Temperature structure differences between the ⟨3D⟩ and 1D model atmospheres for three values of α_MLT. The (T,τ) profiles for the [Fe/H] = −2.0 and −3.0⟨3D⟩ atmospheres have been averaged to produce the ⟨3D⟩ reference used in generating this plot. The outer atmosphere is not sensitive to values of α_MLT, while the deeper layers of the atmosphere are extremely sensitive to this parameter.