Cross-sectional snapshots of a DARWIN model for a C-type AGB star, with M_* = 1 M_⊙, log L_* ∕L_⊙ = 4.00, T_* = 2600 K, u_p = 6 km s⁻¹, and [Fe∕H] = −1.0 (SMC). Upper, middle, and lower panels: gas density, dust density, and velocity of the gas (negative velocity inward), respectively. The panels show atmospheric snapshots at maximum (left column, ϕ = 0.0) and minimum (right column, ϕ = 0.5) luminosity. The solid black line indicates the radius of the star, calculated from the Stefan–Boltzmann law.