Large ternary hydrogen-bonded pre-nucleation clusters in the Earth's atmosphere

► Ammonia is certainly capable of stabilizing large binary pre-nucleation clusters. ► The ammonia affinity exhibits a moderately strong inverse dependency on molar fraction of ammonia. ► In most cases, the attachment of H2SO4 to (H2SO4)n(NH3)m(H2O)k, is favorable thermodynamically. ► A fast transition of the Gibbs free energy changes to the bulk value is observed.