Zmienność czasowo-przestrzenna występowania trąb powietrznych w Europie i w Polsce w latach 1998-2013

Abstract

The aim of the work detailed in this article was to describe instances of tornadoes being reported in Europe and in Poland in the years 1998-2013. According to the relevant ESSWD reports (as confirmed and fully verified), 1772 tornadoes occurred in Europe, while 102 were reported for Poland. The largest number of reports concerned Germany, while numerous cases were also observed for the south-eastern part of the British Isles. These results are consistent with previous studies. Antonescu (2016) reports that most tornado reports in European relate to the continent’s northern and central parts. In Poland, it is possible to distinguish a characteristic belt of land along which tornadoes arise most commonly. This runs north-south from the western part of Podkarpacie, through the Silesian-Cracow Upland, the Małopolska Upland and the central part of the Central Polish Lowland, to the eastern part of the South Baltic Lake District. Lorenc (2012) takes a different position over this matter, stating that tornadoes in Poland occur most frequently from the Opole area through the Małopolska region, Central Poland, The Kutno Upland and the region extending from Mazowsze through to the Suwalki region. In the analysed period, tornado reports in Europe and Poland arose most frequently in the summer months (from May through to August). This is in line with the conclusions of Taszarek and Brooks (2015). In turn, Przybylak (2007) states that the period with most tornadoes starts in June and lasts through until August. In Europe, tornadoes are seen to form most often in the afternoon, as is the case in the USA. This common trait stems from the fact that convection only starts developing in the afternoon hours, when the ground is warm enough. This warms the near-ground layer of air and upward movements are initiated. There are exceptions to this rule – morning tornadoes, or even ones occurring at night (Przybylak, 2007; Lorenc, 2012). The average number of tornado reports in Europe amounts to 118 per year, a result in line with the assumptions of Wegener from the early 20th century. However, the present figure is well below the average of some 169 per year given by Dotzek (2003). Where force is concerned, it is weak and moderate tornadoes that dominate in Europe and in Poland, i.e. those of strengths F0, F1 and F2 (on the Fujita scale). A similar situation applies to the Torro scale, with the tornadoes observed most frequently being at the beginning of the scale, i.e. T0, T1 and T2. Poland and Europe experience tornadoes of strength T3 (in 11% of cases in Europe as whole, and 10% where Poland is concerned). In Europe there is a prevalence of tornadoes of path width not exceeding 100m, while the situates observed most frequently are ones in which tornadoes make their landfall and then trek south-west or west (in Poland mostly the south-west direction). Lowlands represent the form of topography most favourable to the occurrence of tornadoes.