Metingen van de schemering

✍ Scribed by door J.J.M. Reesinck

• Publisher: Elsevier Science
• Year: 1944
• Weight: 873 KB
• Volume: 11
• Category: Article
• ISSN: 0031-8914
• DOI: 10.1016/s0031-8914(44)80002-7

✦ Synopsis

The brightness and spectral brightness of the zenith sky during twilight in Holland, under various atmospheric conditions, for solar altitudes between +2" and -6", were measured with a Se-rectifier-cell and colourfilters. The results for a clear sky are given in table V. For days with a clear sky (H) or only with cirrus clouds (C) there is a correlation between brightness and colour, the relative amount of blue radiation being the largest on days with the smallest brightness (fig. ). In 5 7 a theory of the brightness of the zenith is developed under certain simplifying assumptions and compared with observations.