In this article, for predicting the daily monthly rate of total solar radiation (global) on a horizontal surface for Baghdad city, simple relationships have been improved. For the period interval (1961-2016), the values of the daily rate of total solar radiation and the solar radiation period on a horizontal surface in Baghdad city were measured. To estimate total radiation by the duration of sunlight on the desired day of every month, the mathematical linear correlation developed by (Angstrom correlation) was used. For the models that have been obtained high value for the regression coefficient and give the greatest agreement to the measured values. In this study, the daily monthly rate diffused (scattered) radiations on a horizontal surface were evaluated with the help of measuring total radiation. It is clear from the results obtained that Baghdad city receives the highest amount of radiation on a horizontal surface in June, while the lowest amount of solar radiation possible in December.

In this article, for predicting the daily monthly rate of total solar radiation (global) on a horizontal surface for Baghdad city, simple relationships have been improved. For the period interval (1961-2016), the values of the daily rate of total solar radiation and the solar radiation period on...