This paper presents part of the research in the field of human bioclimatology and refers to biothermal conditions in different geographical environments in Serbia: an urban area and a mountain of medium height. The goal of the paper was to show bioclimatic differences during the summer between the city of Belgrade (116 m a.s.l.) and the mountain resort of Zlatibor (1498 m a.s.l.). The basic principle of bioclimatic analysis is the human heat balance between man and environment. This methodological approach is a combination of physiological and meteorological parameters that result in thermophysiological bioclimatic indices: heat load (HL) in man and the Universal Thermal Climate Index (UTCI). For this analysis, weather data for July, as the warmest month, was obtained, using daily meteorological data for the decade from 2000 to 2010. Results for July indicate a considerable difference between the two abovementioned environments. HL in Belgrade was dominated by degrees of comfort "hot" and "extremely hot, with the highest value of 4.540, while for Zlatibor the dominant degree of comfort was "warm". The UTCI in Belgrade has dominated by strong heat stress and moderate heat stress, compared to Zlatibor where the UTCI is dominated by moderate heat stress. In addition, a significant part of the monitored decade on Mt. Zlatibor was without heat stress, with the exception of 2006 and 2007, indicating favorable biothermal characteristics. Therefore, compared to Belgrade, with its considerably lower overall heat stress Zlatibor has the characteristics of a site with favorable bioclimatic qualities.

Abstract. The objective of this paper is to assess the bioclimatic conditions in Serbia during summer in order to identify biothermal heat hazard. Special emphasis is placed on the bioclimatic index UTCI (Universal Thermal Climate Index), whose purpose is to evaluate the degree of thermal stress that the human body is exposed to. For this research, mean daily and hourly (07:00 and 14:00 CET) meteorological data from three weather stations (Zlatibor, Novi Sad and Niš) have been collected for the period from 1998 to 2017. In order to identify patterns of biothermal heat stress conditions, the thresholds of the daily UTCI (UTCI ≥38 ∘C, referred to as very strong heat stress, VSHS) at 14:00 CET are compared with the thresholds of daily maximum air temperature (tmax⁡≥35 ∘C, referred to as hot days, HDs), which are further termed as heat wave events (HWEs). The findings show that the UTCI heat stress category “very strong heat stress“ at 14:00 CET indicates heat waves. The most extreme heat wave events occurred in 2007, 2012, 2015 and 2017. Moreover, three HWEs at Niš that occurred in July 2007 lasted 3, 10 and 4 d. HWEs and very strong heat stress events (VSHSEs) recorded in July 2007 (lasted 10 d each), 2012 (lasted 9 and 12 d) and 2015 (lasted 7 and 10 d) were of the longest duration and are considered to be the indicators of biothermal heat hazard. The daily UTCI14 h heat stress becomes more extreme in terms of severity and heat wave duration up to very strong heat stress.

The analysis of the bioclimatic conditions is becoming increasingly relevant in climate interpretations for human needs, particularly in spatial planning, tourism, public health, sports events, bio-prognosis, etc. In this context, our study presents general temporal bioclimatic conditions in Belgrade, defined based on the PET, mPET and UTCI heat budget indices. Monthly, seasonal and annual indices were analyzed for urban and suburban weather stations based on 43 annual sets of meteorological data obtained by hourly observations at 7 h and 14 h CET. This study aims to present the distribution of PET, mPET and UTCI indices to show the pattern of each index in a mild climate location and to examine annual and seasonal differences of each index in the Belgrade urban center and suburban part of the city. The study results indicate higher biothermal stress in the urban area compared to the suburban zone and that the indices are congruent during the summer. At the same time, during the winter, they are more difficult to compare due to their peculiarities becoming more noticeable. The results obtained of all mean monthly and mean annual values of all three indices clearly indicate the difference that follows the definition of the urban heat island (UHI), particularly those from morning observation and winter season. The UTCI index shows the most significant monthly, seasonal and annual difference between urban and suburban areas for both observations. The annual difference of ΔUTCI7h amounts to 1.5 °C is the same as the annual difference of minimum temperatures (Δtmin). In contrast, the annual differences of ΔPET7h ΔmPET7h are °smaller (0.8 °C and 0.7 °C) and closer to the annual differences of maximum temperatures Δtmax amounted of 0.6 °C.

The bioclimatic analysis of the central area of the city of Niš conducted in this paper is based on the use of the bioclimatic index Humidex, which represents subjective outdoor temperature that one feels in warm and humid environment. The purpose of this research is to observe the index change on a daily basis during the hottest part of the year (June, July, and August) over the period from 1998 to 2017. For the purposes of this analysis, hourly (7:00, 14:00), maximum and mean daily values of meteorological parameters (air temperature and relative humidity) were used, for the period of 20 years (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017), which were measured at Niš weather station (43°19'N, 21°53'E, at an altitude of 202 meters). The findings indicate a gradual change in the bioclimatic characteristics of this area during this period, especially over the last decade. After 2007 there has been a decrease in the total number of the days described as "comfortable". However, there has been an increase in the index values in all the other heat stress categories characterized by a higher or lower degree of thermal discomfort.

Outdoor tourism and recreational activities strongly depend on actual meteorological conditions. Traditionally, in three studied regions, the peak of tourists' streams concentrates in summer months. In the present study, we assess suitability of weather conditions for various forms of outdoor tourism in different regions of Serbia, Poland and Ukraine. Additionally, how the location of the station differentiates temporal patterns of weather suitability will be discussed. To analyse the suitability of weather conditions for various forms of outdoor recreation, we have chosen 23 meteorological stations of the national weather networks which represent different tourism areas and destinations. For each weather station, daily data for the period 2000-2017 of air temperature, relative humidity, total cloud cover and wind speed (at 10 m above ground) for 12 UTC as well as the daily maximum and minimum temperature, precipitation totals and snow cover depth were applied. Suitability of climate for outdoor recreation and tourism is assessed by the Weather Suitability Index (WSI) based on Błażejczyk's bio-thermal weather classification. The results of research show that passive forms of recreation (sun and air bathing) are preferred mostly in months from May till August or September. For the active forms of recreation, weather in summer months is very oppressive, especially in the resorts located in the south (Serbia, southern Ukraine). Active forms of recreation are preferred there in autumn, winter and spring months.

It has long been known that weather and climate have influence on human health and well-being. The human organism is in constant interaction with the environmental conditions. To access the atmospheric impact on humans, different methods in human bioclimatology are created. Most of them are based on human heat balance. In this paper it has been tried to present several bioclimatic indices based on the human heat balance according to the bioclimatic model menex (man-environment exchange). The aim of this paper is to present bioclimatic conditions in Banja Luka vicinage (Bosnia and Herzegovina) and to explore climate-recreation relationship. In the near vicinity of Banja Luka there are three spa centers that are favorable for recreation. For this analysis average available daily weather data for two extreme months (January and July, 1990) were used as well as the average monthly weather values for the period 1961-1990. The data were taken from Banja Luka weather station. As a result, several thermophisiological bioclimatic indices have been obtained. These are heat load in man, physiological strain, subjective temperature, subjective physiological temperature

The paper presents geoecological evaluation of the city of Loznica for the purposes of sports and recreational tourism based on quantitative method of diversity, V-Wert Method. Using the GIS tool by the quantitative method, the criteria of natural components (relief, forest, water surface and climate) are evaluated for the analyzed area. In the proposed method, the climate factor was supplemented by the analysis of the bioclimatic index Universal Thermal Climate Index (UTCI). When the evaluation was completed, the final results were obtained based on which the degrees of convenience of different parts of the analyzed area have been presented. Out of the total analyzed surface, which amounts to 705 km 2 , favorable surfaces comprise 21 km 2 (2.98%), and very favorable surfaces comprise 33 km 2 , i.e. 4.68% of the territory. The largest area consists of conditionally favorable terrains-333 km 2 (47.23%). Since one of the basic strategic priorities of the City of Loznica is improvement and development of sports and recreational tourism, the aim of this analysis is to emphasize the potential of the mentioned area in terms of general suitability of the terrain for the development of this type of tourism.

Abstract. The objective of this paper is the assessment of bioclimatic conditions in Sebia. A special emphasis has been given to the heat budget bioclimatic Universal Thermal Climate Index (UTCI) whose purpose is to evaluate degree of thermal stress that human body is exposed to during the last twenty years. In addition, the thresholds of daily maximum temperatures are analysed in order to identify increase and frequency of heat waves in Serbia. For this research, daily and hourly (07 h and 14 h) meteorological data from 3 weather station (Mt. Zlatibor, Novi Sad, Niš) are collected for the period 1998–2017. The results show that the most frequent UTCI heat stress categories are strong heat stress and very strong heat stress. The most extreme heat waves events are occurred in 2007, 2012, 2015 and 2017. Moreover, there were three Heat wave events (HWE) in Niš occurred in July, 2007 lasting 3, 10 and 4 days in row. Heat wave events (HWE) In July 2007 (10 days) and July 2012 (9 days) in Niš are occurrences with maximum number of days in row recorded.