A formula is presented for the vertical decrease of water vaporpressure based on data from 103 radiosonde stations throughout thecountry. Annual mean value and monthly means for January, April,July and October of coefficients of vertical decrease in vapor pressureare calculated for the free atmosphere and along the mountain slopes.Factors affecting these coefficients are discussed. Classification and delineation of annual variations are made. On this basis a chartshowing the distributions of the decrease coefficients in both casesover the country is constructed. Finally analysis and comparison are made of the distribution patterns.