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DOI	10.5194/acp-19-639-2019
	Cloud-droplet growth due to supersaturation fluctuations in stratiform clouds
	Li X.-Y.; Svensson G.; Brandenburg A.; Haugen N.E.L.
发表日期	2019
ISSN	16807316
起始页码	639
结束页码	648
卷号	19 期号:1
英文摘要	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. © 2019 Author(s).
语种	英语
scopus关键词	air temperature; cloud droplet; computer simulation; hydrodynamics; Reynolds number; size distribution; stratiform cloud; supersaturation; surface area; thermodynamics; water vapor
来源期刊	Atmospheric Chemistry and Physics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/144716
作者单位	Department of Meteorology, Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden; Nordita, KTH Royal Institute of Technology, Stockholm University, Stockholm, 10691, Sweden; Swedish e-Science Research Centre, Stockholm, Sweden; Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, United States; JILA, University of Colorado, Box 440, Boulder, CO 80303, United States; Global and Climate Dynamics, National Center for Atmospheric Research, Boulder, CO 80305, United States; Department of Astronomy, Stockholm University, Stockholm, 10691, Sweden; SINTEF Energy Research, Trondheim, 7465, Norway; Department of Energy and Process Engineering, NTNU, Trondheim, 7491, Norway
推荐引用方式 GB/T 7714	Li X.-Y.,Svensson G.,Brandenburg A.,et al. Cloud-droplet growth due to supersaturation fluctuations in stratiform clouds[J],2019,19(1).
APA	Li X.-Y.,Svensson G.,Brandenburg A.,&Haugen N.E.L..(2019).Cloud-droplet growth due to supersaturation fluctuations in stratiform clouds.Atmospheric Chemistry and Physics,19(1).
MLA	Li X.-Y.,et al."Cloud-droplet growth due to supersaturation fluctuations in stratiform clouds".Atmospheric Chemistry and Physics 19.1(2019).