Finished with hurricanes, and now we will start on thunderstorms. Continue to read Bluestein. Started out of sequence with wave cyclones, then divergence, which relates to wind shear, all of which are ingredients for thunderstorms and ultimately, helps in our understanding of supercell thunderstorms. Contrary to popular belief, supercells are producers of the highest concentration of violence in our atmosphere, not hurricanes. Hurricanes produce violence over a large area, while supercells produce damage over a small area.
Divergence is lateral spreading air parcels.
When theres lateral spreading in the upper troposphere, at 30,000ft., air pushes up to replace the air coming apart at the top. Convergence below is less than divergence aloft due to friction at the bottom, creating a surface low. Both types create divergence but the difference is how nature creates the divergence. A straight line for the trough and a curly line for the ridge. Having drawn arrows of wind direction parallel to the low and contours, we can observe that winds east of the trough at the bottom of the low, spread out towards the ridge, like traffic divergence into three different lanes.