Temperature and potential temperature profiles illustrating the deviation from the adiabatic behaviour. Left: vertical temperature-gradient profiles comparing the adiabatic (solid line) to the diabatic (dashed line), corresponding to the dotted and solid curves, respectively, in the left hand plot. The colouring indicates a separate simulation, each with a different initial deep-atmosphere temperature. Each of these profiles correspond to a data point on the curves in the left hand plot. The central temperatures show the largest deviation from the adiabatic profile. Right: vertical profiles of potential temperature for both the initial and final conditions of the T₀ = 2522 K simulation. The impact of the mean-molecular-weight gradient is to homogenise entropy.