FIG. 3.

The gas profiles for H₂O, CH₄, CO, CO₂, and C₂H₆ for planets with pCO₂ = 0.01 bar for CH₄/CO₂ = 0.1 (on the left) and CH₄/CO₂ = 0.2 (on the right). Also shown are the profiles for the haze particle number density (in pale orange). The CH₄/CO₂ = 0.1 haze profile is divided by 1000, and the CH₄/CO₂ = 0.2 haze profile is divided by 1 × 10⁵ in order to plot it on the same axis as the gases. The profiles in the right panel show larger amounts of CH₄, H₂O, and C₂H₆ above 60 km in altitude and illustrate how haze-induced shielding can prevent photolysis of these gases. The sharp decrease in haze particle number density between 60 and 70 km in the right panel shows where fractal coagulation occurs. The atmosphere above the fractal coagulation region is populated by spherical submonomer particles.