683950.fig.004
Figure 4: Schematic model of a supercell thunderstorm (from [4]). The solid and broken lines are streamlines of air flow relative to the moving system. Stippled, gray, and black shadings represent areas with low, medium, and high water content, respectively. The white area inside the black shading has the highest water content in the system. The thick line with triangular forms represents a gust front. The air in front of the gust front is warmer than the air behind the front and this leads to the development of updrafts in front of the front. The air behind the front is colder than that in front of the front due to evaporative cooling, which develops downdrafts. These updrafts and downdrafts are connected to each other to form a circulation through divergence of air (centering in the area with “Divergence”) from the front part of the gust front to its back part and convergence of air (centering in the area with “Convergence”) from the back part of the gust front to its front part.