Dimensions and aspect ratios of natural ice crystals

Um, Junshik; McFarquhar, Greg M.; Hong, Yulan; Lee, Seoung Soo; Jung, Cheolkon; Lawson, R. Paul; Mo, Q.

doi:10.5194/acp-15-3933-2015

Cited by 75 publications

(78 citation statements)

References 75 publications

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“…[79][80][81] Phase transitions 82,83 for inorganic and organic materials can be investigated in situ in great detail and under very low temperatures. The IN-ESEM platform can also be applied to other research areas where well-controlled temperature or RH are required such as cryobiology.…”

Section: Discussionmentioning

confidence: 99%

Direct observation of ice nucleation events on individual atmospheric particles

Wang

Knopf

China

et al. 2016

Phys. Chem. Chem. Phys.

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The work presents microscopic observations of heterogeneous ice nucleation from experiments conducted inside an environmental scanning electron microscope. Observations of ice formation on kaolinite particles demonstrate that ice preferentially nucleates at the edges of the stacked platelets, rather than on the basal planes. This platform is applied for directly detecting and tracking ice nucleating particles in ambient aerosol samples and is complemented by micro-spectroscopic chemical imaging. This technique opens a path to new physical chemistry studies of ice formation in atmospheric science, cryobiology, and material science.www.rsc.org/pccp Heterogeneous ice nucleation is a physical chemistry process of critical relevance to a range of topics in the fundamental and applied sciences and technologies. Heterogeneous ice nucleation remains insufficiently understood, partially due to the lack of experimental methods capable of obtaining in situ microscopic details of ice formation over nucleating substrates or particles. We present microscopic observations of ice nucleation events on kaolinite particles at the nanoscale and demonstrate the capability of direct tracking and micro-spectroscopic characterization of individual ice nucleating particles (INPs) in an authentic atmospheric sample. This approach utilizes a custom-built ice nucleation cell, interfaced with an Environmental Scanning Electron Microscope (IN-ESEM platform) operated at temperatures and relative humidities relevant for heterogeneous ice nucleation. The IN-ESEM platform allows dynamic observations of individual ice formation events over particles in isobaric and isothermal experiments. Isothermal experiments on individual kaolinite particles demonstrate that ice crystals preferably nucleate at the edges of the stacked kaolinite platelets, rather than on their basal planes.These experimental observations of the location of ice nucleation provide direct information for further theoretical chemistry predictions of ice formation on kaolinite.

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Section: Discussionmentioning

confidence: 99%

Direct observation of ice nucleation events on individual atmospheric particles

Wang

Knopf

China

et al. 2016

Phys. Chem. Chem. Phys.

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“…In addition, distributions of crystal aspect ratios (Fu 2007;Um and McFarquhar 2007;Yang and Fu 2009) and knowledge of single-scattering properties (e.g., Takano and Liou 1989;Yang et al 2005) and ice crystal surface roughness (Yang et al 2003) are needed for quantifying the radiative impact. Although many prior studies have measured distributions of ice water content (IWC) (Schiller et al 2008;Luebke et al 2013;Heymsfield et al 2013;Krämer et al 2016), ice crystal sizes (Heymsfield and Platt 1984;McFarquhar and Heymsfield 1996Ivanova et al 2001;Boudala et al 2002;Field and Heymsfield 2003;McFarquhar et al 2007a;Field et al 2007), of crystal habits (Heymsfield and Miloshevich 1995;Korolev et al 1999;Gallagher et al 2005;Um and McFarquhar 2009), and of aspect ratios (Auer and Veal 1970;Hobbs et al 1974;Davis 1974;Mitchell and Arnott 1994;Baker and Lawson 2006;Um et al 2015) in different environmental conditions, there are few comprehensive studies that have identified the manner in which the nucleation mechanism or cirrus formation mechanism controls these ice crystal properties. A larger database where properties are examined as a function of meteorological or crystal formation mechanisms (e.g., Muhlbauer et al 2014;Jackson et al 2015;Krämer et al 2016) is still needed to understand how different growth processes and formation mechanisms control the microphysical and radiative properties.…”

Section: B Atmospheric Importance Of Cirrus Freezing Mechanismsmentioning

confidence: 99%

Cirrus Clouds

Heymsfield

Tricht

Lawson

et al. 2017

Meteorological Monographs

148

139

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The goal of this chapter is to synthesize information about what is now known about one of the three main types of clouds, cirrus, and to identify areas where more knowledge is needed. Cirrus clouds, composed of ice particles, form in the upper troposphere, where temperatures are generally below 2308C. Satellite observations show that the maximumoccurrence frequency of cirrus is near the tropics, with a large latitudinal movement seasonally. In situ measurements obtained over a wide range of cirrus types, formation mechanisms, temperatures, and geographical locations indicate that the ice water content and particle size generally decrease with decreasing temperature, whereas the ice particle concentration is nearly constant or increases slightly with decreasing temperature. High ice concentrations, sometimes observed in strong updrafts, result from homogeneous nucleation. The satellite-based and in situ measurements indicate that cirrus ice crystals typically differ from the simple, idealized geometry for smooth hexagonal shapes, indicating complexity and/or surface roughness. Their shapes significantly impact cirrus radiative properties and feedbacks to climate. Cirrus clouds, one of the most uncertain components of general circulation models (GCM), pose one of the greatest challenges in predicting the rate and geographical pattern of climate change. Improved measurements of the properties and size distributions and surface structure of small ice crystals (about 20 mm) and identifying the dominant ice nucleation process (heterogeneous versus homogeneous ice nucleation) under different cloud dynamical forcings will lead to a better representation of their properties in GCM and in modeling their current and future effects on climate.

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“…Table 1. Percentages of ice hexagonal columns and plates in cirrus normalized to the total number of regular shape ice crystals [18]. …”

Section: Obtaining Bspms Of Polydisperse Cirrus Calculated Theoreticamentioning

confidence: 99%

“…bar chart 1 is for experiment and curve 2 is for gamma distribution [14] An extended version of the database developed at IAO SB RAS contains BSPMs calculated for regular shape hexagonal plates and columns [17]. To form the matrices for polydisperse ensembles of ice crystals consisting of the particles of both forms with the parameters of distributions of the particles corresponding to real cirrus, the relation of their fraction from the results of [18] were used. In this work, aggregated data on experimental investigations of microstructure of cirrus obtained in the framework of the projects TWP-ICE (tropics, 2006), ISDAC (Arctic, 2008), and SPARTICUS (middle latitudes, 2010) are shown for ice plates, columns, and crystals of other shapes.…”

Section: Obtaining Bspms Of Polydisperse Cirrus Calculated Theoreticamentioning

confidence: 99%