Knowledge of water cycle in the atmosphere is very useful for several climatological and meteorological applications. This work presents a forward model of atmospheric emission in clear sky conditions, over Mediterranean sea. Solving a polarized radiative transfer scheme, brightness temperatures at the top of atmosphere were calculated. By fitting such temperatures against those measured by he SSM/I microwave radiometer effective vertical profiles of atmospheric water vapor were retrieved. Eventually, total precipitable water values were estimated. These values were compared with those obtained through statistical well-known algorithms from SSM/I brightness temperatures. The reported procedure was applied on a dataset, made up of Mediterranean scenes acquired during summer. The present work showed the feasibility of obtaining total precipitable water estimates as accurate as statistical ones; moreover, this approach provides information about the effective vertical atmospheric temperature, pressure and water vapor profiles, that allows this procedure to be more flexible and reliable, both form a spatial and a temporal point of view. Therefore, we characterized the presented research, calibrating our procedure for the Mediterranean area: a relative poor region, as far as field observation are concerned.