Human settlements, and especially, the large urban areas significantly modify the environment. Atmospheric composition near urban agglomerations is highly affected mainly due to industrial activity and road traffic. Urban smog events are common characteristics of large, very populated cities. Furthermore, artificial covers (i.e., concrete, asphalt) considerably modify the energy budget of urban regions, and thus, local climatic conditions. One of the most often analyzed phenomena related to cities is the urban heat island (UHI) effect.

Besides several detailed studies of UHI using ground-based measurements, a more effective tool became available with the use of satellite imagery detected by different sensors on board. MODIS (Moderate Resolution Imaging Spectroradiometer) is one of the sensors on-board satellites Terra and Aqua. They were launched to polar orbit as part of the American NASA's (National Aeronautics and Space Administration) Earth Observing System in December 1999, and in May 2002, respectively. Sensor MODIS is capable of viewing the entire globe daily with 1 km spatial resolution. In this study, measurements of sensor MODIS have been used to analyze the spatial structure of daytime and nighttime surface temperature of urban areas in Central Europe (Bucharest, Budapest, Warsaw, Vienna, Milan, Munich, Sofia, Belgrade, Zagreb). The results suggest that the UHI intensity detected in the selected Central European cities exhibits high variability. Monthly average values of the temperature differences between urban and rural areas range between 1°C and 6°C, the most intense UHI occurs in daytime in the summer period (May-June-July-August). Population of the cities (which is highly correlated with the industry) is the main factor of determining UHI intensity that is modified by orography.