A study on the possibility of using cloud accumulation variable for calculating the total quantity of solar radiation falling on the Yemeni terrain

Abstract

In the limitation of gathering actual data of the total amount of solar radiation in the presence of clouds from the climatological stations in Yemen, other indirect methods were used to calculate them. A systematic method suggested by two researchers in the literature, viz., Liberlyand T. G., and Sarukinoi, L. I. were applied to give the possibility of calculating the solar radiation by using the actual cloud quantity “ns” available at the stations. This requires only the monthly data of the percentage of the cloud quantity that can be taken from the network stations (coordinates) without referring to the actual values of the cloud quantity of the specified climatological stations "n1".
 The results show that the percentage degree of deviation from the total quantity of solar radiation “QRns” when the clouds accumulate "ns" that were calculated using the method introduced by Liberlyand and Sarukinoi from the actual quantity of solar radiation “Qf” taken directly from the climatological stations for Aden, Riyan, Perim Island, Kamaran Island and Sana'a was , , , and respectively. 
 These percentages are within the allowable ranges for the theoretical calculations in the thermal energy. Consequently, the results give evidence of the possibility for using the total quantity of solar radiation calculated from the cloud accumulation variable “ns" with the use of the theoretical total solar radiation “QRn1” in any station in Yemen instead of “Qf” if its value cannot be obtained or due to the limitation of getting the value of the actual cloud accumulation “n1” in the climatological stations.