Measurements of Sky Luminance Distribution at Stockholm

Abstract

Measurements of the distribution of sky luminance have been made at Stockholm.The fully overcast sky appears to have the same luminance distribution in the latitude of Stockholm (60° North approximately) as it has in the latitude of London (50° North approximately), Washington (U.S.A.) (40° North approximately), and elsewhere. It would therefore appear that the Moon and Spencer formula for the luminance distribution of the completely overcast sky can be taken to apply to northern latitudes.The blue-sky brightness distribution agrees with other similar measurements and with a formula derived from first principles by G. Pokrowski, but less well with Pokrowski’s own modified formula which he adjusted to agree with measurements made in Moscow.