Półrolniczak, Marek2017-01-042017-01-042009Badania Fizjograficzne, Seria A, Tom 60, 2009, s. 115-132978-83-7654-057-30067-2807http://hdl.handle.net/10593/17158Relying on data concerning atmospheric pressure noted between 1951-2000 in Poznań, interdiurnal changes of the average atmospheric pressure has been addressed. In accordance with biometeorological literature, the following ranges of atmospheric pressure felt by the human organism are assumed: weak (the change of 1-4 hPa), moderate (5-8 hPa) and strong (> 8 hPa). Furthermore, an additional range of change was adopted for a situation when the change does not take place or is less than 1 hPa. This situation is considered imperceptible to human organism. In the present article the ranges of pressure change are treated as types of change and marked as: a (< 1 hPa), b (1-4 hPa), с (5-8 hPa), d (8 hPa). The adopted pressure change ranges are here studied in terms of the occurrence of various types of atmospheric circulation as well as in terms of the direction of air mass influx. The analysis that has been conducted demonstrates that the average values of diurnal air pressure changes, as well as of the frequency of days the changes, occur in a specific cycle within the period of the whole year. The largest interdiurnal changes, as well as the greatest number of days with significant fluctuations, take place in the colder seasons of the year. In contrast, the slightest changes and the highest frequency of days when the changes are insignificant or none occur in the warmer seasons of the year. The average annual value of interdiurnal pressure changes in Poznań is 4.4 hPa, which means that the average bioclimatic conditions occur within the scope of weak stimuli. During the entire year 27 days with a scope of imperceptible stimuli may be expected (type a), 196 days with the stimuli that are hardly perceptible (type b) and 92 days with the stimuli of average perceptibility (type c) and 49 with the stimuli of strong perceptibility (type d). The attempt to associate the diurnal changes of atmospheric pressure with types of atmospheric circulation and the direction of air mass influx have proved a vivid relationship between the cyclic types and influxes from the west and the frequency of day with high fluctuations of atmospheric pressure changes. The days with large interdiurnal pressure changes often coincide with cyclonal circulations: the north-west circulation of the type CB (more than 20%) and south-west of type D (about 10%). The days with no or little pressure changes coincide the following anti-cyclonal types: north-east E (21%), south-east and east Ei (10%) and west C2D (about 10%).polinfo:eu-repo/semantics/openAccessArtykuł