Histogram of resulting mean grain sizes (derived from moment K₁ at the outer model boundary; see Eq. (10) and text) for wind-forming models taken from Paper I, with M _⋆  = 1   M_⊙ and Δu_p = 4 km s^-1, spanning a range of stellar luminosities, effective temperatures and carbon abundances (see Table 2 in Paper I). The vertical dashed line marks a grain radius of 4 × 10^-6 cm where deviations in the opacity from the small-particle limit (SPL) may exceed 10% at wavelength λ = 1   μm (see Fig. 3).