GEOGRAPHY AND ENVIRONMENTAL HAZARDS
Year:2015 | Volume:4 | Issue:13|Papers Count:8

Introduction: Identification and analysis of time-series behavior of the climatic elements and processes upon them are the basic factors of climatology science and has an important role in management and environmental planning. In general, the behavior of climatic elements is observed in 3 forms: Trend, Oscillation and Fluctuation. These behaviors will help us to identify climate change better. Today by changing more the trend of climatic elements, climate change has become more important than previous years. But in between the climatic elements, it has been noticed less than the other elements such as water vapor pressure. The importance of water vapor is that this climatic parameter has an important role in explaining the climate change, because of 1) It is the main source of rainfall in all weather systems, 2) It supplies the latent heat in this process and controls the heat in the troposphere and 3) It is the intensify severe storms. Given the significant role of atmospheric moisture in the Earth's energy equilibrium, it can be helpful in explaining climate change. Therefore, this article tries to survey two time series behaviors of climate data; the trends and fluctuations in water vapor pressure. The Mann-Kendall test is one of the popular nonparametric techniques for explaining the trend analyzing in hydrological and climatic data. The spectrum analysis is one of the best methods for extracting and analyzing visible and invisible climatic oscillations with different wavelength. In fact, spectrum show the distribution of variance along the entire range of wavelengths in time series. So in this article, we want to analyze the trend by using the Mann-Kendall test and detect and identify the fluctuations and cycles of water vapor pressure time series by using the spectrum analysis...

Introduction: Natural hazards in rural areas are a major challenge and the control is important. Local methods are used for managing natural hazards. Natural phenomena occur in most parts of Iran. Rural areas are the most vulnerable and therefore hazards damage villages. Villagers employ a variety of methods to decrease damage. The government has tried to introduce new methods to reduce the risks. A combination of both traditional and modern knowledge plays an important role in the management of natural hazards in the villages. In some other areas, traditional methods are fading. Therefore, the aim of this study is to examine the role of traditional and modern knowledge in the management of natural hazards in the villages...

Introduction: Temperature effects on human activities and natural processes are undeniable. Temperature increase, in particular, in the form of heat waves affects all facets of life including architecture, welfare, transport, agriculture and industry. When the intensity and frequency of the waves are high, they can produce major problems. In recent years, the number and intensity of these heat waves has been increased in the world, so that it is one of the major causes of atmosphere related mortality in many countries. The aim of this study is to analyze the temperatures above 40°C and specify their synoptic patterns in the west of Iran using statistical-synoptic method...

Introduction: Extreme temperatures have adverse effects on natural and human ecosystems which are directly related to human life and climate well-being. The role of these temperatures in human activities and natural processes is undeniable. Temperature alongside rain fall is considered the most effective climate elements in determining the role and distribution of other elements (Alijani & Ghavidel Rahimi, 2008, p.86). Sudden and severe temperature changes have unfavorable effects on different creatures. Perishing in the above and below the temperature range of ecological conditions has adverse effects on changes in temperature (hot or cold wave)...

Introduction: The Siberian high (SH) is a quasi-stationary and semi-permanent surface high pressure system residing over the Eurasian continent during winter with its climatological–mean central pressure exceeding 1030 hPa. This most important atmospheric center of action controls the climate of a wide area of this continent. The SH forms generally in October mainly in response to strong radiative cooling over the snow covered Eurasian continent in the lower troposphere and persists until around the end of April in 90-110oE and 40-55oN Gong & Ho, 2002., Shahgedanova, 2002., Shahgedanova, 2002., Takaya & Nakamura, 2005). The Asian climate is mainly affected by the SHI activity at winter. Despite the prominence and large spatial extent of SH in the northern hemisphere, its spatial and temporal variations are not comprehensively known (Panagiotopoulos et al., 2005, p.1411). Global warming has been intensified in middle of the 1970s and significant changes of mean sea level pressure (MSLP) in the northern hemisphere and changes of atmospheric circulation on many regions (Nakamura et al, 1997., Trenberth & Hurrell, 1994., Wang et al, 2007) have been reported. A variation in temperature results in sea level pressure decrease according to barometric relation.

Introduction: Jet stream is a strong narrow current concentrated by strong vertical and lateral wind shears (Vasantha et al., 2002). According to World Meteorological Organization nomenclature, jet stream formed when the speed of wind greater than 60 knots or 30 m/s. The major characteristics of the troposphere and lower stratosphere in the vicinity of jet streams were pointed out by a group of meteorologists at the University of Chicago (Rossby, 1974; Rossby et al., 1974). These characteristics are the tropopause discontinuities, the intense horizontal temperature gradients considerably below the jet stream core, and the associated frontal systems (Endlich, 1953). Jet streams possess a considerable amount of kinetic energy with velocities comparable to horizontal phase velocities of atmospheric waves (Vasantha et al., 2002).

Introduction: Thunderstorms are one of the most important, abundant and uncontrollable weather climates which cause human casualties all over the world, as well as perish large quantities of crops and infrastructure developments each year. Just between 1953 and 1957 financial losses caused by the hurricanes in America were over 3.6 million dollars (Changnon, 2003, p.1231). Many storms with different intensities have been identified, while their horizontal range is several tens of kilometers, their vertical range is about 10000 meters, and their lifetime is 30 minutes (Henderson, 2006). Often, these storms are formed by cumulus, rainy cumulus and tower-shaped clouds. Due to excessive warming of surface, thunderstorms are usually developed either by air mass or air front, especially cold front. Therefore, thunder is formed by air mass or has frontal origin. Thunderstorm climate adventure, as part of natural climate in northwest of Iran. compels extensive social-financial and bio-environmental losses on the people, especially farmers and stockmen every year (Khoshhal Dastjerdi, & Ghavidel Rahimi, , 2007, p.101). Sari Sarraf et al. (2007, p.123) have studied showery precipitation in the southern part of Aras river, and concluded that the most important reason for showery precipitation in this area is mainly due to two factors: local instability (in warm seasons of year) and cold front coming (in cold seasons)...

Introduction: Long-term annual extreme climate events, especially temperature and precipitation, have generally been used as indicators for the assessment of climate change. One of the most changeable climatic variables in time and space is precipitation. There are great number of research papers focusing on extreme precipitation on global, regional and national scales have been written. The results of these studies of precipitation and extremes indicate that there are changes in intensity, amount, duration, timing, rate of precipitation and change on trend of extreme precipitation events (IPCC, 2007) and these precipitation irregularities and extremes are impacts of climate change. Change in trend of extreme precipitation events has caused change in severity, permanence, temporal distribution and rate of precipitation in many regions and can cause drought and floods or other hazards. Generally, study of extreme precipitations and their frequency is very important in order to understand why they happen and if there are some signs or particular periodicities. Moreover this kind of research is fundamental in order, first of all, to save human beings, but also to avert or to limit damages done by these extreme events (Boccolari & Malmusi, 2013).