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

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  • 1 Dept. of Mechanical and Aerospace Engineering, and Graduate Center for Cloud Physics Research, University of Missouri-Rolla 65401
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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 Sc. agreed with those given by the Volmer theory. At higher θ the experimental values of Sc. were below the Volmer theory values. When the applied supersaturation was less than Sc, 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 Sc only Slightiy. These results suggest that most insoluble airborne particles are not likely to serve as cloud condensation nuclei.

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 Sc. agreed with those given by the Volmer theory. At higher θ the experimental values of Sc. were below the Volmer theory values. When the applied supersaturation was less than Sc, 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 Sc only Slightiy. These results suggest that most insoluble airborne particles are not likely to serve as cloud condensation nuclei.

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