Wilgotnosc wzgledna powietrza w warunkach srodmiejskich

Relative humidity takes not unworthy part in weather situations visibly conducive to growth of air pollution concentration. If it exceeds 70%, activation of SO₂ conversion can be observed, what in turn leads to hicher toxicity of this gas (fig. 1). It seems to be useful to make a through study of diurnal-yearly changes of relative humidity in the area of increased atmospheric pollution. Annual course of relative humidity has been calculated on the basis of an average for a ten year period (1961-1970) of mean daily values (fig. 2). The highest relative humidity occurs in the third decade of November (above 90%), and the lowest in mid June (about 60%). The threshold value of 70% remains common from the second decade of August until the beginning of April. Periods with increased humidity (f>70%) occur in cyclic (fig. 3). During the summer high humidity remains uninterruptedly not longer then two days, but in the winter it can remain most frequently for six to ten, or even for twenty six to thirty days. Values of relative humidity oscillate in range of 41 to 70% during the summer and 80 to 90% during the winter (fig. 4). Probability of relative humidity occurrence above 70% equals ca. 31% during the summer, but in the winter it can rise even to 84% (fig. 5).