Orographically induced Convergence Lines
Development of convective cells and Cbs over mountain chains through confluence within a diurnal cycle.
The main reason for the development of convective Convergence Lines is the wind field pattern produced by changing thermodynamical situations in an orographic region during daytime. Convergence of the wind during daytime develops because of the differential diurnal heating of the mountainous area (mountain slopes and valleys). These meso-scale wind patterns are under the influence of synoptic scale wind. The orography changes the wind field in direction as well as in speed. Upward motions can be found in the regions of convergence. The strength of the upslope wind also depends on the climate of the area being observed. Mountains in moister climates, for example, have weaker diurnal mountain wind systems, because of the weaker sensible heat fluxes. For mid-latitudes these winds are the strongest during the warmer part of the year (mostly during summer months), and convective Convergence Lines can be observed mostly during this period.