عنوان مقاله [English]
1- Introduction: although rainfall is regarded as divine blessing in most of the cases, if its volume, severity and form exceeds normal amount, then it is considered as a danger. Among the forms of rainfall, hail is the most dangerous one, however it hardly ever rains. The present research aims to analyze thermodynamically isometropia hail in Gorgan province in 12/ 10/ 2010 as a result of which not only agricultural areas, industrial areas, infrastructures and wildlife were damaged, but also 1500 residential units were demolished so that the insurance organization paid 485 million Tomans for the damage (a clerk working in the department of Accidents at the office of governor general of Golestan Proince).
2- Data and methodology: to conduct the survey climatic parameter data, satellite images and synoptic analyzed maps were obtained from Golestan meteorological office and both the raw data for providing isometropia maps of northern hemisphere in length ranges of 40-80 degrees west and 80 degrees east three days before hailing every 6 hours and the atmosphere data were gathered from the websites of NCEP/NCAR – NOAA, SCDC and the website of Wayoming university. Then by the help of Grads, Photoshop and Excel, maps and graphs were drawn and analyzed.
3 and 4- discussion and conclusion:
The system creating this shower as a result of the formation of a polar low pressure trough in 1000 hpa level or polar vortex in high levels and gradual deepening in later hours and days and then transferring into a short and powerful wave by earth movement and the fall of colder weather in higher altitudes to southern areas and intake from black, Mediterranean, Khazar sea and also thermal contrast with warm and humid weather of india ocean which has been brought by surface systems on the eastern north of Africa and south of black sea and east and south of Mediterranean sea formed a strong front and while passing the area under study the cold front quickly pushes southern warm and humid weather package to altitudes and forms a rather strong cumulonimbus cloud like an ocean one.