STUDY OF THE SYNOPTIC SITUATION THAT FAVOR
THE FREEZING RAIN  IN NORTHWESTERN TRANSYLVANIA


NATALIA URBAN


Abstract. - Study of the synoptic situations that favor the freezing rain in Northwestern Transylvania. The paper discusses a study on the “freezing rain” and the spatio-temporal distribution of days with freezing rain in the northwestern region of Transylvania. For this study we have analyzed statistical data from 12 meteorological stations in the counties of northwestern Transylvania. The period for which the analysis is done is 36 years (1972-2008). There was a statistical processing of days with ice, analyzing the average number of monthly and annual distribution of areas with freezing rain and analyzing the thickness of the ice deposit, and also looking at the synoptic situation where was freezing rain on the relatively large spaces in the area studied. For this purpose we used data averaged NCEP-NCAR reanalysis. For an average circulation of the troposphere, since the winter air masses have a lower vertical development, geopotential surfaces were used at 700 hPa. To determine the average barrel near the ground rules have been used geopotential fields at 1000 hPa and the surface pressure field. Field analysis was also done at ground level pressure and temperature throughout the air column. The analysis of synoptic situation shows that this phenomenon occurs in most cases when there is a mass of hot air entering a cooler air mass and there is a corresponding trough for the one at the ground, favor the phenomenon on a wider range of northwest area.

Keywords: freezing rain, thermal inversion, Northwestern Transylvania

 

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