Total reflected flux, I_λ (top), polarized flux, PI_λ (middle), and degree of polarization, P (bottom), as a function of the planetary phase angle, α, of a planet, a circumplanetary ring, and the combination of the two. The fluxes are normalized to the total reflected flux of a ring-less planet at a phase angle of 0° at a wavelength of 0.55 μm. The line styles correspond to different single scattering albedos, ϖ, of the gaseous particles (except for the ring model). For a single scattering albedo of 1.0 and 0.6, the planet has a geometric albedo of about 0.72 and 0.17, respectively. See Sect. 4.1 for details.