Climatic change is a difficult concept to define. Clearly, it is related to the definition of climate. The first step in a study about climatic changes and its social and agricultural impacts is associated to the correct characterization of the weather variation. The climate study should not be dissociated from the dynamics of each element of the weather. The aim of this study was to characterize the monthly rainfall temporal distribution at Campinas, São Paulo State, from 1890 to 2005. In order to detect possible trends in the precipitation series, the 116 years were divided in four equally spaced periods (P1, P2, P3 e P4) which were compared among themselves then using the gama probability density function for 48 data sets (4 periods of each 12 months). The skewness level of the monthly precipitation series showed that the consistency of climatic water balance that uses monthly precipitations arithmetic means can be questioned in no significant trends were detected on the monthly rainfall time distribution at Campinas.
climatic change; climate; probability density function; climatic water balance
