Space Science Reviews

, Volume 94, Issue 1, pp 381–396

Cloud Formation and the Possible Significance of Charge for Atmospheric Condensation and Ice Nuclei

  • R. Giles Harrison

DOI: 10.1023/A:1026708415235

Cite this article as:
Harrison, R.G. Space Science Reviews (2000) 94: 381. doi:10.1023/A:1026708415235


Cloud formation in the atmosphere is related to the presence of water vapour, cloud condensation nuclei (CCN) and ice nuclei (IN). Ionisation in the atmosphere is caused by a variety of sources, but the contribution from cosmic rays is always present and is modulated by the solar cycle. Methods of investigating the variability in ionisation are described. The mechanisms proposed by which (1) ionisation could influence cloud formation, and (2) by which changes to the CCN and IN could occur are discussed. Direct formation of sulphate CN is conceivable in atmospheric air by radioactivity, and charging of molecular clusters leads to greater collisions rates than for neutral clusters. Modification of the ice nucleation efficiency of aerosol could also have atmospheric effects through latent heat release. However in both cases definitive atmospheric experimental work is lacking and therefore any link between solar variability and clouds remains unproven.

Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • R. Giles Harrison
    • 1
  1. 1.Department of MeteorologyThe University of ReadingReadingUK

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