عنوان مقاله [English]
In order to investigate the temporal and spatial distribution of relative humidity in Iran, the reconstructed data of monthly average relative humidity from NCEP/NCAR in the range of 45 to 62.5 degrees east longitude and 25 to 40 degrees north latitude were used. Every month, the necessary analysis was done. Based on this, the relationship between the spatial and temporal distribution of rainfall with pressure and precipitation centers in Iran was investigated. The results show that in the winter season, most regions of the country, except for the coasts of the Oman Sea and Bushehr province, have positive relative humidity in the upper levels of the atmosphere. And in this season, the country is under the influence of western winds. At the beginning of spring, the conditions are similar to winter, but at the end of spring, the negative temperature gradually spreads from the south and gradually covers the whole country. In the summer season, Iran has a completely negative temperature in the upper atmosphere, and in this season, the country is under the control of the high pressure center of the subtropical zone, and the rainfall in this season, except on the Caspian coast, where the precipitation mechanism is different, is Other parts of the country will stop and finally, in the autumn season, the positive temperature will spread again from the northern latitudes to the south and will gradually cover the whole country.