Abstract
An estimated monthly average of daily diffuse solar radiation on horizontal surfaces for a total of sixteen meteorological stations in Libya has been computed using the correlations of CitationIqbal (1979), CitationPage (1964), CitationCollares-Pereira and Rabl (1979), and CitationErbs et al. (1982). The data of bright sunshine hours and global solar radiation was obtained from fifteen of the meteorological stations during the period between 1981 and 1987. Data from the remaining station, at Tripoli airport, was obtained during the period between 1961 and 1990, and at only this location were true diffuse radiation measurements recorded. This measured data from Tripoli airport was then compared with the correlations of CitationIqbal (1979), CitationPage (1964), and CitationCollares-Pereira and Rabl (1979). Excellent agreement was found between the correlation of CitationCollares-Pereira and Rabl (1979) and the measured data.