The conversion of hydrophobic atmospheric soot to cloud condensation nuclei predicted using fractal and spherical particle representations. a, An anthropogenic-biogenic interaction scenario used in the PartMC-MOSAIC simulation (map data ©2024 Google). The pie chart shows the average total aerosol composition in the early afternoon. API1 and API2 are produced from -pinene; LIM1 and LIM2 are produced from limonene. b, Gas-phase concentrations of trace chemicals produced upon photochemical oxidation of anthropogenic and biogenic hydrocarbons, along with total vapor saturation, which is the sum of individual saturations of condensable species. The yellow band marks the time interval when the total saturation exceeded unity. c, Volume fractions of condensate modeled using three morphological representations of soot particles: fractal, spherical, and spherical coated with OC. For fractal soot particles, the filling angle of condensate is provided (see Fig. for its definition). Background gradient reflects the evolution in the total vapor saturation of condensable vapors during the day. d, The fraction of soot particles becoming cloud condensation nuclei at a water supersaturation of 0.2%, using three different morphological representations.