天空漫射（Diffuse sky radiation）是阳光直接被地球大气层中的分子或悬浮粒子散射之后，才抵达地球表面的太阳辐射。它也被称为天光（skylight）、 漫射天光（diffuse skylight）、或天空辐射（sky radiation），是天空颜色变化的主因。来自太阳的阳光大约有总量的三分之二（根据在大气层中的灰尘和烟雾含量，在太阳高悬时大约为有25%的入射辐射直接被散射）会在大气层中被散射，最终成为弥散的天空辐射抵达地球。

在大气层中的重要过程是瑞利散射和米氏散射的弹性过程，光线的波长不变，没有被吸收，但从原有的路径偏折。

Diffuse sky radiation is solar radiation reaching the Earth's surface after having been scattered from the direct solar beam by molecules or suspensoids in the atmosphere. It is also called skylight, diffuse skylight, or sky radiation and is the reason for changes in the color of the sky. Of the total light removed from the direct solar beam by scattering in the atmosphere (approximately 25% of the incident radiation when the sun is high in the sky, depending on the amount of dust and haze in the atmosphere), about two-thirds ultimately reaches the earth as diffuse sky radiation. When the sun is at the zenith in a cloudless sky, with 1367 W/m above the atmosphere, direct sunlight is about 1050 W/m, and total insolation about 1120 W/m. This implies that under these conditions the diffuse radiation is only about 70 W/m out of the original 1367 W/m.