Extended Data Figure 6. Nucleation rates versus relative humidity.

Neutral (J_n; circles) and GCR (J_gcr; triangles) nucleation rates versus relative humidity. The experimental conditions are 250–800 p.p.t.v. α-pinene, 30–35 p.p.b.v. O₃, zero H₂ or HONO, (1.1−2.9) × 10⁷ cm⁻³ HOM, 278 K and (0.5−1.5) × 10⁵ cm⁻³ H₂SO₄. All measurements have been corrected to the same total HOMs concentration (2.05 × 10⁷ cm⁻³) using the curves shown in Fig. 3. The bars indicate 1σ total errors, although these are not shown in the x direction because they are smaller than the symbols.