Solar radiation reaches the earth's surface either by being transmitted directly
through the atmosphere ("direct solar radiation"), or by being scattered or
reflected to the surface ("diffuse sky radiation"). About 50 percent of solar
(or shortwave) radiation is reflected back into space, while the remaining
shortwave radiation at the top of the atmosphere is absorbed by the earth's
surface and re-radiated as thermal infrared (or longwave) radiation




The article includes howo radiation is distributed.
Albedo
Time of Day and year