Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Glycine in aerosol water droplets: a critical assessment of Kohler theory by predicting surface tension from molecular dynamics simulations
Stockholm University, Faculty of Science, Department of Meteorology .
Stockholm University, Faculty of Science, Department of Meteorology .
Show others and affiliations
2011 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 11, no 2, 519-527 p.Article in journal (Refereed) Published
Abstract [en]

Aerosol particles in the atmosphere are important participants in the formation of cloud droplets and have significant impact on cloud albedo and global climate. According to the Kohler theory which describes the nucleation and the equilibrium growth of cloud droplets, the surface tension of an aerosol droplet is one of the most important factors that determine the critical supersaturation of droplet activation. In this paper, with specific interest to remote marine aerosol, we predict the surface tension of aerosol droplets by performing molecular dynamics simulations on two model systems, the pure water droplets and glycine in water droplets. The curvature dependence of the surface tension is interpolated by a quadratic polynomial over the nano-sized droplets and the limiting case of a planar interface, so that the so-called Aitken mode particles which are critical for droplet formation could be covered and the Kohler equation could be improved by incorporating surface tension corrections.

Place, publisher, year, edition, pages
2011. Vol. 11, no 2, 519-527 p.
National Category
Meteorology and Atmospheric Sciences
Research subject
Atmospheric Sciences and Oceanography
Identifiers
URN: urn:nbn:se:su:diva-68674DOI: 10.5194/acp-11-519-2011ISI: 000286722300008OAI: oai:DiVA.org:su-68674DiVA: diva2:472951
Note

authorCount :5

Available from: 2012-01-04 Created: 2012-01-04 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Beyond Köhler theory: Molecular dynamics simulations as a tool for atmospheric science
Open this publication in new window or tab >>Beyond Köhler theory: Molecular dynamics simulations as a tool for atmospheric science
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, the results from molecular dynamics (MD) simulations of nanoaerosol clusters are discussed. The connecting link of these studies is the Köhler theory, which is the theory of condensational growth and activation of cloud droplets to form clouds. By investigating parameters such as the surface tension, state of mixture and morphology of nanoaerosol particles, conclusions can be drawn to improve the Köhler theory to include the effects of organic compounds previously unaccounted for.

For the terrestrial environment, the simulations show that the natural surfactant cis-pinonic acid, an oxidation product evaporated from boreal trees, spontaneously accumulates at the surface of nanoaerosol clusters and thereby reduces the surface tension. The surface tension depression is related to the concentration of the surfactant and the size of the clusters. Surface tension is an important parameter of the Köhler theory. A decrease of the surface tension can lower the critical water vapour supersaturation needed for cloud droplet activation, giving rise to more, but smaller cloud droplets (Twomey effect) which in turn could change the optical properties of the cloud. It was also shown that the three organic surfactants, being model compounds for so called Humic-like substances (HULIS) have the ability to form aggregates inside the nanoaerosol clusters. These HULIS aggregates can also promote the solubilization of hydrophobic organic carbon in the form of fluoranthene, enabling soot taking part in cloud drop formation.

Dissolved intermediately surface-active free amino acids were shown to be of some relevance for cloud formation over remote marine areas. The MD simulations showed differences between the interacting forces for spherical and planar interfaces of amino acids solutions.

This thesis has emphasized the surface-active properties of organic compounds, including model HULIS and amino acids and their effect on surface tension and molecular orientation including aggregate formation in nanoaerosol clusters and their activation to form droplets. This thesis shows that the Köhler equation does not fully satisfactory describe the condensational growth of nano-sized droplets containing organic surfactants. Different approaches are suggested as revisions of the Köhler theory.

Place, publisher, year, edition, pages
Stockholm: Department of Meteorology, Stockholm University, 2013. 64 p.
Keyword
Köhler theory, molecular dynamics, surface tension, aggregate, climate
National Category
Meteorology and Atmospheric Sciences
Research subject
Atmospheric Sciences and Oceanography
Identifiers
urn:nbn:se:su:diva-83208 (URN)978-91-7447-619-4 (ISBN)
Public defence
2013-02-08, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 5: Manuscript.

Available from: 2013-01-17 Created: 2012-12-05 Last updated: 2013-01-23Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Hede, ThomasLeck, Caroline
By organisation
Department of Meteorology
In the same journal
Atmospheric Chemistry And Physics
Meteorology and Atmospheric Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 52 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf