meteorological optical range
length of the path in the atmosphere that is required to attenuate by 95 % the luminous flux in a collimated beam from a source at a colour temperature of 2 700 K
Note 1 to entry: The value of the attenuation has been chosen so that the meteorological optical range provides an approximate measure of the commonly used concept of meteorological visibility.
Note 2 to entry: The meteorological optical range,
These formulae are sometimes written
Note 3 to entry: This entry was numbered 845-11-20 in IEC 60050-845:1987.
Note 4 to entry: This entry was numbered 17-772 in CIE S 017:2011.