2003 Volume 47 Pages 121-126
Taking account of the variation of the water vapor content and the temperature in the air parcel, a new model for the estimation of the cloud droplet size, the temperature and the saturation ratio has been developed by modifying traditional Kohler model for the equilibrium state. 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. Variations of size, temperature and saturation ratio with number density of CCN are simulated numerically. The results of simulations show that the temperature variation of the cloud droplet and air parcel is so small to change the values of physical properties but large enough to make the air parcel unstable (or convective) in the atmosphere.
