Mathematical methods and statistical distributions provide accurate results in climate calculations and hydrological processes. Knowledge of the probability distribution of rainfall provides a good basis for water resources planning. Due to the importance of rainfall distribution in economic, social, and especially agricultural studies, many studies have been conducted to estimate the probability of rainfall in various ways. In these studies, various probabilistic models have been used, and the results of most of the studies show the suitability of the gamma model, including the bivariate gamma distribution, for rainfall data. The bivariate gamma distribution is used in modeling hydrological processes. In the present article, assuming that they follow the bivariate Gamma Crowley model, after briefly explaining Y and X about the exact distribution of the functions U=X+Y, P=XY, Q=X⁄((X+Y)) and their related moments, the validity of this model was investigated for the data of the Rasht Airport Meteorological Station. The results showed that the rainfall data of this region also confirm the suitability of the bivariate Gamma Crowley model.