The relationship between drought and solar variables in some synoptic stations of Iran

Drought is natural phenomenon’s which can damage were and has a significant loss to human and natural structures. The occurrence of this phenomenon cannot be predicted with complete certainty. The main objective of this study is clustering of drought tradition stations and assessment Climate drought based on the triangular relationship between drought and Hydrometeorology and meteorology variables Such as rainfall, solar radiation and sunshine hours. In this study, using data from meteorological synoptic stations in Iran where twenty solar radiations were recorded, was conducted in the period 1970-2010.The stations studied using Minitab17 software based on the standardized precipitation index solar radiation and sunshine duration, Clustering, Standardized monthly precipitation and from each cluster a station were selected and to examine the relationship between drought and solar variables, and to examine the relationship between drought and solar variables the standardized precipitation same value curves map was drawn and then Angstrom equation variables such as solar radiation and sunshine duration as reference variables was drawn. The results showed solar variables divided into eight different Clusters in all studied stations coefficient of Angstrom equation 0.62-0.96 determinate except Bojnoord, Ramsar and Shiraz are 0.038, 0.067 and 0.36, respectively. The statistical mean period shows most station that started in March and continues in June, July, September, and October and continues in the late of November. In this period, the most sunshine hours and sun radiation are recorded.