scholarly journals Estimating Surface Attachment Kinetic and Growth Transition Influences on Vapor-Grown Ice Crystals

2020 ◽  
Vol 77 (7) ◽  
pp. 2393-2410
Author(s):  
Gwenore F. Pokrifka ◽  
Alfred M. Moyle ◽  
Lavender Elle Hanson ◽  
Jerry Y. Harrington
Keyword(s):  
Diffusion Chamber ◽  
Ice Crystals ◽  
Growth Theory ◽  
Growth Data ◽  
Surface Attachment ◽  
Mass Growth ◽  
Vapor Growth ◽  
Deposition Coefficient ◽  
Direct Use ◽  
Large Decline

AbstractThere are few measurements of the vapor growth of small ice crystals at temperatures below −30°C. Presented here are mass-growth measurements of heterogeneously and homogeneously frozen ice particles grown within an electrodynamic levitation diffusion chamber at temperatures between −44° and −30°C and supersaturations si between 3% and 29%. These growth data are analyzed with two methods devised to estimate the deposition coefficient α without the direct use of si. Measurements of si are typically uncertain, which has called past estimates of α into question. We find that the deposition coefficient ranges from 0.002 to unity and is scattered with temperature, as shown in prior measurements. The data collectively also show a relationship between α and si, with α rising (falling) with increasing si for homogeneously (heterogeneously) frozen ice. Analysis of the normalized mass growth rates reveals that heterogeneously frozen crystals grow near the maximum rate at low si, but show increasingly inhibited (low α) growth at high si. Additionally, 7 of the 17 homogeneously frozen crystals cannot be modeled with faceted growth theory or constant α. These cases require the growth mode to transition from efficient to inefficient in time, leading to a large decline in α. Such transitions may be, in part, responsible for the inconsistency in prior measurements of α.

Semi-Analytic Functions to Calculate the Deposition Coefficients for Ice Crystal Vapor Growth in Bin and Bulk Microphysical Models.

2021 ◽  
Author(s):  
Jerry Y. Harrington ◽  
G. Alexander Sokolowsky ◽  
Hugh Morrison
Keyword(s):  
Ice Crystals ◽  
Mixing Ratio ◽  
Ice Crystal ◽  
Surface Attachment ◽  
Vapor Growth ◽  
Diffusion Limited ◽  
Cloud Models ◽  
Variable Surface ◽  
Deposition Coefficient ◽  
Relative Errors

AbstractNumerical cloud models require estimates of the vapor growth rate for ice crystals. Current bulk and bin microphysical parameterizations generally assume that vapor growth is diffusion limited, though some parameterizations include the influence of surface attachment kinetics through a constant deposition coefficient. A parameterization for variable deposition coefficients is provided herein. The parameterization is an explicit function of the ambient ice supersaturation and temperature, and an implicit function of crystal dimensions and pressure. The parameterization is valid for variable surface types including growth by dislocations and growth by step nucleation. Deposition coefficients are predicted for the two primary growth directions of crystals, allowing for the evolution of the primary habits. Comparisons with benchmark calculations of instantaneous mass growth indicate that the parameterization is accurate to within a relative error of 1%. Parcel model simulations using Lagrangian microphysics as a benchmark indicate that the bulk parameterization captures the evolution of mass mixing ratio and fall speed with typical relative errors of less than 10%, whereas the average axis lengths can have errors of up to 20%. The bin model produces greater accuracy with relative errors often less that 10%. The deposition coefficient parameterization can be used in any bulk and bin scheme, with low error, if an equivalent volume spherical radius is provided.

scholarly journals Levitation Diffusion Chamber Measurements of the Mass Growth of Small Ice Crystals from Vapor

2016 ◽  
Vol 73 (7) ◽  
pp. 2743-2758 ◽  
Author(s):  
Alexander Harrison ◽  
Alfred M. Moyle ◽  
Marcus Hanson ◽  
Jerry Y. Harrington
Keyword(s):  
Ambient Pressure ◽  
Particle Growth ◽  
Diffusion Chamber ◽  
Copper Plate ◽  
Growth Data ◽  
Surface Kinetics ◽  
Shape Factors ◽  
Mass Growth ◽  
Ice Particles ◽  
Chamber Measurements

Abstract A levitation diffusion chamber designed to examine the mass growth from the vapor of small ice particles (diameter < 100 μm) at ambient pressure (≃970 hPa) and low temperature (T < −30°C) is presented. The diffusion chamber is unique in that charged ice particles are levitated by an opposing voltage on the lower copper plate with lateral stability provided by button quadrupole electrodes attached to the upper copper plate. The button electrodes are far from the ice particle growth region, allowing ice particles to grow free of substrate influences. Experiments have been conducted for temperatures from −30° to −35.7°C, ice supersaturations from 2.5% to 28.6%, and over growth times ranging from 5 to 15 min. The experiments indicate that mass varies nonlinearly in time and exhibits a dependence on initial particle radius and ice supersaturation in accord with expectations from theory. In contrast to expectations from spherical capacitance theory, the derived mass growth rates do not scale linearly with radius, and derived effective shape factors (capacitance normalized with radius) are approximately 0.5. Fitting the growth data with a theoretical model indicates that growth is limited by surface kinetics with deposition coefficients ranging from 0.003 to 0.02.

Thunderstorm-Precipitation Growth and Electrical-Charge Generation *

1953 ◽  
Vol 34 (3) ◽  
pp. 117-123 ◽  
Author(s):  
S. E. Reynolds
Keyword(s):  
Charge Separation ◽  
Cloud Droplet ◽  
Electrical Charge ◽  
Generation Mechanism ◽  
Ice Crystals ◽  
Droplet Growth ◽  
Growth Theory ◽  
Development Pattern ◽  
Growth Data ◽  
Charge Generation

It is shown, by use of Langmuir's precipitation growth data and Ludlam's hailstone heat economy data, that the glaze-ice thunderstorm charge generation mechanism suggested by E. J. Workman and the author is consistent with the thunderstorm cell development pattern observed by Workman and the author. The environment of charge separation is found theoretically. It also is shown that the initiation of precipitation in Midwestern thunderstorms without the involvement of ice crystals is consistent with Langmuir's cloud-droplet growth theory.

scholarly journals On Calculating Deposition Coefficients and Aspect-Ratio Evolution in Approximate Models of Ice Crystal Vapor Growth

2019 ◽  
Vol 76 (6) ◽  
pp. 1609-1625 ◽  
Author(s):  
Jerry Y. Harrington ◽  
Alfred Moyle ◽  
Lavender Elle Hanson ◽  
Hugh Morrison
Keyword(s):  
Aspect Ratio ◽  
Free Fall ◽  
Parametric Models ◽  
Ice Crystal ◽  
Growth Data ◽  
Surface Attachment ◽  
Vapor Growth ◽  
Liquid Saturation ◽  
Cloud Models ◽  
Small Crystals

Abstract Models of ice crystal vapor growth require estimates of the deposition coefficient α when surface attachment kinetics limit growth and when ice crystal shape is predicted. Parametric models can be used to calculate α for faceted growth as long as characteristic supersaturation values are known. However, previously published measurements of are limited to temperatures higher than −40°C. Estimates of at temperatures between −40° and −70°C are provided here through reanalysis of vapor growth data. The estimated follow the same functional temperature dependence as data taken at higher temperatures. Polynomial fits to are used as inputs to a parameterization of α suitable for use in cloud models. Comparisons of the parameterization with wind tunnel data show that growth at liquid saturation and constant temperatures between −3° and −20°C can be modeled by ledge nucleation for larger (hundreds of micrometers) crystals; however, comparisons with free-fall chamber data at −7°C suggest that dislocation growth may be required to model the vapor growth of small crystals (~20 μm) at liquid saturation. The comparisons with free-fall chamber data also show that the parameterization can reproduce the measured pressure dependence of aspect-ratio evolution. Comparisons with a hexagonal growth model indicate that aspect-ratio evolution based on the theory of Chen and Lamb produces unrealistically fast column growth near −7°C that is mitigated if a theory based on faceted growth is used. This result indicates that the growth hypothesis used in habit-evolving microphysical models needs to be revised when deposition coefficients are predicted.

scholarly journals A Parameterization of Sticking Efficiency for Collisions of Snow and Graupel with Ice Crystals: Theory and Comparison with Observations*

2015 ◽  
Vol 72 (12) ◽  
pp. 4885-4902 ◽  
Author(s):  
Vaughan T. J. Phillips ◽  
Marco Formenton ◽  
Aaron Bansemer ◽  
Innocent Kudzotsa ◽  
Barry Lienert
Keyword(s):  
Probability Distribution ◽  
Kinetic Energy ◽  
Ice Crystals ◽  
Field Observations ◽  
Laboratory Studies ◽  
Atmospheric Models ◽  
Vapor Growth ◽  
Collision Processes ◽  
Work Done ◽  
Temperature Surface

Abstract A new parameterization of sticking efficiency for aggregation of ice crystals onto snow and graupel is presented. This parameter plays a crucial role for the formation of ice precipitation and for electrification processes. The parameterization is intended to be used in atmospheric models simulating the aggregation of ice particles in glaciated clouds. It should improve the ability to forecast snow. Based on experimental results and general considerations of collision processes, dependencies of the sticking efficiency on temperature, surface area, and collision kinetic energy of impacting particles are derived. The parameters have been estimated from some laboratory observations by simulating the experiments and minimizing the squares of the errors of the prediction of observed quantities. The predictions from the new scheme are compared with other available laboratory and field observations. The comparisons show that the parameterization is able to reproduce the thermal behavior of sticking efficiency, observed in published laboratory studies, with a peak around −15°C corresponding to dendritic vapor growth of ice. Finally, a new theory of sticking efficiency is proposed. It explains the empirically derived parameterization in terms of a probability distribution of the work that would be required to separate two contacting particles colliding in all possible ways among many otherwise identical collisions of the same pair with a given initial collision kinetic energy. For each collision, if this work done would exceed the initial collision kinetic energy, then there is no separation after impact. The probability of that occurring equals the sticking efficiency.

scholarly journals Using depolarization to quantify ice nucleating particle concentrations: a new method

2017 ◽  
Vol 10 (12) ◽  
pp. 4639-4657 ◽  
Author(s):  
Jake Zenker ◽  
Kristen N. Collier ◽  
Guanglang Xu ◽  
Ping Yang ◽  
Ezra J. T. Levin ◽  
...  
Keyword(s):  
Standard Procedure ◽  
Diffusion Chamber ◽  
Operating Conditions ◽  
Ice Crystals ◽  
New Method ◽  
State University ◽  
Analysis Method ◽  
Colorado State University ◽  
Nominal Size ◽  
Wide Range

Abstract. We have developed a new method to determine ice nucleating particle (INP) concentrations observed by the Texas A&M University continuous flow diffusion chamber (CFDC) under a wide range of operating conditions. In this study, we evaluate differences in particle optical properties detected by the Cloud and Aerosol Spectrometer with POLarization (CASPOL) to differentiate between ice crystals, droplets, and aerosols. The depolarization signal from the CASPOL instrument is used to determine the occurrence of water droplet breakthrough (WDBT) conditions in the CFDC. The standard procedure for determining INP concentration is to count all particles that have grown beyond a nominal size cutoff as ice crystals. During WDBT this procedure overestimates INP concentration, because large droplets are miscounted as ice crystals. Here we design a new analysis method based on depolarization ratio that can extend the range of operating conditions of the CFDC. The method agrees reasonably well with the traditional method under non-WDBT conditions with a mean percent error of ±32.1 %. Additionally, a comparison with the Colorado State University CFDC shows that the new analysis method can be used reliably during WDBT conditions.

Modeling Ice Crystal Aspect Ratio Evolution during Riming: A Single-Particle Growth Model

2015 ◽  
Vol 72 (7) ◽  
pp. 2569-2590 ◽  
Author(s):  
Anders A. Jensen ◽  
Jerry Y. Harrington
Keyword(s):  
Wind Tunnel ◽  
Growth Model ◽  
Liquid Water ◽  
Single Particle ◽  
Liquid Drop ◽  
Ice Crystals ◽  
Ice Crystal ◽  
Vapor Growth ◽  
Wind Tunnel Data ◽  
Fall Speed

This paper describes and tests a single-particle ice growth model that evolves both ice crystal mass and shape as a result of vapor growth and riming. Columnar collision efficiencies in the model are calculated using a new theoretical method derived from spherical collision efficiencies. The model is able to evolve mass, shape, and fall speed of growing ice across a range of temperatures, and it compares well with wind tunnel data. The onset time of riming and the effects of riming on mass and fall speed between −3° and −16°C are modeled, as compared with wind tunnel data for a liquid water content of 0.4 g m−3. Under these conditions, riming is constrained to the more isometric habits near −10° and −4°C. It is shown that the mass and fall speed of riming dendrites depend on the liquid drop distribution properties, leading to a range of mass–size and fall speed–size relationships. Riming at low liquid water contents is shown to be sensitive to ice crystal habit and liquid drop size. Moreover, very light riming can affect the shape of ice crystals enough to reduce vapor growth and suppress overall mass growth, as compared with those same ice crystals if they were unrimed.

scholarly journals Mesoscopic surface roughness of ice crystals pervasive across a wide range of ice crystal conditions

2014 ◽  
Vol 14 (22) ◽  
pp. 12357-12371 ◽  
Author(s):  
N. B. Magee ◽  
A. Miller ◽  
M. Amaral ◽  
A. Cumiskey
Keyword(s):  
Surface Roughness ◽  
Environmental Scanning Electron Microscopy ◽  
Diffusion Chamber ◽  
Ice Crystals ◽  
Environmental Scanning ◽  
Ice Crystal ◽  
Hexagonal Ice ◽  
Wide Range ◽  
Ice Surfaces ◽  
Cloud Modeling

Abstract. Here we show high-magnification images of hexagonal ice crystals acquired by environmental scanning electron microscopy (ESEM). Most ice crystals were grown and sublimated in the water vapor environment of an FEI-Quanta-200 ESEM, but crystals grown in a laboratory diffusion chamber were also transferred intact and imaged via ESEM. All of these images display prominent mesoscopic topography including linear striations, ridges, islands, steps, peaks, pits, and crevasses; the roughness is not observed to be confined to prism facets. The observations represent the most highly magnified images of ice surfaces yet reported and expand the range of conditions in which rough surface features are known to be conspicuous. Microscale surface topography is seen to be ubiquitously present at temperatures ranging from −10 °C to −40 °C, in supersaturated and subsaturated conditions, on all crystal facets, and irrespective of substrate. Despite the constant presence of surface roughness, the patterns of roughness are observed to be dramatically different between growing and sublimating crystals, and transferred crystals also display qualitatively different patterns of roughness. Crystals are also demonstrated to sometimes exhibit inhibited growth in moderately supersaturated conditions following exposure to near-equilibrium conditions, a phenomenon interpreted as evidence of 2-D nucleation. New knowledge about the characteristics of these features could affect the fundamental understanding of ice surfaces and their physical parameterization in the context of satellite retrievals and cloud modeling. Links to supplemental videos of ice growth and sublimation are provided.

scholarly journals What controls the low ice number concentration in the upper troposphere?

2016 ◽  
Vol 16 (19) ◽  
pp. 12411-12424 ◽  
Author(s):  
Cheng Zhou ◽  
Joyce E. Penner ◽  
Guangxing Lin ◽  
Xiaohong Liu ◽  
Minghuai Wang
Keyword(s):  
Water Vapour ◽  
Large Scale ◽  
Vapour Deposition ◽  
Organic Aerosol ◽  
Ice Crystals ◽  
Tropical Tropopause ◽  
Deposition Coefficient ◽  
Cloud Ice ◽  
Homogeneous Freezing ◽  
Good Agreement

Abstract. Cirrus clouds in the tropical tropopause play a key role in regulating the moisture entering the stratosphere through their dehydrating effect. Low ice number concentrations ( <  200 L−1) and high supersaturations (150–160 %) have been observed in these clouds. Different mechanisms have been proposed to explain these low ice number concentrations, including the inhibition of homogeneous freezing by the deposition of water vapour onto pre-existing ice crystals, heterogeneous ice formation on glassy organic aerosol ice nuclei (IN), and limiting the formation of ice number from high-frequency gravity waves. In this study, we examined the effect from three different representations of updraft velocities, the effect from pre-existing ice crystals, the effect from different water vapour deposition coefficients (α  =  0.1 or 1), and the effect of 0.1 % of the total secondary organic aerosol (SOA) particles acting as IN. Model-simulated ice crystal numbers are compared against an aircraft observational dataset.Including the effect from water vapour deposition on pre-existing ice particles can effectively reduce simulated in-cloud ice number concentrations for all model setups. A larger water vapour deposition coefficient (α  =  1) can also efficiently reduce ice number concentrations at temperatures below 205 K, but less so at higher temperatures. SOA acting as IN is most effective at reducing ice number concentrations when the effective updraft velocities are moderate ( ∼  0.05–0.2 m s−1). However, the effects of including SOA as IN and using (α  =  1) are diminished when the effect from pre-existing ice is included.When a grid-resolved large-scale updraft velocity ( <  0.1 m s−1) is used, the ice nucleation parameterization with homogeneous freezing only or with both homogeneous freezing and heterogeneous nucleation is able to generate low ice number concentrations in good agreement with observations for temperatures below 205 K as long as the pre-existing ice effect is included. For the moderate updraft velocity ( ∼  0.05–0.2 m s−1), simulated ice number concentrations in good agreement with observations at temperatures below 205 K can be achieved if effects from pre-existing ice, a larger water vapour deposition coefficient (α  =  1), and SOA IN are all included. Using the sub-grid-scale turbulent kinetic energy (TKE)-based updraft velocity ( ∼  0–2 m s−1) always overestimates the ice number concentrations at temperatures below 205 K but compares well with observations at temperatures above 205 K when the pre-existing ice effect is included.

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