This is a plugin material to simulate light scattering in the atmosphere. It is primarily intended for views from space. It can also handle views close to the ground and will produce acceptable sky colors and aerial perspective. But it does this quite inefficiently.
R9.6 (Windows/Mac, 32 bit)
R10 (Windows 32/64 bit, Mac 32 bit)
R11 and above (Windows and Mac, 32/64 bit)