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Limin Zhou
and
Brian A. Tinsley

drivers (current output from thunderstorms and other highly electrified clouds); and the distribution of ionosphere–surface column resistance (which depends on ion production from cosmic rays and other energetic particles from the space environment, as well as ionization losses on natural and anthropogenic aerosols). Effects of J z on cloud microphysics arise because J z generates space charge in conductivity gradients because of droplet concentration gradients as it passes through clouds, and the

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Arthur L. Rangno

1. Introduction and background It has been more than 40 years since Koenig (1963) reported on what became one of the greatest enigmas in the field of cloud physics when he described the glaciating behavior of cumulus clouds that were never colder than −10°C. Koenig wrote, “. . . the (slightly supercooled) clouds were observed to develop large concentrations of ice particles in comparatively short time (less than ten minutes).” Koenig’s findings, acquired against the backdrop of a large

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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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Dong L. Wu
,
Alyn Lambert
,
William G. Read
,
Patrick Eriksson
, and
Jie Gong

1. Introduction Cloud ice and occurrence frequency in the upper troposphere contribute significantly to Earth’s total radiation and energy budgets. However, current climate and weather models produce a wide spread of values for these variables, leading to large uncertainties in the predicted dynamics and precipitation at the surface (e.g., Waliser et al. 2009 ; Eliasson et al. 2011 ; Jiang et al. 2012 ). Improving cloud ice retrieval and modeling is imperative and can be achieved by reducing

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David M. Romps
and
Andrew M. Vogelmann

1. Introduction For a given patch of sky, the distribution of horizontal cloud sizes plays an important role in setting the total cloud cover (e.g., Koren et al. 2008 ), the cloud radiative forcing (e.g., Marshak and Davis 2005 ), convective entrainment rates (e.g., Stirling and Stratton 2012 ; Neggers 2015 ), and the likelihood of precipitation (e.g., Jiang et al. 2010 ). Despite the importance of the cloud size distribution, it is not often measured directly. Instead, during field

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Jinghua Chen
,
Xiaoqing Wu
,
Yan Yin
, and
Hui Xiao

subtropical high ( Zhang 2001 ). Affected by the monsoon circulation, more convective clouds and precipitation are trigged during the summer monsoon period, which can affect the local hydrological cycle and radiation budget ( Ding and Chan 2005 ; Ding et al. 2007 ; He et al. 2007 ). The monsoon circulation paves the way for the development and production of clouds and precipitation, which play key roles in controlling the daily weather and local climate. On the other hand, previous studies (e.g., Yanai

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J. G. DeVore
,
A. T. Stair
,
A. LePage
,
D. Rall
,
J. Atkinson
,
D. Villanucci
,
S. A. Rappaport
,
P. C. Joss
, and
R. A. McClatchey

1. Introduction An understanding of global, three-dimensional clouds, including particle phase and size distributions of cloud particles, is essential for understanding man-made radiative forcing in the atmosphere (see Forster et al. 2007 ). This paper describes a new ground-based instrument to provide such measurements for clouds with optical depths ranging from 0 to ∼10. A network of such sensors could be used to gain information on the global statistical properties of these optically thin

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Alexei Korolev
and
George A. Isaac

1. Introduction Water vapor inside clouds plays a crucial role in their life cycle and precipitation formation. The understanding of the relationships between the vapor pressure and microphysical characteristics of clouds is one of the key questions of theoretical and applied physics of clouds. Knowledge of the humidity inside clouds is important for mesoscale and climate models. The in-cloud water vapor pressure is commonly assumed to be saturated with respect to liquid water in liquid clouds

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Jennifer D. Small
and
Patrick Y. Chuang

1. Introduction The initiation of precipitation in warm clouds has yet to be adequately explained ( Illingworth 1988 ; Beard and Ochs 1993 ; Laird et al. 2000 ). Warm rain formation requires that over ∼10–30 min ( Beard and Ochs 1993 ; Johnson 1993 ), cloud drops formed by condensation (∼10–20 μ m in diameter) must grow to become raindrops ( Baker and Latham 1979 ; Rogers and Yau 1989 ) through collision–coalescence. It has been shown that if a few drops with diameters 55 μ m and greater

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Xiaoqin Jing
,
Bart Geerts
,
Katja Friedrich
, and
Binod Pokharel

1. Introduction In an effort to enhance precipitation, especially in arid regions, glaciogenic cloud seeding has been conducted since the 1940s (e.g., Smith 1949 ; Langmuir 1950 ; Vonnegut and Chessin 1971 ; Hobbs et al. 1981 ; Bruintjes 1999 ). Silver iodide (AgI) has been widely used in both ground-based and airborne seeding because it has a crystal structure that is similar to that of ice ( Vonnegut and Chessin 1971 ) and therefore AgI particles can act as ice nuclei at temperatures

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