Unusual Crystal in Ice Fog

Ohtake, Takeshi

doi:10.1175/1520-0469(1970)027<0509:uciif>2.0.co;2

Cited by 37 publications

(19 citation statements)

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“…This type of ice crystal is very rare in nature; photomicrographs of these crystals (see Fig. 2) were taken in Fairbanks, Alaska (Ohtake, 1970). This crystal type is subdivided into two categories: 14-face polyhedral ice crystal (G3a) and 20-face polyhedral ice crystal (G3b).…”

Section: Polyhedral-type Ice Crystal (G3)mentioning

confidence: 99%

A global classification of snow crystals, ice crystals, and solid precipitation based on observations from middle latitudes to polar regions

Kikuchi

Kameda

Higuchi

et al. 2013

Atmospheric Research

102

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Section: Polyhedral-type Ice Crystal (G3)mentioning

confidence: 99%

A global classification of snow crystals, ice crystals, and solid precipitation based on observations from middle latitudes to polar regions

Kikuchi

Kameda

Higuchi

et al. 2013

Atmospheric Research

102

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“…1. Ice particles with various habits: spheres, droxtals (Thuman and Robinson 1954;Ohtake 1970), aggregates, spatial bullet rosettes, hexagonal plates, hollow hexagonal columns, and solid hexagonal columns (Yang et al 2005). r area # r vol # r eff ,…”

Section: Definitionsmentioning

confidence: 99%

“…Contrail ice particles originating from freezing droplets first take a droxtal shape (Thuman and Robinson 1954;Ohtake 1970;Roth and Frohn 1998) and later may become more aspherical according to laboratory measurements (Gonda and Yamazaki 1984). The optical properties of droxtals are systematically different from those of spheres, in particular in the solar range, with less forward scattering (Yang et al 2003;Zhang et al 2004;Wendisch et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Effective Radius of Ice Particles in Cirrus and Contrails

Schumann

Mayer

Gierens

et al. 2011

Journal of the Atmospheric Sciences

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This paper discusses the ratio C between the volume mean radius and the effective radius of ice particles in cirrus and contrails. The volume mean radius is proportional to the third root of the ratio between ice water content and number of ice particles, and the effective radius measures the ratio between ice particle volume and projected cross-sectional area. For given ice water content and number concentration of ice particles, the optical depth scales linearly with C. Hence, C is an important input parameter for radiative forcing estimates. The ratio C in general depends strongly on the particle size distribution (PSD) and on the particle habits. For constant habits, C can be factored into a PSD and a habit factor. The PSD factor is generally less than one, while the habit factor is larger than one for convex or concave ice particles with random orientation. The value of C may get very small for power-law PSDs with exponent n between 24 and 0, which is often observed. For such PSDs, most of the particle volume is controlled by a few large particles, while most of the cross-sectional area is controlled by the many small particles. A new particle habit mix for contrail cirrus including small droxtal-shape particles is suggested. For measured cirrus and contrails, the dependence of C on volume mean particle radius, ambient humidity, and contrail age is determined. For cirrus, C varies typically between 0.4 and 1.1. In contrails, C 5 0.7 6 0.3, with uncertainty ranges increasing with the volume radius and contrail age. For the small particles in young contrails, the extinction efficiency in the solar range deviates considerably from the geometric optics limit.

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“…7), which may be multifaced "droxtals." As explained by Ohtake (1970), if crystals form from supercooled water droplets near Ϫ40°C, the droplets may freeze so quickly that the crystals do not have time to reach an equilibrium state for the development of normal hexagonal and rectangular faces. The result is a particle that appears to be quasi-spheroidal or potato shaped because the resolution of the image is not good enough to see the multiple facets.…”

Section: December 2006 B a K E R A N D L A W S O Nmentioning

confidence: 99%

In Situ Observations of the Microphysical Properties of Wave, Cirrus, and Anvil Clouds. Part I: Wave Clouds

Baker

Lawson

2006

J. Atmos. Sci.

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The microphysical properties of wave clouds based on data collected during 17 missions flown by a Learjet research aircraft are presented and discussed. This extensive dataset expands upon previous aircraft studies of wave clouds and introduces some new findings. While most aspects of the observations are consistent with basic cloud physics, some aspects remain difficult to interpret. Most notable among these are ice nucleation and aspects of the dynamical structure of wave clouds. A new hypothesis to explain the ice nucleation behavior is presented.The average and standard deviation of bulk microphysical parameters are presented for various locations within the wave clouds. Using digital imagery from a cloud particle imager (CPI), the shapes of ice particles are studied and crystal habits are classified. For certain categories-rosette shapes, columns, and irregular shapes-power-law parameterizations of particle area from particle length are presented. Polycrystals with rosette shapes dominate the ice mass while small spheroidal and irregularly shaped crystals dominate the ice number concentration.The concept and difficulties of using wave clouds as natural cloud physics laboratories are discussed and evaluated. A study of the riming threshold size of columns is in good agreement with the results of previous studies, showing that column width is the predominate factor in determining riming threshold. The first reported studies of the riming threshold size of rosette shapes and the threshold size for side-plane growth are presented.

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Unusual Crystal in Ice Fog

Cited by 37 publications

References 0 publications

A global classification of snow crystals, ice crystals, and solid precipitation based on observations from middle latitudes to polar regions

A global classification of snow crystals, ice crystals, and solid precipitation based on observations from middle latitudes to polar regions

Effective Radius of Ice Particles in Cirrus and Contrails

In Situ Observations of the Microphysical Properties of Wave, Cirrus, and Anvil Clouds. Part I: Wave Clouds

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