introduction one of the factors that affect the climate of arid and semi-arid areas is dust storm. numerical models are new methods for evaluation of dust storms which can also be used for forecasting dust storms. weather patterns that lead to dust outbreaks can be simulated using computer models that support a wide range of simulations related to the long-range transport, dispersion, and depos...

1. introduction dust phenomenon which occurs in arid and semiarid lands of the world is closely related to climatic characteristics of the region. according to the world meteorological organization (wmo), whenever wind speed exceeds 15 meter per second and horizontal visibility reduces to less than 1 km in a station, dust storm is reported (goudie & mideleton, 2006). great storms are created wh...

introduction thunderstorms of the most important, most abundant of the most severe weather hazard that each year, in addition to large quantities of crops and infrastructure development, causing human casualties are also around the globe. between 1953 and 1957 the financial losses caused by the hurricanes in america has over 3.6 million dollars (changnon;2003,1231).storms of varying intensities...

[1] The infamous dust storm over the thanksgiving holiday of 1991 that led to loss of life from numerous automobile accidents on Interstate 5 (I-5) has been re-examined. Pauley et al. (1996) conducted an earlier investigation of this dust storm following the tenets of Danielsen’s paradigm—a paradigm that links the tropopause fold phenomenon and a balanced thermally indirect circulation about th...

1. introduction in recent years, desert dust frequency has increased in the global system. due to lack of vegetation in the regions prone to dust, the earth’s surface air becomes warm enough in these regions, moves upward and causes a cold downward circular air flow when it collides with upper tropospheric winds. when these winds strongly hit the earth’s surface, they create dust storms (xuan e...

Analyses of more than 40 years of climatic data reveal intriguing spatial variations in climatic patterns for Beringia (North-eastern Siberia and Alaska), aiding the understanding of the hierarchy of climatic controls that operate at different spatial scales within the Arctic. A synoptic climatology, using a subjective classification methodology on January and July sea level pressure, and July ...

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; ...