because of the passing of the air systems, temperature changes are often very sudden and plants cannot adapt themselves to these fluctuations and get damage. because low temperatures have harmful effects on the agricultural productions, so, the investigation of these temperatures are very useful for predicting and preventing probable damages. in this study, for determining the time of the freez...

abstract: numerical weather forecasting models are used for forecasting and dynamic conditions analysis of atmosphere phenomena in recent years. this research investigates dynamic and thermodynamic conditions in heavier precipitation events in different synoptic patterns in the southern coasts of caspian sea using wrf model. database precipitation events were formed. super heavy and heavy preci...

heavy rains are one of the features of arid and semi arid climates which result in flood. this kind of rainfall originates from environmental and synoptic conditions. mediterranean cyclones are the major factor in heavy rainfall in iran, but these cyclones do not happen in some parts of iran such as southern and southeastern areas. in this study, it has been tried to pinpoint the synoptic reaso...

dust is a common atmospheric phenomenon in iran especially in central arid regions.  this severely affects environment as well as resident’s health. among the results of this phenomenon are respiratory diseases, bash radiation, accelerated soil erosion, desertification and degradation of ecosystems. some dusts are originated from local desert conditions but adjacency to neighboring countries de...

drought is a natural hazard that have in arid and semiarid areas more frequency. so the study and identify synoptic patterns affecting this phenomenon seems to be necessary. by using peripheral circulation approach, drought periods during the 30-year (2011-1982) in the six synoptic stations provinces of kerman, yazd and isfahan, which have a long-term cooperative period were calculated with usi...

Synoptic eddy–mean flow interaction has been recognized as one of the key sources for extratropical lowfrequency variability. In this paper, the underlying dynamics of this interaction are examined from the perspective of a synoptic eddy-induced dynamic instability. To delineate this instability, a barotropic model is used that is linearized with respect to a stochastic basic flow prescribed wi...