ATMOSPHERE - A DIFFICULT SYSTEM TO CONTROL

The control of the atmospheric system is extremely complicated by seve ral levels of complexity determining both experimental and model atmos pheric chemistry. This paper deals with the main aspects of this situa tion and shows the differences with water and soil environments. The f ollowing topics are discussed: the degradation lifetimes as basic to a ny control strategy; the chemical complexity of the atmospheric system and the related problems of reaction mechanisms, as a consequence of the enormous complexity; the planetary systemic processes produced; th e photochemistry and the night-time chemistry; the necessity of develo pment of high power models and of structure-reactivity relationships; the air pollutant transport problems, such as the internationalization of pollution and stratospheric ozone depletion; the atmospheric heter ogeneous processes, particularly in aqueous liquid phase of clouds and fog droplets; the atmospheric reactions as a function of. altitude, t hat determines a layer chemistry.