Insoluble Condensation Nuclei: The Effect of Contact Angle, Surface Roughness and Adsorption

Abstract

Condensation of water vapor an various surfaces was studied experimentally. For surfaces with an airwater contact angle θ less than 20° the experimentally determined values of critical supersaturation S_c. agreed with those given by the Volmer theory. At higher θ the experimental values of S_c. were below the Volmer theory values. When the applied supersaturation was less than S_c, condensation was avoided for periods as long as 20 h. Thus, if adsorption of water tends to negate the Volmer theory, the process is a slow one. It was determined both by experiment and theoretical analysis that the effect of surface roughness is to decrease S_c only Slightiy. These results suggest that most insoluble airborne particles are not likely to serve as cloud condensation nuclei.