Vertical density profile for a scale height of H₀ = 10, normalised to the midplane density, considering an isothermal model (solid line) and including an extended atmosphere as shown in Eq. (4) for ϵ = 2.5 (dotted line) and 4 (dashed line), corresponding to an atmosphere contributing above about 3–4 × z/h. The integral of the mass increase above 3 scale heights represents about 1 × 10⁻² of the total mass for ϵ = 2.5 and about 2 × 10⁻³ of the total mass for ϵ = 4, but strongly affects the radiative transfer in the upper layers.