A Comparative Study of the Theoretical and Actual Sunshine Hours and its Relationship to Climatic Factors in Iraq

This study deals with the comparison of theoretical sunshine hours (tsh) and actual sunshine hours (ash) in different meteorological stations in iraq, and its relation to climatic factors (maximum air temperature, relative humidity and wind speed), during the period between 1979 and 2019. the results indicate that the lowest monthly value of theoretical sunshine hours (tsh) was obtained at mosul station for the month of december with a value of 9.57 hours and the lowest monthly value for actual sunshine hours (ash) was obtained at mosul station for the month of january with a value of 4.5 hours. the maximum monthly value of theoretical sunshine hours (tsh) at mosul station for the month of june was obtained as 14.43 hours, and the maximum monthly value of actual sunshine hours (ash) at rutba station for july was obtained as 12.4 hours. the average annual values of theoretical sunshine hours (tsh) ranged between 11.77 hours - 12.15 hours, while the average annual values of actual sunshine hours (ash) ranged between 8.19 hours - 9.19 hours. simple regression equations were reached at the various study stations between theoretical and actual hours of sunshine and different climatic factors.