SOLAR-RADIATION DATA FOR AMMAN

Measured solar radiation data for Amman were analysed. It was found that the annual average of daily total radiation was 20.4 MJ/m2 while that of the diffuse radiation was 4.5 MJ/m2. The monthly average of total clearness index was found to vary between 0.564 in January and 0.757 in July, and that of the diffuse radiation between 0.32 in January and 0.163 in July. Further, the histogram of frequencies of total clearness index indicated that the likelihood of having cloudy days, clear days, and partly-cloudy days was 9.5, 12.4 and 78.1% respectively. Finally, generalized charts were generated for Amman to estimate the ratio of hourly to daily radiation.