Mo liwo ci Uprawiania Narciarstwa Biegowego w Rejonie Poznania w Kontek cie nie no ci Zim

The cross-country skiing is one of the most popular winter sport activities. It is a pleasant, easy and relatively cheap kind of sport and therefore, available for almost everyone. There are many attractive areas for cross-country skiing in Poznań and its vicinity. The urban green areas of Poznań are rather extensive (27.5%) and favourably located, with lots of footpaths and bicycle lanes, which make perfect skiing routes in winter. Poznań, as well as the most of Great Poland, belongs to the least snowy regions in Poland. However, this it must not prevent the citizens of Poznań from cross-country skiing. The analyseis of daily depths of snow cover in 37 winter seasons (1970/1971-2006/2007, December-March) have proved, that, on average, there are 13 days in winter with the amount of snow sufficient for cross-country skiing (the depth of snow cover ≥ 8 cm). This number varies greatly from year to year, the standard deviation equals 14.3 days and variation coefficient amounts to 112%. There were mild winters during the studied period, when the snow cover of the required depth appeared only for a few days or even did not appear at all (15 winter seasons). There also occurred very snowy winters, when skiing was possible for longer than one month (four winter seasons). The best conditions for cross-country skiing usually occur in the coldest winter months: January and February. The possibility of occurrence of the snow cover deeper than 8 cm is then 10-25%. Heavy snowfalls in Poznań do not happen too often and they require specific synoptic conditions. The most important conditions are low temperature and high humidity, which may appear under negative pressure anomalies over central Europe. Such anomalies indicate low pressure systems with atmospheric fronts moving over the continent and causing the air circulation from the northern or eastern sector.