Gholam Reza Roshan - Assistant Professor, Department of Geography, Golestan University, Gorgan, Iran
Abdolazim Ghanghermeh - Assistant Professor, Department of Geography, Golestan University, Gorgan, Iran
Elham Neyazmand - M.Sc. Student, Department of Geography, Golestan University, Gorgan, Iran

One of the atmospheric hazards that seriously affect human life and health is the occurrence of thermal tensions and stress in the form of heat and cold waves. Iran is one of the areas of the planet that has climate variability due to its geographical characteristics; therefore, consequently, its different regions are not immune to heat and cold waves. On the other hand, Iran's climate variability is the factor causing the difference between thresholds of heat and cold wave occurrence for its different regions. Therefore, in this study, based on three different thresholds, spatial analysis of the frequency of occurrence of heat and cold waves has been done. Thus in this work, using average daily data from ۱۹۶۰ to ۲۰۱۴, PET (Physiological Equivalent Temperature) was used to monitor heat and cold waves of four stations in Iran. Results of this study showed that in the context of global warming, although significant differences in the frequency of cold waves cannot be seen, these changes are significant and increasing for the frequency of occurrence of heat waves of selected station.

Global warming, frequency of occurrence, Duration, thermophysiologic indices, temperature stress, Iran