Air pollution is one of the most important natural hazards in cities that is one of the priorities of climate research.  In this research, synoptic situation of days polluted by ozone in Tehran have been studied and by environmental to circulation approach and cluster analysis. At first, was formed a matrix in 2417*41. Rows are indicated days and columns represent the number of stations. by cluster analysis and Ward method eight different clusters were identified. The results showed that the frequency of the ozone days have a seasonal trend and more can be seen in the first half of year in these cases the establishment subtropical high pressure in Iran. Therefore, cause the persistency of pollution in Tehran.
 

One of the most important parameters in maximal use of radiant energy is the proper deployment of photovoltaic. The purpose of this study was to determine the optimum setting and tilt for installing photovoltaic panel in Kashan city. For this purpose, using the Masters Gilbert physical relations and relationships, the radiation received on the surface of the panel is calculated. The results of this study indicate that the amount of radiation received on the collector's surface in the south and in different slopes, 64 percent of the time of year, is more than the radiation on the panel surface mounted in the direction of the southeast or west with different slope angles. The highest amount of radiation is in the Azimuth to the south at a gradient of 30 degrees and 40 degrees; Southwest Azimuth (30 degrees) is almost similar to the South Azimuth and only in the southeast west, in summer, glides near the verge, they receive more radiation than the south. The amount of radiation received on the surface of the panel in the direction of south east west (Azimuth 60 °) on different slopes in 87% of the year is greater than the radiation on the panel surface mounted east or west (90 ° azimuth) with different slope angles. By comparing the results, it turns out that the direction of the photovoltaic panel installation will change, as the south changes to the east or west, the intensity of radiation will decrease in the days of the year. The highest photovoltaic energy output in Kashan is in the direction to the south, and with the angle of installation of photovoltaic panel 30 degrees from the horizon line. The most suitable slope for mounting panels between 30 and 40 degrees was obtained from other slopes.

One of the most important energy sources in the world is solar energy, which is a renewable resource and does not cause any damage to the environment. Which all of these features justify using it as a clean energy source and economically viable cost.. Due to the relatively large area of the Iran in low latitudes and relatively dry climatic conditions, in terms of solar energy utilization it uses excellent conditions. Solar power plants are considered as power generation and transmission networks whose is important that the location features of their construction sites are effective in reducing the risk of investing in solar energy. In this study, using geographic information system and fuzzy valuation method for the criteria and method of weighing (AHP), was considered the potential of the Kavir & desert region and Makran coast for the purpose of obtaining energy from the sun. For this purpose, were used the 14 criteria related to the climatic, infrastructural, and technical and physical conditions of the area. In order to overlap the fuzzy layers were used the usual operators, Gamma, Product and also the Sum Weighted Overlay operator to compare and present the appropriate result. Each of the operators has a different sensitivity to the fuzzy overlap of the layers. For this reason, was considered the Gamma 0.9 operator, due to the high sensitivity for building power plants with high electrical power generation and the Sum Weighted Overlay operator, for the construction of smaller capacity plants. In the overlay map, using the Gamma 0.9 operator, about 2%, and in the overlay map with the weighted operator, about 33% of the study areas were found to be very suitable for the construction of solar power plants.

Drought is a natural hazard that annually causes significant economic, social, environmental, and life-threatening damage in vast areas of the Earth. The damages caused by this phenomenon are intangible but very extensive and costly, which, if necessary, remote sensing techniques can be a useful tool in monitoring drought due to high temporal accuracy, wide spectral coverage, ease of access, no need for atmospheric correction and ground referencing. In recent years, the province of Hamedan has faced many problems due to frequent droughts. Therefore, the present study focused on investigating and monitoring drought in Hamedan province using the Temperature Condition  index and its impact on the vegetation cover of the province using Advanced Very High Resolution Radiometer (AVHRR) and National Oceanic and Atmospheric Administration (NOAA) remote sensing data. First, the relevant data was extracted from the Nova star database, and finally, the spatiotemporal behavior of the vegetation cover drought index was examined on 1528 pixels in Hamedan province. The spatial resolution of the data used in this study is 4 kilometers.  First, the relevant data were extracted from the Navstar database and ultimately, the spatiotemporal behavior of the drought index and vegetation cover was examined. The results indicate that drought has significantly increased the vegetation cover of Hamedan province based on remote sensing data. Kendall's coefficients indicate the presence of decreasing trends in vegetation cover at a 95 Percent confidence level. Only in May, June, and December has there been a slight decrease in vegetation cover within the extent of drought in the province. The spatial behavior analysis of the drought index on vegetation cover showed that February, March, as well as April have experienced more severe droughts within Hamedan province.