The effect of temperature and relative humidity on precipitation during recent decades (Case study: Zanjan station)

Temperature and precipitation are two important climatic variables that have a significant effect on life and activities of individuals. These two elements are generally dependent on each other. In this research, the correlation between temperature and precipitation is determined using Pearson correlation coefficient. The existence or absence of a linear relationship between temperature and precipitation was also examined. Furthermore, the simultaneous effect of temperature and relative humidity on rainfall was calculated and the significance of regression was investigated. In this study, SPSS software was used for drawing graphs and multivariate regression analysis. Using the findings of this research, it was shown that there is a weak inverse relation between temperature and precipitation. The actual contribution of temperature changes in precipitation is 3.61% which is very low, and there is no linear relationship between temperature and precipitation. In the two-variable regression, the temperature had again no significant effect on rainfall, but relative humidity was an effective variable in precipitation of this station. In this study, the mean annual temperature and precipitation of Zanjan station, extracted from the meteorological website, have been used during the statistical period of 1956-2005. Zanjan is located on the northern 36o41’ and eastern 29o48’ in the northwest of Iran. The city’s altitude at the station is 1620 meters.