i introduction convective systems are atmospheric events that are associated with hazardous consequences, such as strong wind drafts, lightning, heavy rainfall, hail, or even tornado. they are manifested in the atmosphere within a broad range of spatial and temporal scales. a convection cell is composed of two distinct regions: the actual convective part which consists of the coldest intense ve...

1. introduction the effect of climate of the earth's surface is the result of interaction of different levels of atmosphere and lithosphere. one of the factors which influences that interaction is the way the system pressure transcends it. in this way, the system pressure changes and can be changed and eventually may become an environmental hazard and geomorphodynamic phenomenon. hazards are an...

For a finite group $G$‎, ‎let $Cent(G)$ denote the set of centralizers of single elements of $G$‎. ‎In this note we prove that if $|G|leq frac{3}{2}|Cent(G)|$ and $G$ is 2-nilpotent‎, ‎then $Gcong S_3‎, ‎D_{10}$ or $S_3times S_3$‎. ‎This result gives a partial and positive answer to a conjecture raised by A‎. ‎R‎. ‎Ashrafi [On finite groups with a given number of centralizers‎, ‎Algebra‎ ‎Collo...

â â â  many of environmental conditions are explainable, either directly or indirectly with regard to topographical changes in pressure levels of high atmosphere. thus, studying this subject is great importance. in this article, after determining the threshold of flood in catchment, altitudinal data of 500 hp level for 44 storms generating floods during (1370_1384) were processed using the fact...

carbon and sulfur isotopic data are helpful in understanding environmental conditions under which soils are formed. soils from 18 sampling sites along a climotoposequence from higher laleh zar mountains (4,351 m above sea level with xeric-mesic soil moisture-temperature regimes) to shahdad depression (250 m above sea level with arid-hyperthermic soil moisture-temperature regimes) in kerman prov...