Boundary-Layer Meteorology

, Volume 41, Issue 1–4, pp 335–348 | Cite as

Pollution and cloud reflectance

  • S. Twomey
  • R. Gall
  • M. Leuthold
Part 4 Microphysics And Chemistry Related To Air Pollution


Conventional power plants are prolific sources of cloudnucleating particles. Consequently clouds forming in air influenced by such emissions contain higher concentrations of cloud droplets than would prevail in clean conditions; optical properties of clouds are thereby modified, causing them to reflect more sunlight and transmit less. That has obvious consequences for climate physics, but it may also be relevant for mesoscale processes since quite substantial energy changes are involved. Ships constitute isolated sources in an environment that is often quite clean, and when low thin cloud layers are present, ships delineate their courses in satellite images by bright lines. These lines are caused by the above-mentioned increase in reflectance, providing, on a scale of tens to hundreds of kilometers, a realization of an effect which on a climatic scale cannot be directly observed (but which is likely to be comparable in magnitude to the CO2 effect, but oppositely directed).


Optical Property Power Plant Satellite Image Energy Change Obvious Consequence 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© D. Reidel Publishing Company 1987

Authors and Affiliations

  • S. Twomey
    • 1
  • R. Gall
    • 1
  • M. Leuthold
    • 1
  1. 1.Institute of Atmospheric Physics University of ArizonaTucsonUnited States of America

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