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Steven K. Krueger, Hugh Morrison, and Ann M. Fridlind

with eight independent models and also across a range of numerical resolutions. The LES results for the subcloud layer were consistent with well-established convective boundary layer scalings. Direct validation of the cloud-layer results was difficult, although the tendency of the models to have cloud cover decreasing with time is at least broadly consistent with the observations. In the cloud layer, many of the results previously found in oversea cases are still applicable. For example, cloud

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Greg M. McFarquhar, Darrel Baumgardner, Aaron Bansemer, Steven J. Abel, Jonathan Crosier, Jeff French, Phil Rosenberg, Alexei Korolev, Alfons Schwarzoenboeck, Delphine Leroy, Junshik Um, Wei Wu, Andrew J. Heymsfield, Cynthia Twohy, Andrew Detwiler, Paul Field, Andrea Neumann, Richard Cotton, Duncan Axisa, and Jiayin Dong

1. Introduction Ice clouds cover ~30% of Earth ( Wylie et al. 2005 ; Stubenrauch et al. 2006 ) and make substantial contributions to radiative heating in the troposphere ( Ramaswamy and Ramanathan 1989 ). To represent cloud feedbacks in climate models, the effect of ice clouds on longwave and shortwave radiation must be quantified (e.g., Ardanuy et al. 1991 ). Ice microphysical processes also affect the evolution of weather phenomena through impacts on latent heating, which in turn drives the

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Sonia M. Kreidenweis, Markus Petters, and Ulrike Lohmann

theory of self-preserving size distributions, arriving at a dimensionally estimated slope for the large particle size range close to that proposed by Junge. Clark and Whitby (1967) tested the proposed relationships against experimental data for ambient aerosols collected using a continuous-flow system, comprising an electrical particle counter, a condensation nuclei counter, and an optical counter to cover the complete size range from ~2 nm to 6 μ m in diameter. They confirmed the Junge power

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Sue Ellen Haupt, Robert M. Rauber, Bruce Carmichael, Jason C. Knievel, and James L. Cogan

reviews only the history of deliberate attempts, based on underlying scientific hypotheses, to alter natural processes occurring in storms to produce additional precipitation or to reduce weather hazards. Inadvertent weather modification that, for example, might manifest as a reduction of air quality associated with human production of aerosol or as a change in climate due to accumulation of greenhouse gases associated with the burning of fossil fuels, is covered in other articles within this

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Graham Feingold and Allison McComiskey

resulting from an increase in aerosol reduces snow riming rates ( Borys et al. 2003 ) and ice loss through precipitation (the riming effect). On the other hand, an increase in the aerosol might result in an increase in ice nuclei (IN), more efficient precipitation, lower cloud cover, and more solar absorption (the glaciation effect; Lohmann 2002 ). Finally, in deep convective clouds, there is evidence of an association between the aerosol and cloud-top height, updraft velocity, and lightning activity

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M. Haeffelin, S. Crewell, A. J. Illingworth, G. Pappalardo, H. Russchenberg, M. Chiriaco, K. Ebell, R. J. Hogan, and F. Madonna

scales. The limitation of an atmospheric profiling observatory is that it can only document one location of the globe with its specific atmospheric properties. The aerosol distributions, meteorological anomalies, and cloud properties observed at that location are representative of a limited spatial domain. Hence, atmospheric profiling observatories are needed at many locations around the globe to cover climatically diverse areas: near coasts, in continental plains, mountains, and urban environments

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Ronald B. Smith

-10) Z F = − T S / γ . If γ = dT / dz = −6.5°C km −1 and surface temperature T S = 20°C, the melting level will be at Z F = (20/6.5) = 3.1 km. Above this level, precipitation will fall as snow. Below Z F , precipitation will fall as rain. This snow/rain boundary is often evident in mountain scenery ( Fig. 20-2 ). Because it depends so sensitively on surface temperature, Z F varies greatly with latitude, season, and weather type. In cold Arctic climates (e.g., Denali, Alaska) in winter

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Ulrich Schumann and Andrew J. Heymsfield

RH (for liquid saturation) and a parameter G , with saturation pressure p sat ( T ) over liquid water. From these equations, T LM ( G ) and T LC ( G , RH) can be determined by Newton iteration or from approximate solutions ( Schumann 2012 ). The parameter G covers the dependency of the threshold on ambient pressure p , and EI H2O , Q , and η , defined above, and the specific heat capacity c p of air, and molar masses M H2O and M air of water and air. This Schmidt–Appleman criterion

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Andrew J. Heymsfield, Martina Krämer, Anna Luebke, Phil Brown, Daniel J. Cziczo, Charmaine Franklin, Paul Lawson, Ulrike Lohmann, Greg McFarquhar, Zbigniew Ulanowski, and Kristof Van Tricht

/ CALIPSO data collected ( Fig. 2-2 ), with a significant proportion of this cirrus cloud cover in the tropical and subtropical zonal belts (56% of the total cirrus coverage occurs within ±30° latitude of the equator). Moreover, cirrus display a strong nocturnal frequency increase, in particular over land, of up to ~30% ( Wylie et al. 1994 ; Sassen et al. 2009 ; see Fig. 2-3 ). Cirrus detections by CloudSat / CALIPSO further reveal the relatively high altitude of occurrence ( Fig. 2-4 ), as

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Margaret A. LeMone, Wayne M. Angevine, Christopher S. Bretherton, Fei Chen, Jimy Dudhia, Evgeni Fedorovich, Kristina B. Katsaros, Donald H. Lenschow, Larry Mahrt, Edward G. Patton, Jielun Sun, Michael Tjernström, and Jeffrey Weil

insights provided through the direct numerical simulation (DNS) of Sullivan and McWilliams (2002) , observations and wave-tank experiments by Plant (1982) , and observations by Smith et al. (1992) and Grachev and Fairall (2001) , Kelly et al. (2009) modified the Hatlee–Wyngaard SGS scheme to include wave effects to replicate OHATS results. Conducted over a snow field, the Sno-HATS (2006) field study ( Bou-Zeid et al. 2010 ) provided additional data to buttress some of the HATS results in stable

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