Isotope Rainout: Rayleigh Distillation of δ¹⁸O

Follow a single moist air mass as it drifts from the open ocean toward an inland mountain range. As it rains, it loses water — and because the heavier water isotope H₂¹⁸O condenses first, the vapor that remains airborne (and every raindrop that follows) becomes progressively lighter isotopically. This simulator computes that process step by step with the real Rayleigh-distillation equation and the Majoube (1971) temperature-dependent equilibrium fractionation factor, tinting the cloud and the rain by their live δ¹⁸O value so you can watch the "continental effect" and "altitude effect" that hydrologists actually measure in real rain samples.