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DOI | 10.1175/JAS-D-19-0018.1 |
Dynamics of Subsiding Shells in Actively Growing Clouds with Vertical Updrafts | |
Nair, Vishnu1; Heus, Thijs2; van Reeuwijk, Maarten1 | |
2020-04-01 | |
发表期刊 | JOURNAL OF THE ATMOSPHERIC SCIENCES |
ISSN | 0022-4928 |
EISSN | 1520-0469 |
出版年 | 2020 |
卷号 | 77期号:4页码:1353-1369 |
文章类型 | Article |
语种 | 英语 |
国家 | England; USA |
英文摘要 | The dynamics of a subsiding shell at the edges of actively growing shallow cumulus clouds with updrafts is analyzed using direct numerical simulation. The actively growing clouds have a fixed in-cloud buoyancy and velocity. Turbulent mixing and evaporative cooling at the cloud edges generate a subsiding shell that grows with time. A self-similar regime is observed for first- and second-order moments when normalized with respective maximum values. Internal scales derived from integral properties of the flow problem are identified. A self-similarity analysis using these scales reveals that contrary to classical self-similar flows, the turbulent kinetic energy budget terms and velocity moments scale according to the buoyancy and not with the mean velocity. The shell thickness is observed to increase linearly with time. The buoyancy scale remains time invariant and is set by the initial cloud-environment thermodynamics. The shell accelerates ballistically with a magnitude set by the saturation value of the buoyancy of the cloud-environment mixture. In this regime, the shell is buoyancy driven and independent of the in-cloud velocity. Relations are obtained for predicting the shell thickness and minimum velocities by linking the internal scales with external flow parameters. The values thus calculated are consistent with the thickness and velocities observed in typical shallow cumulus clouds. The entrainment coefficient is a function of the initial state of the cloud and the environment, and is shown to be on the same order of magnitude as fractional entrainment rates calculated for large-scale models. |
英文关键词 | Convection Entrainment Turbulence Cumulus clouds |
领域 | 地球科学 |
收录类别 | SCI-E |
WOS记录号 | WOS:000528754800007 |
WOS关键词 | SHALLOW CUMULUS CLOUDS ; MASS FLUX ; ENTRAINMENT ; SIMULATION ; BOUNDARY ; MODELS |
WOS类目 | Meteorology & Atmospheric Sciences |
WOS研究方向 | Meteorology & Atmospheric Sciences |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/280320 |
专题 | 地球科学 |
作者单位 | 1.Imperial Coll London, Dept Civil & Environm Engn, London, England; 2.Cleveland State Univ, Dept Phys, Cleveland, OH 44115 USA |
推荐引用方式 GB/T 7714 | Nair, Vishnu,Heus, Thijs,van Reeuwijk, Maarten. Dynamics of Subsiding Shells in Actively Growing Clouds with Vertical Updrafts[J]. JOURNAL OF THE ATMOSPHERIC SCIENCES,2020,77(4):1353-1369. |
APA | Nair, Vishnu,Heus, Thijs,&van Reeuwijk, Maarten.(2020).Dynamics of Subsiding Shells in Actively Growing Clouds with Vertical Updrafts.JOURNAL OF THE ATMOSPHERIC SCIENCES,77(4),1353-1369. |
MLA | Nair, Vishnu,et al."Dynamics of Subsiding Shells in Actively Growing Clouds with Vertical Updrafts".JOURNAL OF THE ATMOSPHERIC SCIENCES 77.4(2020):1353-1369. |
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