Diurnal and seasonal variations of precipitation are considered, and the contribution of dynamic and radiative-thermal factors to formation of the precipitation field is estimated using the parameter P, characterizing the fraction of precipitation formed due to unstable stratification in the near-ground atmospheric layer. Most often this fraction does not exceed 10%. The main role in the precipitation formation and in diurnal and seasonal (annual) variations of the precipitation amount is played by the dynamic factor, namely, vertical and vortex synoptic-scale motions.