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Atlante climatico






Weather and climate



Weather: the physical atmospheric condition observed in the space-time environment.

Climate: the probability density function of several observations of the Weather.

Such a rigorous, technical and theoretical enunciation characterises the Climate as a probability expression that each individual weather instance has to occur on a geographically homogeneous region, during a specific astronomical, annual, seasonal, monthly time and, more generally speaking, over the ages. Climate is the resultant of the complex chemical, physical and dynamic system; the Climate System, as a part of the larger system composed by the Earth, considered in its wholeness, which is in turn a part of the Solar System, which is itself continuously growing. The Sun, the most important source of energy for the Earth, is in fact the most important factor influencing the Earth's Climate. Even though the simple theoretical definition previously stated is not directly usable because we don't have, a priori, the necessary integral physical knowledge about the condition and the evolution of the atmosphere, for this reason we have to adopt a practical one. The World Meteorological Organization (WMO), specialized agency of United Nations, operationally defines Climate, as the mean state of atmospheric physical parameters referred to a specific period of the time (year, month, etc.) for a defined geographical area, without the condition to limit the study to mean value parameters, but expanding the analysis to extreme values and to the variability of meteorological parameters. To reach this target, the WMO suggests meteorological data collection for climate purposes, over thirty years periods not overlapping each other. The current official Climate reference has been computed using parameter values collected in the range 1961 - 1990. If Climate is to be composed of constant data values, for the time interval of data collection, this solution would lead to results obtained using the epigraph theoretical definition. But Climate is never constant. Since geological ages it has been evolving, sometimes slowly or fast. Nowadays, also referring only to the mean atmospheric surface temperature, we can observe a shift in the measurement values, pointing to an on going climate variability. The climate evolves before us, changing more rapidly than what has until presently been observed, when climate evolution was observed only by the scientists and referred only to ancient times such as the ice-ages. The official thirty-year reference period therefore is too far from the present time. Comparison with present day weather events makes the several extreme meteorological parameters measured belonging to the climate different with respect to the thirty-year reference period. The scientific debate inside Italian Meteorological Service induced us to use, for operational resolutions, a new thirty-year range, from 1971 to 2000, closer to present time although overlapping by two third with the previous one, and therefore not fully comparable. For this reason we deemed necessary to publish our study results in this new Climate Atlas and it will be useful instrument permitting any reader to evaluate daily meteorological events. It will be a useful tool for decision makers in every human field that depends on Weather and Climate, both professional and recreational.

However it wouldn't have been possible produce this Atlas without the day and night weather observation and measurement work done by thousands of weather men that have worked in the Aeronautical Observatories during thirty-year periods in which meteorological data have been collected. Unfortunately we were not able to list the sequence of their names. For the readers it would be a long series of unknown names, but we, their colleagues, who have known them, it is a long series of friendly faces. We are grateful to them for the team and service spirit, for the working sacrifices, for their military discipline, and for the abnegation with which they have worked. We give a special thanks to Col. Tiziano Colombo, to Cap. Attilio Di Diodato and to MSgt. Nicola Bitetto for data analysis and editorial work. Without their activity, this work would never have been accomplished.

Col. Prof. Costante De Simone



I volumi dell'opera

CliNo period 1971-2000