Global NEST Journal, Vol 12, No 4, pp 401-408, 2010 Copyright© 2010 Global NEST Printed in Greece. All rights reserved A COMPARATIVE STUDY OF HUMAN THERMAL COMFORT CONDITIONS IN TWO MOUNTAINOUS REGIONS IN GREECE DURING SUMMER A. KAMOUTSIS 1 1 Laboratory of General and Agricultural Meteorology A. MATSOUKIS 1,* Division of Geological Sciences and Atmospheric Environment K. CHRONOPOULOS 2 Department of Sciences, Agricultural University of Athens E. MANOLI 1 75, Iera Odos Str., 118 55 Athens, Greece 2 Laboratory of Physics, Division of Chemical and Physical Sciences, Department of Sciences Agricultural University of Athens 75, Iera Odos Str., 118 55 Athens, Greece Received: 09/03/09 *to whom all correspondence should be addressed: Accepted: 26/05/09 e-mail: armatsoukis@aua.gr ABSTRACT Human thermal comfort conditions were determined in two mountainous regions of Greece, Gerania mountains (MG) in east continental Greece, and mountainous Nafpaktia (MN) in west continental Greece. Both regions are unexploited with considerable tourist potential. Four sites in each study region were selected on the basis of different altitude. Air temperature and humidity, 1.5 m above ground surface, were recorded simultaneously every 15 minutes by sensors with dataloggers in selected sites between 23 June and 28 August 2007. Data of the above parameters were used for the calculation of the thermohygrometric index from which thermal comfort conditions were evaluated. Also, an artificial neural network model, was applied for the THI values evaluation at the highest examined altitudes based on the respective values of the lowest examined altitudes in both MG and MN. Results showed that from 09:00 to 20:00 h, MN was found to be more suitable, in relation to MG, for tourist and recreation activities at altitudes of 1338 m. At lower altitudes, both study regions could be proposed in an equal basis for the above activities during summer. Also, for the same period, thermal comfort conditions at the highest examined altitudes of MN and MG can accurately be predicted using artificial neural network models on the basis of those at lowest examined altitudes. From 21:00 to 08:00 h, MN can be considered clearly as a better tourist destination than MG. KEYWORDS: thermohygrometric index, artificial neural networks, mountainous Nafpaktia, Gerania mountains. 1. INTRODUCTION Mountains are integral and important parts of the climate system (Beniston et al., 1997). Meteorological factors such as the solar radiation, the air temperature and the humidity in combination with the intense relief, different slopes, orientations and other topographic irregularities results in a variety of microclimates in mountain regions (Barry, 2001). Mountains are, in general, one of the most popular destinations for tourists (Nepal and Chipeniuk, 2005). The air layer conditions near the ground up to 2.0 m affect strongly the human activities (Yilmaz et al., 2007) which are related closely with thermal comfort conditions. Thermal comfort is defined as a condition of mind in which satisfaction is expressed with thermal environment (ASHRAE, 1966; Oliveira and Andrade, 2007). One procedure for the assessment of thermal comfort conditions is based on the use of biometeorological indices (Matzarakis, 2007) which usually require multi-variants (Toy et al., 2007). A relative index, the thermohygometric index (THI) provides a more detailed approach to summer thermal comfort conditions in mountain areas when the available data are air temperature and