1. introduction the position of iran in the subtropical region that has made its arid and semiarid climate and the topographic diversity changes this trend of climate. therefore, climate hazards such as frost, flood, dust storm, drought, temperature anomalies, heavy rainfall, avalanches, snow, sleet, etc occur in iran. the northwest of iran experiences the above conditions following the arrival...

dust storms are natural phenomena which occur in arid and semi-arid areas of the world. in this study, to evaluate the dust storms which occurred in mashhad over a period of 30 years (1981-2009), first, the number of days on which dust storms happened in mashhad (days with a wind speed greater than 15 m.s-1 and horizontal visibility less than 1000 m) were identified and counted for each month; ...

in the present study storms of the economic, political, and human dimensions of space (with the help of satellite imagery (modis, after a time, and the destructive power of hurricanes, including discussions of the factors influencing the formation dynamics, thermodynamics and environmental issues, snow storm 2005 investigated. for a more detailed analysis of synoptic snow storm of guilan, rasht...

The superior colliculus is organized into a superficial zone which is directly connected with other parts of the visual system and a deep zone which is not directly connected toith other visual centers. Within the superficial zone, there is a convergence of retinal and visual cortical afferents. The size, distribution, and synoptic patterns formed varies between animals. Removal of an eye in ne...

In our earlier work, components were considered self-contained logical theories, and composition was performed by simply including these theories in a larger KB, with suitable inference to account for interactions among components. In this working note, we sketch out a more general vision of components, which is more in tune with our original goal that they capture “cliches” or “patterns” of re...

introduction dust storms, one type of dust event, are in most cases the result of turbulent winds, including convective haboobs, which raise large quantities of dust from desert surfaces and reduce visibility to less than 1 km. this dust reaches concentrations in excess of 6000 mg m3 in severe events. the major dust source regions are areas of arid and hyper-arid, with mean annual rainfalls of ...