A description is given of the apparatus and method used to measure the spectral characteristics of daylight between 285 and 775 mμ. These measurements, extending over approximately seven months, were made at Pretoria on total daylight, skylight without sun, and south sky. Spectral energy distributions, CIE chromaticity coordinates, correlated color temperatures, and illuminance values were calculated. The total of 422 sets of spectral energy distributions were averaged into a number of different groups. The derived chromaticities were found to be much closer to the full radiator locus than those previously published, which had been obtained in the northern hemisphere. The ultraviolet content also proved to be relatively high.
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