Physical Geography Research
Year:2015 | Volume:47 | Issue:1|Papers Count:10

Introduction: Lake Terraces are geomorphological evidence of climate change during quaternary. Location of these terraces location in different elevation shows paleo water lake level fluctuations. Investigation about Urmia Lake terraces was conducted by Bobek (1973).He found those terraces in 45-55 meter above Urmia water level on that time. According to Bobek, development of lake area in paleo Pleistocene period and cold Pleistocene periods was caused by reduction of temperature about 5 centigrade and reduction of evaporation. It is important that we don’t have any comprehensive investigation on Urmia lake terraces and many of these terraces and paleo shorelines remained unknown up to now. The aims of this research investigation of quaternary terraces of Urmia Lake represent their elevations and reconstruction of the areas affected by these fluctuations.

Introduction: The dust storms are one of the climatic hazards in the dry climates of the world. They cause many damages to the environment and humans. One of the aspects of a study to understand the origin of this phenomenon is the formation of foci in the recent years in the areas of research. It has been done in the central regions. The dust storms have gained global scale. This has demonstrated that the primacy of the Sahara has highlighted the importance of some other drylands, including the Middle East, Taklamakan, southwest Asia, central Australia, the Etosha and Mkgadikgadi pans of southern Africa, the Salar de Uyuni of Bolivia and the Great Basin in the USA).

Introduction: Iranian northern plain is surrounded by the Caspian Sea in North and part of the Alborz Mountains in South. These two geomorphologically distinct features have created unique climatic conditions. A plain lush with abundant rainfall is result of the proximity of these two distinct geographical regions. As a consequence, the Iranian Northern plain has been in use by human populations since the prehistoric times.The significance of coastal regions for human occupations has been documented all over the world. Abundance of food resources, access to the fresh water (rivers), and having clear landmarks have all made the coastal regions ideal geographical zones for human populations. In addition to that, proximity to the major water sources (big lakes, seas, and oceans) would regulate the climatic changes, and prohibits drastic alternations of the environment. Archaeological data have shown that coastal regions have also been used for human movements through prehistoric and historic times. Repeated exodus out of Africa is among such events.

Introduction: According to the definition of World Meteorology Organization (WMO), as the speed of the air mass is more than 30 meters per second, the jetstream will arise. The core of the jetstream is with baroclinic atmosphere due to the large difference in temperature and wind speed. There are two west jetstreams in the northern hemisphere. The northern jet stream is called polar front jetstream and the southern is called subtropical jetstream. Polar Front Jet Stream produce intense temperature gradient by polar air mass and tropical Polar Front Jet Stream is produced by strong temperature gradient of polar and subtropical air. The subtropical jetstream is produced by temperature gradient in tropopause as limited to the upper troposphere.

Introduction: Subtropical high pressure is one of the main elements of the general circulation of the atmosphere. Annual motion of the circulation plays an important role in movement path of pressure systems and westerlies. Hence, large parts of the planet are affected directly and indirectly by this system. Sometimes the high pressure called the subtropical high pressure belt. It’s shown as several cells within 15 - 35 north and south latitudes on the atmosphere map. According to the seasonal changes, the high pressure could be divided into 5-6 single cells. Saudi Arabia cell is one of the high-pressure cells in the cold period. It is generally an independent cell over the Red Sea to the Indian subcontinent and appears in warm period over the North-West of Arabian Peninsula, South West Iran and southern Iraq independently or as merged cells with Africa desert and Azores.

Introduction: Climate is a system consisting of atmosphere, lithosphere, cryosphere, hydrosphere, and biosphere. This system is involved in the exchange of energy and moisture among these five components. The exchanges link the atmosphere as the central component of the climate to other spheres. Changes do not occur separately in this system; rather change in one component contributes to reaction of other components. In synoptic scale, changes in each of these components cause changes in atmosphere patterns and changes in the climate of regions are affected by these patterns. In terms of climate, Iran is located in transition zone and influenced by different weather patterns in different seasons of the year.

Introduction: The Iran has vast areas of karst landforms due to the relatively high carbonaceous rocks deposited during different geologic eras. Karst landforms are noteworthy for investigation from many aspects. The primary importance of these regions is the considerable amount of underground water stored in karst formations. These reserves are favorable, both in quality and quantity, as natural resource for human. In addition to the studies performed to identify karstic regions of Iran, studying the geomorphologic aspect of karstic areas could be a noticeable contribution tothe studies related to underground water resources.

Introduction: Zayanderood basin is one of the major internal river basins in the central Iran, where Zayanderood River is the only permanent river. Fluctuations in rainfall in recent years have affected different areas of Iran. Because of the dependence of the provinces of Isfahan, Yazd, and Kerman on water resources of this basin, changes and fluctuations in precipitation within this watershed have had many social and economic consequences with bad outcomes in regional, national and international dimensions. Therefore, knowledge of mechanisms governing the procurement and availability of water resources in the basin can be helpful to develop strategies to deal with social and economic stresses. This can happen with more confidence, planning and proper management of water resources in the basin.

Introduction: Science of climatic design is defined as a set of theoretical principles and practical methods of management. The knowledge wants to provide a suitable living environment leading to healthy life based on sustainable development and the coherence relationship between the concepts of climatology, architecture and urban design. This attempts to provide aesthetic elements as the main criteria for the development of cities along with making profound effects on the use of sustainable energy with thermal comfort and reduction of energy costs. Therefore, the metropolitan such as Tehran is evident in this case. In addition to loss of preparation in providing thermal comfort conditions in the space activities, no consistent pattern, standard and desirability are observed for the development of its space, except inspecial cases.

Introduction: Alluvial fans are depositional landforms developed on a confined channel emerged from a drainage basin, i.e. between a mountain range and a plain. An alluvial fan is a fan- or cone-shaped deposit of sediments crossed and built up by streams. If a fan is built up by debris flows, it is properly called a debris cone or colluvial fan. These flows come from a single point source at the apex of the fan. They move to occupy the positions on the fan surface over time. The fans are typically found where a canyon draining mountainous terrain enter out onto a flatter plain, and especially along fault-bounded mountain fronts.