Entropic Suppression for Rain Nucleation and Drizzle Prediction

We develop a first-principles entropic suppression framework for droplet nucleation in clouds, unifying homogeneous, heterogeneous, and ice-phase pathways under a single suppression-potential formalism.We derive a continuum functional S[ρ_v, φ] whose saddle yields classical critical radii and free-energy barriers ΔG(r_c). By solving the associated Euler–Lagrange equations, we compute dimensionless barriers S*(S) and fluctuation-prefactors A, forming the nucleation rate:J(S) = A · exp[–S*(S)]Embedding J(S) into a 1D parcel model and 3D large-eddy simulation (LES) microphysics shows substantial improvements in drizzle onset timing and precipitation bias compared to classical Kelvin-based kernels.