -- Climate -- Approximation Methods in Atmospheric 3D Radiative Transfer Part 2: Unresolved Variability and Climate …