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Droplet nucleation and growth in orographic clouds in relation to the aerosol population

Martinsson, Bengt G. LU ; Frank, Göran LU ; Cederfelt, Sven Inge ; Swietlicki, Erik LU ; Berg, Olle H. ; Zhou, Jingchuan LU ; Bower, Keith N. ; Bradbury, Carl ; Birmili, Wolfram and Stratmann, Frank , et al. (1999) In Atmospheric Research 50(3-4). p.289-315
Abstract

The formation and development of orographic clouds was studied in a field experiment comprising several measurement sites at a mountain ridge. The influence of the aerosol population present on the cloud microstructure was studied in relation to the dynamics in the cloud formation. Droplet nucleation scavenging was investigated by the introduction of a non-dimensional particle diameter related to the process, and it was found that the scavenging rose rapidly in a relatively narrow particle size interval. The size dependency of the scavenging could partly be explained by external mixture of the aerosol. The large particles in the cloud interstitial aerosol was found to be of a chemical nature which allows for only a very weak uptake of... (More)

The formation and development of orographic clouds was studied in a field experiment comprising several measurement sites at a mountain ridge. The influence of the aerosol population present on the cloud microstructure was studied in relation to the dynamics in the cloud formation. Droplet nucleation scavenging was investigated by the introduction of a non-dimensional particle diameter related to the process, and it was found that the scavenging rose rapidly in a relatively narrow particle size interval. The size dependency of the scavenging could partly be explained by external mixture of the aerosol. The large particles in the cloud interstitial aerosol was found to be of a chemical nature which allows for only a very weak uptake of water, implying that the chemical composition of these particles rather than entrainment of dry air prevented the droplet nucleation. The aerosol particle number concentration was found to strongly influence the cloud microstructure. Droplet number concentrations up to approximately 2000 cm-3 were observed together with a substantially reduced effective droplet diameter. The observed effect of elevated particle number concentrations in orographic clouds was generalised to the climatologically more important stratiform clouds by the use of a cloud model. It was found that the microstructure of stratiform clouds was strongly dependent on the aerosol population present as well on the dynamics in the cloud formation.

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publication status
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subject
keywords
Aerosol, Climate, Cloud, Microphysics, Number concentration, Scavenging, Solute concentration
in
Atmospheric Research
volume
50
issue
3-4
pages
27 pages
publisher
Elsevier
external identifiers
  • scopus:6744227921
ISSN
0169-8095
DOI
10.1016/S0169-8095(98)00108-2
language
English
LU publication?
yes
id
0581d684-1fd3-4739-876d-65e75a4e602d
date added to LUP
2019-05-16 09:39:51
date last changed
2019-11-25 09:30:06
@article{0581d684-1fd3-4739-876d-65e75a4e602d,
  abstract     = {<p>The formation and development of orographic clouds was studied in a field experiment comprising several measurement sites at a mountain ridge. The influence of the aerosol population present on the cloud microstructure was studied in relation to the dynamics in the cloud formation. Droplet nucleation scavenging was investigated by the introduction of a non-dimensional particle diameter related to the process, and it was found that the scavenging rose rapidly in a relatively narrow particle size interval. The size dependency of the scavenging could partly be explained by external mixture of the aerosol. The large particles in the cloud interstitial aerosol was found to be of a chemical nature which allows for only a very weak uptake of water, implying that the chemical composition of these particles rather than entrainment of dry air prevented the droplet nucleation. The aerosol particle number concentration was found to strongly influence the cloud microstructure. Droplet number concentrations up to approximately 2000 cm<sup>-3</sup> were observed together with a substantially reduced effective droplet diameter. The observed effect of elevated particle number concentrations in orographic clouds was generalised to the climatologically more important stratiform clouds by the use of a cloud model. It was found that the microstructure of stratiform clouds was strongly dependent on the aerosol population present as well on the dynamics in the cloud formation.</p>},
  author       = {Martinsson, Bengt G. and Frank, Göran and Cederfelt, Sven Inge and Swietlicki, Erik and Berg, Olle H. and Zhou, Jingchuan and Bower, Keith N. and Bradbury, Carl and Birmili, Wolfram and Stratmann, Frank and Wendisch, Manfred and Wiedensohler, Alfred and Yuskiewicz, Brett A.},
  issn         = {0169-8095},
  language     = {eng},
  month        = {03},
  number       = {3-4},
  pages        = {289--315},
  publisher    = {Elsevier},
  series       = {Atmospheric Research},
  title        = {Droplet nucleation and growth in orographic clouds in relation to the aerosol population},
  url          = {http://dx.doi.org/10.1016/S0169-8095(98)00108-2},
  doi          = {10.1016/S0169-8095(98)00108-2},
  volume       = {50},
  year         = {1999},
}