https://doi.org/10.1351/goldbook.L03525
The redirection of a light beam due to interactions with molecules (Rayleigh and Raman scattering) and aerosols (Mie scattering). Scattered light received at any point in the atmosphere (sometimes called sky radiation) is a very important component of the total radiation received from the sun; it is dependent on the solar zenith angle, elevation aerosol concentration etc.
See also: elastic scattering (in spectrochemistry)