Występowanie opadów gradu na obszarze Niziny Wielkopolskiej

Abstract

This study is an attempt to present the geographical distribution of hail occurrence in Great Poland Lowland in the years 1966–1980. The analysis is based on the data published by PIHM/IMGiW (The Institute of Meteorology and Water Management) in its annals from 1966 to 1980. According to this data, the maps of the mean number of hail days, monthly and annually, were constructed in order to determine the places where hail occurs most frequently. Additionally, the months and stations with the highest number of hail days were selected, and the maximum number of hail days in all months and stations was indicated. The material examined by the author shows that in Great Poland Lowland the mean annual number of hail days varies from one (1) in the eastern and northern part to 5.1 near Leszno. Most of the hail cases occurred in March – when the number of mean monthly hail days amounted to one (1) –, January and February. That is quite contrary to the results of other studies as generally, in most of the cases, hail occurs in the summer (Koźmiński Cz. 1964, 1965, 1968, Tuovinen 2007, 2009). When it comes to a geographical distribution of hail, the area where this precipitation increased in frequency is within Leszno and Kalisz Uplands and near Poznań.