Synoptic climatology of fog in selected locations of southern Poland (1966–2015)

Abstract

Abstract. This paper investigates fog frequency in southern Poland in relation to various topography (concave and convex forms) and atmospheric circulation types. It also discusses long-term variability in the annual and seasonal number of days with fog. Daily information on fog occurrence was taken from three high quality synoptic stations representing various landforms: Kraków-Balice (bottom of the hollow), Katowice-Muchowiec (Silesian Upland) and Bielsko-Aleksandrowice (summit of Carpathian Foothill). In the central part of southern Poland during the last 50 years fog occurred on average during 53-67 days a year. The annual number of foggy days in Kraków (67 days) located in a structural basin was by 14-15 days higher than in Bielsko (53 days) situated in the Silesian Foothills. In the annual course, high fog occurrence (above 6 days per month) was observed from September to January, with the maximum in Kraków (10 days in October). At every station the monthly minimum of fog occurrence fell in July (2 days). In summer and spring the highest probability of fog occurrence was found on days with anticyclonic types and air advection from the northeastern (Na, NEa) and eastern (Ea, SEa) sectors. In autumn, a high probability was also found for the anticyclonic types with advection of air mass from the eastern and southern sectors. In the Carpathian Foothills (Bielsko) the probability of fog occurrence in winter was significantly enhanced only for the cyclonic types with air advection from the eastern sector (NEc, Ec, SEc) and nonadvective types Cc (cyclone centre) and Bc (cyclonic trough). Trends in the fog frequency were mostly insignificant. The only significant decreasing trend was found in Kraków on the annual scale and in summer when fog frequency was low.

Climatology of fog occurrence over a wide flat area in Serbia based on visibility observations

“…Hanesiak and Wang () found a decrease of the fog occurrence only in the northeast of the Canadian Arctic, while in the southwest part of this region the fog frequency increased significantly for all seasons. At the southern Poland, trends in the fog frequency for the period of 1966–2015 were insignificant in general, with the exception of the Krakow where the decreasing trend was observed (Lupikasza and Niedzwiedz, ). Hodges and Pu () reported significant variability in fog distribution among valleys in northern Utah (complex terrain) during the cold season when the frequency of fog was the highest.…”

A spatially explicit and temporally highly resolved analysis of variations in fog occurrence over Europe

“…Wanner, ; Houssos et al . ; Łupikasza and Niedźwiedź, ), even if local micrometeorological influences are found to be additional contributors to fog formation and dissipation processes here.…”

“…The basic fog-promoting properties of anticyclonic weather conditions in the lowlands, in contrast to cyclonic weather conditions, are also emphasized in field studies based on station data (e.g. Wanner, 1979;Houssos et al, 2012;Łupikasza and Niedźwiedź, 2016), even if local micrometeorological influences are found to be additional contributors to fog formation and dissipation processes here.…”

“…With a decrease in aerosol counts, this effect is diminished. Second, increasing air temperatures in the lower atmospheric layers, especially during winter, lead to the fact that the dew point is exceeded less often and so gaseous water vapour generally condenses less frequently to form fog (Gomez and Smith, 1984;Vautard et al, 2009;Avotniece et al, 2015;Łupikasza and Niedźwiedź, 2016;Veljović and Vujović, 2018). Although these studies cover long time periods, they are only based on station data with few measurements per day.…”

Thermal stress in the northern Carpathians and air circulation

“…In this paper, eleven circulation types were used, among which eight are advection types, two are non-advection types, and one is used in cases of unclassified situation or baric col ( Table 2). The Niedźwiedź classification was applied to analyze the impact of air circulation on different atmospheric phenomenon occurrences, for example fog (Łupikasza & Niedźwiedź 2016), precipitation (Twardosz 1999(Twardosz , 2007Kholiavchuk & Cebulska 2019) and secular changes in bioclimatic conditions (Błażejczyk et al 2003).…”