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Jiming Sun, Parisa A. Ariya, Henry G. Leighton, and Man Kong Yau

1. Introduction Ice formation in both deep and shallow cumulus clouds impacts the atmospheric circulation through its impact on precipitation, on diabatic heating, and on the earth’s radiation budget because of the differences of the optical properties of water and ice particles. Although shallow cumulus clouds are widespread in the tropics and subtropics ( Rangno and Hobbs 2005 ; Masunaga and Kummerow 2006 ; Warren et al. 2007 ), the ice formation mechanism in warm-based precipitating

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Huiwen Xue, Graham Feingold, and Bjorn Stevens

the idea that precipitation may play a role in regulating boundary layer circulations and hence patterns of cloudiness and cloud amount. In this paper we continue a line of investigation that uses large-eddy simulation to help us understand some of the ways in which precipitation effects the organization and structure of trade wind cumuli. We focus on a case of cumulus beneath stratocumulus, loosely based on data collected during the Atlantic Trade Wind Experiment (ATEX), and thus combine some

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M. Pinsky and A. Khain

1. Introduction The main cloud parameters determining the effects of clouds on the radiative and energetic budget of Earth’s atmosphere are cloud cover, vertical profiles of liquid water content (LWC), droplet concentration, and the effective radius, which is directly related to the mean volume droplet radius. In large-scale models, small nonprecipitating cumulus clouds (Cu) are unresolvable and values of these parameters are calculated using simple parameterizations or are prescribed a priori

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Thijs Heus and Harm J. J. Jonker

1. Introduction The properties of shallow cumulus clouds have long been a much-studied topic in the research of atmospheric boundary layers. One important ongoing issue is the interaction between cloud and environment, despite the fact that it has been an open topic for more than half a century. Stommel (1947) based his cloud model on the concept of a lateral entraining plume, but Squires (1958) argued that cloud-top mixing and resulting penetrative downdrafts were better able to predict

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Yefim Kogan

by Khairoutdinov and Kogan (2000 , hereafter KK2000 ) for development of a microphysics parameterization for marine boundary layer (BL) stratocumulus clouds (often referred to as KK parameterization). Our goal is to expand the KK parameterization to represent shallow trade wind cumulus clouds. These clouds are dynamically more vigorous and exhibit a much broader range of cloud properties, relative to marine stratocumulus. Because of their prevalence over much of the subtropical and tropical

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Yonggang Wang, Bart Geerts, and Jeffrey French

1. Introduction Cumulus clouds are important in the earth system as they affect the vertical structure of tropospheric radiative heat flux divergence and dynamically couple the planetary boundary layer to the free troposphere through the vertical transport of heat, moisture, aerosol, and momentum (e.g., Siebesma et al. 2003 ). Cumulus cloud circulations are smaller than resolvable scales in numerical weather prediction (NWP) and general circulation models (e.g., Khairoutdinov et al. 2008

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George C. Craig and Andreas Dörnbrack

. 2004 ). Although they are sometimes referred to as “cloud resolving,” numerical models with a 1-km grid size clearly do not have sufficient resolution to accurately represent the complex turbulent flow that makes up a cumulus cloud. But what spacing is necessary to accurately simulate the transport, entrainment, and detrainment processes in such clouds? The properties of the moist turbulence in cumulus clouds are only partially understood, particularly at the cloud boundary where there is

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Samuel N. Stechmann and Bjorn Stevens

1. Introduction Cumulus clouds involve physical processes on a vast range of scales, all of which are important for a cloud’s development. These include aerosols and cloud droplets on scales smaller than 10 −3 m, turbulent motions on scales of roughly 1 m within the cloud, updrafts on scales of roughly 10 3 m, and the ambient environment in which the cloud forms. Because of this wide range of scales, clouds remain poorly understood and thus contribute greatly to uncertainty in predictions of

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Till M. Wagner and Hans-F. Graf

processes associated with convective clouds is of great importance for many other physical processes in an atmospheric general circulation model (AGCM). Convection controls to a large degree the vertical transport of moisture, chemical tracers, energy, and momentum. When precipitation forms in convective clouds, the net latent heat release directly couples convection to the large-scale dynamics. Cumulus convection not only takes part directly in the global energy and water cycle (transport), but also

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Dick Abma, Thijs Heus, and Juan Pedro Mellado

1. Introduction In parameterizations of (shallow) cumulus convection, the representation of mixing between cloud and environment plays a key role, usually in the form of entrainment and detrainment coefficients (e.g., Tiedtke 1989 ; Kain and Fritsch 1990 ; Neggers et al. 2009 ). Many currently operational parameterizations have a bulk approach, where the effects of the entire cloud field are accounted for by a few effective equations for the transport of heat and moisture. However, as

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