Product of albedo ω, single-scattering polarisation p, and probability density function Ŝ₁₁ for the scattering angle θ = 90°. All quantities are calculated for a grain size distribution with q = −3.5, s_min = 5 nm and three different maximum grain sizes s_max = 100 μm (blue), 1 mm (red), and 10 mm (green) at a wavelength of 850 μm for astrosil; see Sect. 2.3 for the corresponding discussion.