engleski

Impact of the large-scale wind and mesoscale shallow flows on the development of cumulonimbus clouds over Istria

An analysis of deep convective activity has been showed that the northeastern Adriatic represents the most convective area in Croatia. In particular, the Istrian peninsula. Every other day there was marked as a day with convection in the warm part of the year. Furthermore, in 82% of days with convective activity was observed during three dominant wind regimes on a large scale. They were from the SW (46%), NE (18%) and NW (18%) directions. Mesoscale local thermal-induced wind is also common in Istria, appearing every other day during the summer. Therefore here, with three selected cases (for every type of the dominant large-scale wind regime) we investigate the impact of jointed large scale wind and thermally-induced local wind on the development of cumulonimbus clouds. For this purpose we use the available measurements, satellite images and WRF numerical simulations at fine resolution. Among other, results indicate that the SW large-scale wind superimposed on the western sea breeze increases humidity advection at the foot of the mountains in the northeast of the Istrian peninsula. The large- scale NE wind is opposite to the dominant western sea breeze and prevents its deeper penetration over the peninsula. Nevertheless, the interaction reinforces the convergence of the flow field in the boundary layer and consequently the intensity of sea breeze fronts and its updrafts. The effects of NE and SW synoptic winds are somewhat similar. In all cases, the result is favorable conditions for the Cb development in the form of multi-cells.

large-scale wind; sea breeze; cumulonimbus

nije evidentirano