Abstract

This research focuses on the calculation and analysis of the atmospheric clarity factor for the city of Mosul, located at the intersection of latitude (36° 19' N) and longitude (43° 09' E) at an altitude of 223 meters above sea level. The study covers the period from 1980 to 2022 to determine the amount of solar radiation reaching the Earth's surface and its relationship with selected climatic factors. These factors include total solar radiation, relative shortwave radiation, actual and relative sunshine duration, air temperature, relative humidity, cloud cover, and dust storms. The annual and seasonal variations of these factors were plotted, and statistical graphs of the variations in the atmospheric clarity factor (Kt) were created alongside the selected climatic factors and others. Equations were derived to calculate the values of the atmospheric clarity factor (Kt) based on these climatic factors, with high correlation coefficients for most of them. The calculated values of the atmospheric clarity factor (Kt) were compared with measured values and presented in separate tables. The study revealed that the highest value of (Kt) was recorded during the summer months, while the lowest values were recorded during the winter months, due to the increase in cloud cover and relative humidity in the atmosphere during the winter.