Physical Geography Research
Year:2014 | Volume:46 | Issue:1|Papers Count:9

Introduction: In general, strength of rocky outcrops is associated with two factors, feature lithology that includes mineralogical composition, texture and rock Structure and environmental factors that is the area stones are located in (Hafezy moghadas, 2011, 229 after Ulusay, 1994). The mineralogical composition determines sensitivity of rocks against physical, chemical and biochemical attacks (Mahmoodi, 2010). Rocks because of containing different minerals show various stability against the degradation factors (Nikoodel, 2011). This is the first time research to use classification system of in geology for naming rocks to determine the degree of resistance of the stones against weathering and erosion.

Introduction: Atmospheric circulation patterns play the main role in the natural phenomenon occurring on the earth, especially in temperate regions. Some atmospheric circulation patterns cause wet periods and others cause low water and dried periods. Thus, because the annual occurrence of drought and wet events result from the general circulation of the atmosphere, recognizing atmospheric circulation patterns are explained, to some extent, for the possibility of evaluating these phenomena before occurance. Studies show that the floods and droughts phenomenan are influenced by atmospheric circulation patterns. Given the close relationship between the patterns and climatic elements, we can also attribute the extreme climatic events, such as floods and droughts, and dried and wet periods, to changes in atmospheric circulation patterns.

Introduction: Lakes are very interesting sedimentary environments for study of ancient climate changes in the environments and lake level changes. Lake Zeribar is situated in the province of Kurdistan, in the Zagros Mountains in three kilometers north-west of Marivan. The main purpose of this research is to study grain-size sediments accumulated in Zeribar lakes in order to check the water level fluctuations, climatic and environmental changes during the Holocene. Grain-size of the lake sediments is mainly controlled by the distance of the core site from the shoreline, the kinetic energy of the lake circulation and the source of the sediments (Lerman, 1978). The sediments sorting principle states that the grain size of lake sediments becomes finer and finer from the shore to the center, and sediment belts of different grain-size can be distinguished. Lake Zeribar sediments, providing a record of climatic variations more than 40, 000 years long, have been the subject of multidisciplinary investigations reported in several publications (among others: plant macrofossils by Wasylikowa, 1967, 2005; diatoms by Snyder et al., 2001; stable isotopes by Stevens et al., 2001). However, sediments of the lake have not yet been analyzed for grain-size, whereas it could reveal important information about the lake history and sedimentary process-geomorphology.

Introduction: Materials and surfaces with different thermo-physical properties provide variety of temperature patterns and temporal changes. Analyzing thermal behavior of the different land covers is one of the significant factors to determine urban microclimates. Urban land covers have usually high temperature. This can potentially increase the intensity of urban heat island effect and building cooling energy consumption and also change energy balance and heat fluxes in these areas.Therefore, regarding to the impact of surface temperature on changes of surrounding air components and formation of Urban Heat Islands (UHI), the main objectives of this study are including identification of the circadian pattern of surface temperature in different weather conditions and providing the best regression model to estimate surface temperature using air temperature.

Introduction: Lake Urmia, at the northwestern tip of Iran, is one of the largest permanent hyper saline lakes in the world and the largest lake in the Middle East. The lake is located between Eastern Azerbaijan and Western Azerbaijan, west of the southern portion of the similarly shaped Caspian Sea. It extends as much as 140km from north to south and is as wide as 85km from east to west during high water level periods. Because of being located in a dry and semi-dry region, this region doesn’t have suitable water resources comparing with global average water resources. Drought, climatic fluctuations, and shortage and disorder of rainfall cause many problems with regard to food and water for people who live in this region. Urmia lake is also one the most important and the largest aquatic ecosystems of Iran. The systemic and chain changes in the lake will lead to great effects on the climate and economic, social and hydrology conditions. Oscillations of the lake water levels and volume in recent years have attracted many opinions and created apprehensions.

Introduction: Drought monitoring and assessment is usually done through either ground observation or remote sensing. Due to having some limitations, gathering and analyzing ground observations are a time-consuming and expensive way to approach a precise drought monitoring and assessment. In contrast, remote sensing represents a fast and economic way of monitoring, but an applicable approach needs to be developed. To this end, using satellite sensor data which are continuously available provides cost-effective data for a better understanding of the region.They can be used to detect the drought commencement, duration and magnitude. Tropical Rainfall Measuring Mission monthly data (TRMM-3B43) and Monthly Normalized Difference Vegetation Index (NDVI) data of the MODIS on Terra satellite are freely available for this objective. The main objectives of the present study, which was carried out in the Fars Province, Iran, were: 1. integrating the satellite data for mapping drought severity classes using the Standardized Precipitation Index (SPI) and the NDVI anomaly maps, 2. creating drought risk maps, 3. calculating the percentage of drought affected area by drought risk level, 4. showing the effectiveness of satellite derived drought indices as an indicator for drought assessment, and 5. identifying the most drought vulnerable areas of the surveyed region.

Introduction: Climate have strong impact on tourism and leisure time. Climate as a natural environmental factor plays an important role in tourism development in different regions of the world. Climate change and global warming, due to increasing greenhouse gases have many effects on procedure of tourism areas. Evaluation of predictions on future climate change can reduce these effects on tourism industry. Unfortunately, despite the obvious importance of climate change on tourism, researchers have paid little attention to this topic until the 1980s. Thus, one of the oldest researches in this region is the examination about the impacts of carbon dioxide on earth warming and its effects on tourism (skiing Laavrntyds area) discussed by Boyle and Wall. This research has been done in Canada in 1980. In this study, climate change phenomenon has been examined using two scenarios A and B. The effect of climate change on snow condition, snow cover of the region, and ski industry were examined. The results show that this phenomenon has impact on the ski industry and shorten duration of the ski season. It should be noted that among researches carried out, a few of the issues of climate change was about the effects of climate change on tourism activities.

Introduction: According to General Circulation Model (GCM), zonal thermal belts are: 1. Inter- Tropical Convergence Zones (ITCZ) around equator; 2. Sub Tropical High (STH) belt around 30 degree latitude; 3. Sub Polar Low (SPL) belt around high latitudes. Inter- Tropical Convergence Zones belt has meridional migration on the different seasons and its position affects directly the situation of STH. The STH situation is the most important synoptic climatological pattern in Middle East and Iran due to changing season. The belt of Inter Tropical Convergence Zone (ITCZ) displaces in meridional path, about 5o over oceans and up to 40o in continents, during seasons of a year. The position of Sub Tropical High (STH) belt has been also affected by ITCZ movements. STH displacement may change the area covered by westerly Baroclinic Waves (BW) in temperate regions. The Northern Boundary Sub Tropical High (NBSTH) moves coincidently as the northern border of the STH belt. The position of the NBSTH is an important issue for changing precipitation regime and onset of precipitation events in Fars Province. The goal of this research is to determine the position of NBSTH over Fars in monthly scale during the period 1948 - 2010, undertaking its meridional displacement.