Figure 1
From: Air pollution mitigation can reduce the brightness of the night sky in and near cities
Angular distribution of scattered light intensity for light of wavelength (λ) 530 nm computed for a mixture of urban-dominated aerosol components (details are discussed in “Methods”). The number of scattered photons proportional to the differential scattering cross section39 is shown on y-axis relative to the number concentration of urban aerosols36. (A) Black crosses in the left plot indicate results for the baseline conditions. The plot demonstrates that an increase of the particle size by 20% (solid blue triangles), 50% (solid green circles), and 100% (hollow red squares) over baseline while holding the number concentration constant enhances the scattered light intensity in all directions. (B) The range of backscattering features due to the varying complex refractive index (\(m=n+i\kappa \)). The baseline conditions are for a mean refractive index \(m\) = 1.5 + 0.05i (solid black line with cross symbols). The scattered intensity drops when lowering \(n\) to 1.4 (blue stars) and increases when \(n\) is raised to 1.6 (green squares). Highly absorbing elements in the aerosol mixture flatten the scattering phase function at large angles (long dashed black line for \(\kappa \) = 0.2), which is contrasted by the results for non-absorbing particles (short dashed black line for \(\kappa \) = 0.0).
