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Cloud-droplet growt...
Cloud-droplet growth due to supersaturation fluctuations in stratiform clouds
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- Li, Xiang-Yung (författare)
- KTH,Nordic Institute for Theoretical Physics NORDITA
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- Svensson, Gunilla (författare)
- Stockholms universitet,Meteorologiska institutionen (MISU),Swedish e-Science Research Centre, Sweden; National Center for Atmospheric Research, USA
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- Brandenburg, Axel (författare)
- Stockholms universitet,KTH,Nordic Institute for Theoretical Physics NORDITA,Nordiska institutet för teoretisk fysik (Nordita),Institutionen för astronomi,University of Colorado, USA
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Haugen, N. E. L. (författare)
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- Li, Xiang-Yu (författare)
- Stockholms universitet,Meteorologiska institutionen (MISU),Nordiska institutet för teoretisk fysik (Nordita),Swedish e-Science Research Centre, Sweden; University of Colorado, USA
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(creator_code:org_t)
- 2019-01-17
- 2019
- Engelska.
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 19:1, s. 639-648
- Relaterad länk:
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https://acp.copernic...
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https://doi.org/10.5...
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https://urn.kb.se/re...
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https://doi.org/10.5...
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https://urn.kb.se/re...
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Abstract
Ämnesord
Stäng
- Condensational growth of cloud droplets due to supersaturation fluctuations is investigated by solving the hydrodynamic and thermodynamic equations using direct numerical simulations (DNS) with droplets being modeled as Lagrangian particles. The supersaturation field is calculated directly by simulating the temperature and water vapor fields instead of being treated as a passive scalar. Thermodynamic feedbacks to the fields due to condensation are also included for completeness. We find that the width of droplet size distributions increases with time, which is contrary to the classical theory without supersaturation fluctuations, where condensational growth leads to progressively narrower size distributions. Nevertheless, in agreement with earlier Lagrangian stochastic models of the condensational growth, the standard deviation of the surface area of droplets increases as t 1/2 . Also, for the first time, we explicitly demonstrate that the time evolution of the size distribution is sensitive to the Reynolds number, but insensitive to the mean energy dissipation rate. This is shown to be due to the fact that temperature fluctuations and water vapor mixing ratio fluctuations increase with increasing Reynolds number; therefore the resulting supersaturation fluctuations are enhanced with increasing Reynolds number. Our simulations may explain the broadening of the size distribution in stratiform clouds qualitatively, where the mean updraft velocity is almost zero.
Ämnesord
- NATURVETENSKAP -- Fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences (hsv//eng)
- NATURVETENSKAP -- Geovetenskap och miljövetenskap (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences (hsv//eng)
Nyckelord
- air temperature
- cloud droplet
- computer simulation
- hydrodynamics
- Reynolds number
- size distribution
- stratiform cloud
- supersaturation
- surface area
- thermodynamics
- water vapor
- atmosfärvetenskap och oceanografi
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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