| quotient of the vertical optical thickness of a turbid atmosphere and the vertical optical thickness of the pure and dry atmosphere (Rayleigh atmosphere), related to the whole solar spectrum
Note 1 to entry: The total turbidity factor can be expressed by
TL = (δR + δA + δZ + δW) / δR
where δR is the optical thickness with respect to Rayleigh scattering at the air molecules, and δA, δZ, δW are the optical thicknesses with respect to Mie scattering and absorption at the aerosol particles, to ozone absorption, and to water vapour absorption respectively.
Note 2 to entry: The total turbidity factor has unit one.
Note 3 to entry: This entry was numbered 845-09-87 in IEC 60050-845:1987.