DWD, Annalen der Meteorologie, 41, 2, 17 th International Congress of Biometeorology ICB 2005, p. 604-607 WEATHER RECREATION INDEX FOR EUROPE Krzysztof Blazejczyk Institute of Geography, Kazimierz Wielki University of Bydgoszcz, Poland 1. INTRODUCTION Tourism and recreation are important to national economies and personal income of its citizens. There is also increase in the number of people interested in tourism/recreation services. When choosing the location and the period of recreation we should consider climate and weather features. They are key for outdoor recreation abilities and they affect our satisfaction/dissatisfaction as well as human’s health (Blazejczyk 2000, Matzarakis and Mayer 1991, 1997). Favourable climate and weather conditions are essential advantages for recreational and tourism activity. However, in various European climates they are characterised by seasonality (Blazejczyk 2003). Various concepts and methodologies are in the use when considering bioclimatic criteria for tourism and recreation (Kozlowska-Szczesna et al. 1997, Mieczkowski 1985, Lee 1980, Maarouf and Bitzos 2001). The methods based on the human heat balance brought the new dimension in the research of man-atmosphere relationships (Blazejczyk 2005, Freitas 1990). Another approach in climate-tourism research considers the complex weather that influences human organism (Blazejczyk 2001, Freitas 2003). The aim of the present paper is to evaluate bioclimatic conditions of several sites in Europe for the needs of outdoor recreation. The seasonal fluctuations of weather that influence ability of outdoor recreation is examined. The new Weather Recreation Index is used in this purpose. 2. METHOD AND MATERIALS The research dealing with climate-recreation relationships should consider three categories of information (Freitas 2003): - aesthetic factors (cloudiness, visibility, sunshine duration, day length), - physical state of the atmosphere (precipitation, snow cover, wind, solar radiation, UV radiation, air pollution), - bio-thermal conditions (human heat balance considerations). According to this concept, the actual weather is one of the basic demand indicators of recreational potential of any time, season and/or region. To assess recreational potential of climate the bio-thermal classification of weather was used (Blazejczyk 2003). An analysis of the frequency particular weather components is the base of Weather Recreation Index (WRI). The index bases on two models (Blazejczyk 1987). The first one is multiply function: y = x z where x parameter represents quantity components of weather and z one the quality factors. The second is the model of system efficiency (Ef) based on the Ohm low. It assumes the functioning of any system depends on potential (P) and resistance (R) of the system components as follows: Ef = P / R. The final general model of evaluation considers both, potential and resistance features of quantity and quality components of weather: