Left panel: plot showing the difference of the gradient of the natural logarithm of temperature (T) and that of the mean molecular weight (μ) for models including different mixing processes: the green curve is for a model with microscopic diffusion, the blue curve is for a model with a constant turbulent diffusion coefficient and the red curve is for an exponentially decaying turbulent diffusion coefficient. Right panel: the gradient of the natural logarithm of the mean molecular weight and of the temperature for the same models as in the left panel, the colour code has been respected.