Extended Data Figure 3. Theoretical dependence of ammonia ternary and amine ternary nucleation rates on temperature.

Modelled GCR nucleation rates as a function of temperature (left-hand scale) at 2.0 × 10⁶ cm⁻³ [H₂SO₄] and either 2.0 × 10⁸ cm⁻³ [NH₃] (blue curve) or 2.0 × 10⁸ cm⁻³ [DMA] (red curve). (A concentration of 2.0 × 10⁸ cm⁻³ is equivalent to mixing ratios between 7.0 p.p.t.v. at 255 K and 8.2 p.p.t.v. at 300 K.) The sulphuric acid–DMA nucleation rate relative to the value at T = 278 K is shown on the right-hand scale (dashed red line). In the sulphuric acid–DMA system a sticking probability of 0.5 is assumed for all neutral–neutral collisions, and 1.0 for all charged–neutral collisions.