[en] The atmospheric air Rn concentrations have been measured in two sampling points in Spain. These points show very different geographic and climatological characteristics. Hourly measurements were taken over a period of nearly one year. The study has been carried out on the results of both sampling points and contains the following aspects: (a) influence of the origin of air masses; (b) statistical analyses and Fourier series; (c) relationship between atmospheric air Rn concentrations and meteorological parameters; (d) relationship between atmospheric air Rn concentrations and Pasquill and Turner's stability indexes. These studies show atmospheric Rn dependency on the vertical stability of the lower atmosphere. The obtained results imply a more effective use of Rn as a tracer in areas with a continental climate rather than a coastal one. (Author)