Comparisons of urban and rural bioclimatological conditions in the case of a Central-European city

This paper examines the influence of a medium-sized city (Szeged, Hungary) on the bioclimatological conditions of human beings. With the help of suitable indices for the available data set, differences in the annual and diurnal variation of human bioclimatic characteristics between an urban and rural environment are evaluated over a 3-year period. These indices are the thermohygrometric index (THI, defined by air temperature and relative humidity), the relative strain index (RSI, defined by air temperature and vapour pressure) and the number of ”beergarden days” (defined by air temperature at 2100 hours). In urban and rural areas, ”hot” THI conditions characterize 6% and 1% of the year, ”comfortable” conditions 30% and 20%, ”cool” conditions 10% and 12%, and ”cold” conditions 54% and 66% respectively. Over longer periods (e.g. one, month) RSI remains below the threshold value for strong heat stress in the city. The monthly frequencies of beergarden days show that these days appears from May until October and the city has almost twice as many pleasant evenings as the rural areas. Consequently, the city favourably modifies the main climatological elements within the general climate of its region; periods likely to be comfortable are therefore found more frequently in the city than in rural areas. Received: 24 November 1998 / Revised: 14 June 1999 / Accepted: 4 August 1999