Shallow cumulus rain drop evaporation and isotope model notebooks

Julia functions model the thermodynamics, raindrop microphysics, and stable water isotope physics to predict the size and isotope concentration of raindrops as they fall from cloud base. The model implements a version of the Stewart (1975) and Craig and Gordon (1965) equations for flux of the isotope ratio from evaporating rain drops. Simulations are performed for rain drop size distributions and water vapor observed below shallow cumulus clouds (Sarkar et al. 2023), and for idealized experiments illustrating the roles of environmental exchange and distillation by equilibrium and diffusive fractionation. Improved numerics allow for finely resolving the effect of differential diffusion of isotopes especially as drops near complete evaporation.