EMPIRICAL RELATIONSHIP TO ESTIMATE GLOBAL RADIATION FROM HOURS OF SUNSHINE

A new set of constants for an Angstrom type correlation to estimate gl obal solar radiation has been found. Least-squares regression analysis is performed on solar radiation and sunshine duration data recorded a t Lucknow (latitude 26 degrees 45'N, longitude 80 degrees 53'E), India , to derive the new constants. These constants provide good estimates of global solar radiation with a maximum deviation of 9.67%. Statistic al comparison of the present results with the correlations of Bahel En ergy 11, 985 (1986); and Rietveld Agric. Met. 19, 243 (1978) shows tha t the new constants yield more accurate estimates. The Bahel er al. co rrelation of third order provides better results than their first orde r equation [7] and the equation of Rietveld 12, 131 (1987).