Effect of Number Density of CCN on Equilibrium Radius and Temperature of Cloud Droplet during Competitive Growth

Abstract

Usually, for the estimation of the cloud droplet size in the equilibrium state, Kohler equation is utilized, assuming constant vapor content and constant temperature. However, the condensational growth of the cloud droplet consumes the ambient water vapor and releases the latent heat. Therefore, the ambient water vapor pressure and the temperature are changed. Taking account of the variations of the water vapor content and the temperature, a new model for the estimation of the equilibrium cloud droplet size and temperature has been developed by modifying Kohler equation. The modification of Kohler model is based on the mass and the heat conservation laws for the water (vapor and liquid) in the air parcel occupied by one cloud droplet. Variations of size and temperature with number density of CCN are simulated numerically.