Radiation Fog Processes (a field experiment in the Po valley)

In this last century the atmosphere has changed significantly. Human activities have profoundly affected the composition of the troposphere, the lower part of the atmosphere which is critical to the life of the planet. The troposphere can be seen as a highly complex reaction chamber in which trace compounds, emitted by anthropogenic and natural sources are processed and new species are produced. Fogs and clouds play a significant role in atmospheric chemistry, because are suspected of being the crucial link between emission of pollutants into the atmosphere and subsequent deposition to the surface in precipitation. A field experiment is described here, aimed at the elucidation of physico chemical processes occuring in fog. The experiment was carried out within the frame of the European project EUROTRAC, subproject GCE (Ground-based Cloud Experiment). In november 1989, several research teams from five European countries gathered for the full month at the field station of San Pietro Capofiume, In the Po Valley. This experiment is probably the most complete ever conducted In the field of fog chemistry. The experimental set-up and the experimental procedures are described In the film and the importance of this international collaboration is especially underlined. In fact, the study of physico chemical processes in the real environment requires expertise from a wide range of disciplines and a set of instrumentation usually not available to a single research group or institute.