Dust and light pollution

Abstract

A model for the prediction of the brightness of the night sky due to man-made light pollution by the addition of an ozone layer is refined by the use of a more accurate representation of the atmospheric molecular density variation as a function of height, and by using a better mathematical representation of the scattering angular function of aerosols. Each of these modifications leads to a small reduction in the predicted brightness of the night sky. This model adds a thin layer of dust of arbitrary optical thickness and height above sea level. Dust clouds at various heights and of various optical thickness are studied. Most calculations have used scattering and absorption coefficients appropriate for volcanic clouds; a few calculations refer to desert dust. Light pollution is reduced by a dust cloud of moderate density whose altitude is below about 10 km (for the V band) and increased for dust clouds at greater altitudes. Observations from good sites are not likely to be greatly affected by the increases in light pollution caused by volcanic clouds at altitudes of order 20 km.