Albedo ω times scattering polarisation P_sca for a grain size distribution as a functionof the maximum grain size a_max. This figure represents the grain size that contributes most to the polarised intensity. Left: scattering on oblate grains (c∕b = 1.5) perpendicular to the grain’s symmetry axis (Θ_sca,2 = 90°). Centre: scattering on spherical grains (c∕b = 1.0). Right: scattering on oblate grains (c∕b = 1.5); the grain’s symmetry axis is coplanar to the scattering plane (Θ_sca,2 = 0°).