THE SELF-DEVELOPMENT PROCESS
NOTE THE SHORTENING OF THE HALF-WAVELENGTH BETWEEN THE TROUGH AND DOWNSTREAM RIDGE AXIS. THIS HELPS TO STRENGTHEN THE VORTICITY, VORTICITY ADVECTION AND THE UPPER LEVEL DIVERGENCE. THE SURFACE LOW DEEPENS, PRODUCING INCREASED WARM ADVECTION WHICH BUILDS THE SHORTWAVE RIDGE AHEAD OF THE TROUGH. THIS INCREASES THE AMPLITUDE OF THE SYSTEM.
From Kocin and Uccellini, 1990