Visibility of Light Sources and Objects Through Natural Fog

Abstract

When observing an object through fog, its visibility is reduced by the scattering of the light emitted or reflected from the object. Our efforts have been rendered towards observing the physical characteristics when we view a light source or object through fog. In this paper, the practical comparison of some light sources such as a fluorescent lamp, a sodium lamp or a mercury lamp about visual conditions is made at night in fog on an experimental basis. The effects of color improved mercury lantern and sodium lantern, which are used practically in highway lighting are compared in fog, and visual ranges of colored objects on the road surface lighted by them are also measured. The most important result of the experiment is that the visual difference depending on various kinds of light sources can't be noticed so much as the large decrease of visibility by the fog itself. © 1965, The Illuminating Engineering Institute of Japan. All rights reserved.