Diffuse sky radiation

Diffuse sky radiation is solar radiation that reaches Earth's surface after being scattered out of the direct solar beam by molecules or particles in the atmosphere. It arises when sunlight is diverted from its straight line path through atmospheric scattering and absorption, with Rayleigh scattering and Mie scattering the dominant mechanisms that deflect light without changing its wavelength. Diffuse sky radiation is responsible for the color of the daytime sky and is typically measured as diffuse horizontal irradiance in watts per square meter.