identification of low cloudiness areas to mapping of regions with high radiation across the country

abstract nowadays, solar energy as one of the most important sources of clean and free of damaging environmental effects energy are used in many cases including generation of electricity, heat and desalination of salt water. the purpose of this research is identification of high radiation areas as most suitable regions for these applications.to do this, cloudiness data of 120 synoptic stations were used to find the number of days with 0-2/8 cloudiness and calculate the average of monthly, seasonal and the annual of them over a period of 20 years (1989-2008). the statistical software of spss 16 was used to find the correlation equations of locations (latitude and altitude) with a mean seasonal (with r2 equal 0.81, 0.82 and 0.84 for spring, autumn and winter respectively) and annual number (with r2 equal 0.78) of days with low cloudiness. finally by the method of interpolation spline has been produced zoning maps of seasonal and annual high radiation areas of country. the investigation of average monthly amounts indicated that the most sunny days in april belonged to the baft, in may belonged to jask, in june belonged minab, in july belonged to dehloran, in august belonged mahshahr, in september belonged bushehr, in october belonged to kenarak, in november and december belonged to chabahar, in january and february belonged to saravan and in march belonged to chabahar. also in seasonal scale the cities of kahnuj, aghajari and chabahar in spring, summer, and autumn & winter respectively were most high radiation regions of country during this period. the study also found that 89 stations of 120 stations that studied, over 1989- 2008 in more than 200 days of 365 days on the year (more than 55 percent on the year), had clear and sunny sky and therefore most areas of iran have great ability to use renewable solar energy.