Key points are not available for this paper at this time.
Average spectral irradiance values are given for total daylight, skylight and south sky irradiances as measured during seven months at Pretoria. Special attention is given to values for air mass 1 to enable comparison with data obtained elsewhere. Some results are also given showing the attenuation of daylight irradiance due to smoke and other pollutants.
C.J. Kok (1972) studied this question.