# 17-29-108

luminous turbidity factor

Tv

quotient of the vertical optical thickness of a real turbid atmosphere and the vertical optical thickness of the pure and dry atmosphere (Rayleigh atmosphere), related to the visible part of the solar spectrum

Note 1 to entry: The luminous turbidity factor can be expressed by

where Evs is the direct-beam illuminance on a horizontal surface (at the ground), Ev is the extraterrestrial horizontal illuminance, av is the luminous extinction coefficient, and m is the relative optical air mass.

Note 2 to entry: The luminous turbidity factor has unit one.

Note 3 to entry: This entry was numbered 17-743 in CIE S 017:2011.

Publication date: 2020-12