Rainfall analysis is important in different domains such as: agricultural planning, water resources plannings, runoff prediction, climatological studies, environmental studies, stream flow estimation and human life activities. Variation of rainfall with space and time were studied in Duhok Governorate, Mean monthly, seasonal and annual values of rainfall were found in different weather stations (Duhok, Zakho, Semel, Zawaite, Sersing, Amedy and Akre station). Winter months represent about 45-55% of the total annual rainfall. The annual variability of rainfall in all these stations are high. Isoheytal method was used to estimate the mean monthly values and mean annual values of Variation of Rainfall with Space and Time in Duhok Government. ٣٣ rainfall over Duhok Governorate. Simple and Multiple Regression Equation were found between rainfall and different meteorological elements.

Model was used to estimatenet Net Radiation falling on horizontal surface in Mosul, Baghdad and Nasiriyah stations for the time series . Results showed that there is a sort of relatedness between estimated and measured incoming short wave radiation(Rs) in the three stations, where the values of mean absolute error (M.A.E.) is not exceed (11,14,24)% in Baghdad, Nasiriyah and Mosul respectively. Rn estimated by the Model appear that Mosul station gives the lowest values of Rn in comparison with Baghdad and Nasiriyah stations, this is due to the amount of incoming solar radiation reached the earth surface. Summer months in Nasiryiah gave also values of Rn lower than that in Baghdad because of the sand storm which domain during the summer months in Nasiriyah. Two linear Regression Equations were found, the first between net radiation and net incoming short wave radiation (Rn & Rns ) and the second between net radiation and net long wave radiation (Rn & Rnl ) in each of the three stations. The correlation coefficient (R) found in the first relation is very high and ranged between (0.98 -0.99 ), while the values of ( R ) in the second relation ranged between ( 0.67 -0.87 ). Liner Regression Equations were also found between Rn and meteorological elements (Temperature, Relative Humidity, wind Speed and Sun Shine Ratio ) in each of the three stations.