Defined as the greatest distance at which a black object of suitable dimensions can
be seen and recognized against the horizon sky, or, in the case of night observations,
could be seen and recognized if the general illumination were raised to the normal
daylight level. The criterion of recognizing the object, not just seeing the object
without recognition, is used. Transmissometers, telephotometers and sun photometers
are devices used to measure the degree of
transmission of light. Nephelometers (integrating) are used to measure visibility by way of the
light scattering from aerosols in the air mass.
Source:
PAC, 1990, 62, 2167
(Glossary of atmospheric chemistry terms (Recommendations 1990))
on page 2218
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
https://doi.org/10.1351/goldbook.
