An Analysis of Solar Radiation Data for Fort Collins, Colorado.

Work with solar radiation reaching the earths surface frequently requires a knowledge of the extraterrestrial solar radiation. A method of calculating extraterrestrial solar radiation over various time scales i.e. instantaneous, hourly, daily, etc. with known errors is detailed. Solar radiation data for Fort Collins, Colorado, for the years 1977-1980 are examined to determine extended periods of low surface solar radiation. During the 58 days from 5 January to 5 March 1978 the normalized direct component is shown to have been less than 0.15 for three separate periods totaling 29 days. From this same data set correlation equations between the hemisphericextraterrestrial ratios are developed, allowing prediction of the diffuse component, given the hemispheric, for this high altitude, dry environment. Author