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Using the wind vector fluctuations measured at a height of 69 m by a tridimensional anemometer, the standard deviations au and a, of the lateral and vertical distributions of the effluents emitted by an elevated continuous point source have been computed. Nearly 300 hourly tests covering most of the weather conditions to be encountered on the Mol site have been made, during which have also been determined the values of a stability parameter S defined as the ratio of the hourly mean of the vertical gradient of the potential temperature between 8 and 114 m to the square of the hourly mean wind speed at 69 m. The dependence functions uu op = f(S) are of the hyperbolic type for S > 0 as well as for S < 0; they apply for hourly mean wind speeds up to 11.5 m s-I. For the sake of simplicity and quick estimations of uu and a, for current practical uses, seven atmospheric stability categories have been defined with the corresponding median uu and a, values at different downwind distances z. When ti < 11.5 m.s-l, categories El to E, are differentiated by means of a parameter f. derived from S by f.= log,, [IS I .lo6]; category E, corresponds to the case of strong winds.The data obtained show that for downwind distances z up to 50 km, the standard deviations au and a, dependon z following a power law. The Yo1 theoreticalresults compare favourably with those found by means of field experiments carried out on the Mol site as well as elsewhere by other authors.

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Deposition of Atmospheric Pollutants, containing the proceedings of a colloquium held at Oberursel/Taunus, FRG, November 9–11, 1981, is divided into three main parts: dry deposition; wet deposition; and deposition on plants and vegetation. The 20 articles in the volume permit a fair survey of present‐day knowledge and will be a useful tool to all working on the topic. Pollution by deposition of either the dry or wet sort is very insidious; its importance only appears in the long range, when its effects are or are almost irreversible. That is why concern was so long in emerging from decision makers.