Top row: anisotropic ratio given by Eq. (47) for the different choices of τ. It represents the potential anisotropy of turbulence sustained by the vertical shear instability in the stably stratified differentially rotating medium. It is thus equivalent to the ratio between the horizontal and vertical turbulent diffusivities (D_h,v/D_{v, v}) when the latter is active. Bottom row: product of the thermal part of the Brunt–Väisälä frequency (N) by the computed turbulent characteristic time (τ). Both are shown at the same evolutionary stages and with the same colour code as in Fig 2.