Vertical heat flow ⟨Q_r/dt⟩_h in the first row (upward heat flow is positive); horizontally averaged Miles instability condition profiles ⟨Ri < Ri_c⟩h in the second row; and horizontally averaged absolute vertical turbulent heat flux −⟨F_eddy⟩_h in the third row. The coloured lines indicate the simulations with different T_int. The horizontal lines in the top figure show the lowest pressure of the near-adiabatic lines. The dotted and dash-dotted lines in the top figure respectively indicate the equatorial RCBs and the shallowest RCB for the related T_int. The solid, dashed, and dotted lines indicate Ri_c with 0.25, 1, and 10, respectively. The dashed and solid lines indicate the −⟨F_eddy⟩_h calculated with the advective and the total K_zz, respectively.