Initial cloud droplet number concentrations in clean and polluted areas: Simulation by a condensation model and comparison with measurements

Abstract

Measured size distributions and chemical compositions of aerosol particles have been compiled from the literature and taken as input for an adiabatic parcel model. Using this model, cloud droplet number concentrations have been calculated for different geographical regions. The comparison of simulated and measured cloud droplet number concentrations shows a good agreement for stratus clouds. Here the simulated average number concentrations are approximately 80 cm −3 for clean maritime and polar areas and 200 to 300 cm −3 for polluted areas in Europe and North America. For small cumulus in continental areas, the calculated number concentrations are generally higher than the measured ones.