Author's Name:	Husain Abodi, NaghamThari & Nagham Abbas
Subject Area:	Science and Engineering
Subject	Other
Section	Informative Article

Cloud cover, Correlation coefficient, Evaporation, Radiation, SODA data.

Cloud cover considered as the variable that highly impact on most of other meteorological variables, where it has an effect on radiation that imported to the boundary layer from atmosphere, and there for it control the energy in this range. The purpose adopted in this study depending on daily data for cloud cover and evaporation taken from Iraqi meteorological organization and seismology for period from year (2000) to (2005) of Baghdad city , and also solar radiation data for three component ( direct – diffuse – reflect ) and for the same location and period taken from European centre of solar energy services for professionals study (SODA) , the study extract monthly and annual mean to show the coherence between these three variables. When making the statistical operation and converting the cloud cover value to percentage of eight parts for showing cloud cover percentage and from making comparisons diagrams, the result shows that there is a high effect of evaporation process on cloud cover formation, where the high value of evaporation accompanied with the high cloud cover range and has a high positive correlation coefficient reaches (0.74) on some times. And the result also shows that the cloud cover inversely intense on direct and diffuse component of solar radiation to reach negative correlation coefficient in about (-0.93) as a highest value. This effect be less on reflected component, and in general it can depend on cloud cover to guess some other atmospheric variable especially on winter seasons.