The processing of water vapor and aerosols by atmospheric clouds, a global estimate

• Published in: Atmospheric research Vol. 38; no. 1; pp. 283 - 295
• Main Authors: Pruppacher, H.R., Jaenicke, R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.1995; Elsevier
• Subjects: Earth, ocean, space; Exact sciences and technology; External geophysics; Meteorology; Particles and aerosols; Water; Aerosols; Vapor; Clouds
• ISSN: 0169-8095; 1873-2895
• DOI: 10.1016/0169-8095(94)00098-X

Recent data published in literature on global cloudiness and precipitation as well as data on updrafts in clouds and their liquid water contents allow us to estimate the global turnover of water vapor and liquid water in the atmosphere. From these turnover rates the global average capacity of clouds to uptake, store and release atmospheric aerosol mass and the rate of wet deposition on the ground was estimated. The results of such an estimate suggest that clouds contribute significantly to the processing of aerosol material in the atmosphere as they constitute an important temporary storage location for it. Although the contribution of aerosol mass resulting from a single evaporation of the global cloud mass is small, the large number of evaporation-condensation cycles which the atmospheric cloud mass on global average undergoes causes that on global average the global cloud mass represents a transfer-source of aerosol material whose release strength is of the same order as the strength of the major net sources of aerosol material. Since this transfer source is located inside the atmosphere it contributes most probably as a space source significantly to the observed uniformity of the atmospheric background aerosol above about 5 km altitude. A comparison of the total release strength of aerosol material from clouds with the total source strength of aerosol material from the Earth's surface suggests that on global average an atmospheric aerosol particle, as sampled by an observer far from any specific surface source, has already been cycled 3 times through the global cloud system prior to sampling.