Pojav znižane meje sneženja na območju doline Planice in Peči (Tromeje)

Abstract

V prispevku analiziramo padavinski dogodek v noči s 25. na 26. marec 2016 ob prehodu hladne fronte. Analiza temperaturnih razmer na proučevanem območju (dolina Planice in Peč) pokaže, da v času padavin v višinah pod 2500 m ni bilo hladne advekcije. Podatki kažejo celo rahel porast temperature. Vendar pa so v času najmočnejših padavin temperature na naših temperaturnih postajah padle blizu ledišča in za kratek čas je bil nad Planico oblikovan izotermni profil, tako da je za nekaj ur snežna meja dosegla dolinsko dno. Podatki tudi kažejo, da je v času najmočnejših padavin in ohlajevanja nastopilo skoraj brezvetrje, kar kaže na to, da sta dolinska atmosfera in atmosfera nad njo v smislu advekcije in posledično temperaturnih sprememb v času znižane meje sneženja povsem ločeni.

Latent cooling of atmosphere as an indicator of lowered snow line: Case study from Planica and Vrata valleys

“…Precipitation condition in Julian Alps are typical for mountain areas relatively close to the sea with significant precipitation gradients and high precipitation amounts which were discussed already in previous studies (e.g. Ogrin and Ortar 2007;Hrvatin and Zorn 2017) In Slovenia, a lowered snow line in certain valleys in the Julian Alps was investigated by Strle (2015;2018) and Strle and Ogrin (2016). Based on a three-year study of the phenomenon, we have obtained a large amount of data, presented in this paper.…”

“…A characteristic feature of a lowered snow line is that during the precipitation event in the valley it first rains, then an increasingly thick vertical layer of air is gradually formed with a temperature of 0°C or a few tenths of a degree above 0°C (Stewart 1992;Kain, Goss and Baldwin 2000;Lackmann et al 2002;Strle and Ogrin 2016). We therefore analysed temperature conditions during winter precipitation events at different locations and elevations in both valleys.…”

“…A lowered snow line is a local climatic occurrence that is especially common in Alpine valleys due to mountainous topography, but can also occur outside of the Alpine valleys and on the lowlands (Jaffe 1967;Steinacker 1983;Strle and Ogrin 2016).…”