Aerosol formation threshold for hydrochloric acid-water vapor system.

The conditions under which liquid droplet growth (aerosol formation) occurs in the presence of the hygroscopic vapor, hydrogen chloride (HCl), are experimentally investigated. The HC1 vapor has no impact on the nucleation process itself. The HC1-water equilibrium tables accurately predict the conditions where droplet growth occurs for HC1 concentrations ranging from 10 to 40 mg/m3. In the presence of HC1, a relative humidity of 81% promotes droplet growth.