Numerical simulations of cloud condensation processes

Abstract EN

Clouds are collections of tiny particles of water and/or ice that are large enough to be visible.

The two required ingredients for the formation of cloud are water vapor and aerosols.

The spontaneous growth of Cloud Condensation Nuclei (CCN) into cloud droplets under supersaturated water vapor conditions is described by classic Köhler theory.

The aim of this work is to model Köhler theory and investigate effects of mass, solubility, and composition of the CCN in the formation and growth of cloud droplets.

Sodium Chloride (NaCl) and Ammonium Sulfate ((NH4)2SO4) were used as a solute material.

The results showed that both mass and solute material affect the nucleation of cloud droplet.

Increasing mass of solute would increase the critical radius and decrease the supersaturation required for activating the droplet.

It was found that the use of NaCl produce critical radius larger than that of (NH4)2SO4 and the required supersaturation for NaCl solute is lower than that of (NH4)2SO4 solute.

This is due the fact that NaCl has lower molecular weight than (NH4)2SO4.

The results also indicate that cloud temperature has minor effect on the cloud droplet activation.

The model can be used to investigate more suitable solute materials to determine which is best for cloud seeding projects.