sand and dust storms are natural events that occur widely around the world, mostly in dry and bare lands. over thepast decade a large part of iran has been affected by this phenomenon, and tehran has not been excluded from thisevent. therefore, having knowledge of spatiotemporal frequency variations can aid us in future management andstorm trajectory assessment. in this study the synoptic anemo...

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downbursts are small-scale, short-lived and energetic events in the atmosphere. they usually occur from the beginning of spring to summer when the weather is more humid and the convective weather conditions are suitable. because of the small-scale property of the downburst, it has sometimes been observed only in a meteorological station and other stations have not observed considerable changes....

extended abstractintroductionin the past decades, development policies in the country have caused negativeeffects on regions. these policies have caused the mass evacuation of ruralsettlement and the imbalance hierarchy of settlements. the reflect of these policiesare visible in the rapid and uneven growth of large cities and eliminate loops linkingbetween cities and rural settlements from the ...

during february of 2005 the north of iran witnessed the development and activity of a variety of severe meteorological systems accompanied with unusual heavy precipitation, mostly snow and hail. the rate and amount of snow in the northern coastal region was so heavy that it made a new record for that region with a report of more than 3m of snow in rasht, a city located in that area. also the da...

wind is the carrier of pollutants and any other gaseous or particle matters in the atmosphere. stable atmosphere with low wind provides favorable conditions for high contamination of pollutants in urban areas. the importance of mesoscale atmospheric flows in air pollution dispersion has been recognized in the past three decades and has been the focus of intensive research; both observational an...

introduction population growth, along with the rapid development in industrial and many urban sectors, and lack of sustainable development approach in urban planning are all caused great changes in environment in form of pollution and ravage. in urban environments, complexity of spaces and urban manmade phenomena as well as the lack of regular and continuous measurement of atmospheric elements ...