To see the other types of publications on this topic, follow the link: Ice crystals.
Journal articles on the topic 'Ice crystals'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Ice crystals.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Furukawa, Yoshinori. "Ice Crystals." Crystals 9, no. 10 (2019): 540. http://dx.doi.org/10.3390/cryst9100540.
Full textAbstract:
The special issue on “Ice Crystals” includes seven contributed papers, which give the wide varieties of topics related to ice crystals. They focus on the interface structure of ice, the physical properties of hydrate crystals and the freezing properties of water controlled by antifreeze proteins. The present issue can be considered as a status report reviewing the research that has been made recently on ice crystals. These papers provide research information about the recent development of ice crystal research to readers.
2
Svensson, Anders, Karen G. Schmidt, Dorthe Dahl-Jensen, et al. "Properties of ice crystals in NorthGRIP late- to middle-Holocene ice." Annals of Glaciology 37 (2003): 113–18. http://dx.doi.org/10.3189/172756403781815636.
Full textAbstract:
AbstractDetailed measurements of crystal outlines and fabrics have been performed on 35 000 crystals in fifteen 10 × 20 cm2 vertical thin sections from the North Greenland Icecore Project (NorthGRIP) ice core, evenly distributed in the depth interval 115–880m. The crystals exhibit important changes over this period. As the ice gets older the mean crystal area increases towards a constant value, the shape of the crystals becomes increasingly irregular, and the area distribution of crystals develops from a single log-normal distribution into a bimodal lognormal distribution. The c-axis fabric of the ice shows a smooth development of an increasingly stronger vertical fabric with depth, and the formation of a weak vertical girdle. Already in the younger samples the fabric is rather strongly oriented towards vertical. The fabric and the area of individual crystals are found not to correlate. A simple model, which takes into account the vertical strain of the ice, is applied in an attempt to determine the crystal growth rate at NorthGRIP.
3
Zheng, Ouyang, Li Zhang, Qinxiu Sun, and Shucheng Liu. "Basic Theory of Ice Crystallization Based on Water Molecular Structure and Ice Structure." Foods 13, no. 17 (2024): 2773. http://dx.doi.org/10.3390/foods13172773.
Full textAbstract:
Freezing storage is the most common method of food preservation and the formation of ice crystals during freezing has an important impact on food quality. The water molecular structure, mechanism of ice crystal formation, and ice crystal structure are elaborated in the present review. Meanwhile the methods of ice crystal characterization are outlined. It is concluded that the distribution of the water molecule cluster structure during the crystallization process directly affects the formed ice crystals’ structure, but the intrinsic relationship needs to be further investigated. The morphology and distribution of ice crystals can be observed by experimental methods while simulation methods provide the possibility to study the molecular structure changes in water and ice crystals. It is hoped that this review will provide more information about ice crystallization and promote the control of ice crystals in frozen foods.
4
Murray, Benjamin J., Christoph G. Salzmann, Andrew J. Heymsfield, Steven Dobbie, Ryan R. Neely, and Christopher J. Cox. "Trigonal Ice Crystals in Earth’s Atmosphere." Bulletin of the American Meteorological Society 96, no. 9 (2015): 1519–31. http://dx.doi.org/10.1175/bams-d-13-00128.1.
Full textAbstract:
Abstract We are all familiar with the hexagonal shape of snow and ice crystals, and it is well established that their sixfold symmetry is derived from the arrangement of water molecules in a hexagonal crystal structure. However, atmospheric ice crystals with only threefold rotational symmetry are often observed, which is inconsistent with the hexagonal crystal structure of ordinary ice. These crystals are found in a wide range of different cloud types ranging from upper-tropospheric cirrus to contrails and diamond dust and they form at temperatures ranging from about −84° to −5°C. Recent experimental studies of ice crystal structures have shown that ice under a wide range of atmospheric conditions does not always conform to the standard hexagonal crystal structure. Instead, sequences of the hexagonal structure can be interlaced with cubic sequences to create stacking-disordered ice. This degrades the symmetry of the crystal structure so that, instead of having a hexagonal structure, they have a trigonal structure with a corresponding threefold symmetry. Hence, this implies that atmospheric ice crystals with threefold symmetry are made of stacking-disordered ice. We conclude that the presence of trigonal crystals in the atmosphere is consistent with rare Parry arc halos and also show that they have distinct radiative properties compared with hexagonal ice.
5
ZHANG, Lifen, Jianhui ZHAO, Bangtuo YU, Yaguo LYU, and Zhenxia LIU. "Numerical study of ice crystal movement and melting in rotating blade channels." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 42, no. 6 (2024): 987–95. https://doi.org/10.1051/jnwpu/20244260987.
Full textAbstract:
The motion and melting characteristics of ice crystals in the rotating blade channel are investigated. Firstly, the method of calculating local collection coefficient is proposed for rotating parts. Secondly, the numerical simulation of ice crystal movement and melting in the rotating blade channel is carried out to analyze the influence of ice crystal geometry parameters and working condition changes on the ice crystal impact location and ice crystal melting rate. The results show: ① the collection coefficient of ice crystal at the leading edge of the blade is the highest, the trailing edge of the pressure surface is also the area where the ice crystal may impact, while the root of the blade is less affected by centrifugal force; ② the larger the ice crystal content, the larger the collection rate of ice crystal at the same position on the blade surface; the larger the ice crystal diameter, the larger the collection rate of ice crystal at the suction surface, the smaller the collection rate of ice crystal at the pressure surface; the higher the non-spherical degree of ice crystal, the more likely the ice crystal will impact on the pressure surface; the higher the non-sphericity of ice crystals, the easier it is for the ice crystals to impact on the pressure surface; when the rotational speed decreases, the ice crystals are more likely to impact on the suction surface, and the impact area is also larger and closer to the blade root; ③ The melting ice crystals impacting on the pressure surface are more widely distributed, and the pressure surface is more prone to ice crystal adhesion and freezing than the suction surface; while, there are also melted ice crystals on the suction surface near the trailing edge, where ice crystals may also adhere; the larger the ice crystal content, the larger the diameter, the larger the non-sphericity, and when the rotational speed increases, the melting rate of ice crystals decreases.
6
K Schmidt, Karen Guldbæ, and Dorthe Dahl-Jensen. "An ice crystal model for Jupiter’s moon Europa." Annals of Glaciology 37 (2003): 129–33. http://dx.doi.org/10.3189/172756403781815735.
Full textAbstract:
AbstractA simple model for crystal growth in the ice shell of Europa has been made in order to estimate the size of ice crystals at Europa’s surface. If mass is lost from the surface of Europa due to sputtering processes, and the ice thickness is constant in time, ice crystals will be transported upwards in the ice shell. The crystals will therefore grow under varying conditions through the shell. The model predicts that ice crystals are 4 cm– 80 m across at the surface. For the preferred parameter values, a crystal size of the order of 7 m is calculated.
7
Sheridan, Lindsay M., Jerry Y. Harrington, Dennis Lamb, and Kara Sulia. "Influence of Ice Crystal Aspect Ratio on the Evolution of Ice Size Spectra during Vapor Depositional Growth." Journal of the Atmospheric Sciences 66, no. 12 (2009): 3732–43. http://dx.doi.org/10.1175/2009jas3113.1.
Full textAbstract:
Abstract The relationship among aspect ratio, initial size, and the evolution of the size spectrum is explored for ice crystals growing by vapor deposition. Ice crystal evolution is modeled based on the growth of spheroids, and the ice size spectrum is predicted using a model that is Lagrangian in crystal size and aspect ratio. A dependence of crystal aspect ratio on initial size is discerned: more exaggerated shapes are shown to result when the initial crystals are small, whereas more isometric shapes are found to result from initially large crystals. This result is due to the nature of the vapor gradients in the vicinity of the crystal surface. The more rapid growth of the smaller crystals is shown to produce a period during which the size distribution narrows, followed by a broadening led by the initially smallest crystals. The degree of broadening is shown to depend strongly on the primary habit and hence temperature.
8
Adams, Edward E., and Daniel A. Miller. "Ice crystals grown from vapor onto an orientated substrate: application to snow depth-hoar development and gas inclusions in lake ice." Journal of Glaciology 49, no. 164 (2003): 8–12. http://dx.doi.org/10.3189/172756503781830953.
Full textAbstract:
AbstractA laboratory experiment was conducted in which new ice crystals were nucleated from the vapor phase onto large existing ice crystals obtained from Antarctic lake ice. Flat, smooth ice-crystal surfaces were prepared, with c axes oriented either vertically or horizontally. When these were subjected to a supersaturated vapor environment, multiple individual crystals nucleated onto the substrates adopting the same crystallographic orientation as the parent. A dominant grain-growth scenario for kinetic-growth metamorphism in snow, which in some ways is analogous to the oriented morphologies in lake ice, is hypothesized. In the lake-ice-growth scenario, optimally oriented crystals will grow at the expense of those less preferentially positioned.The proposed dominant grain-growth theory for snow is in agreement with the observed decrease in the number of grains and the proximal similarity of crystal habit in kinetic-growth metamorphism in snow. Similarly, kinetic crystal growth on the interior of gas inclusions in Antarctic lake ice will also acquire the crystallographic orientation of the substrate ice. These small-faceted interior crystals significantly influence light scattering and penetration in the lake-ice cover.
9
Mo, Jingyi, Robert D. Groot, Graham McCartney, et al. "Ice Crystal Coarsening in Ice Cream during Cooling: A Comparison of Theory and Experiment." Crystals 9, no. 6 (2019): 321. http://dx.doi.org/10.3390/cryst9060321.
Full textAbstract:
Ice cream is a complex multi-phase structure and its perceived quality is closely related to the small size of ice crystals in the product. Understanding the quantitative coarsening behaviour of ice crystals will help manufacturers optimise ice cream formulations and processing. Using synchrotron X-ray tomography, we measured the time-dependent coarsening (Ostwald ripening) of ice crystals in ice cream during cooling at 0.05 °C/min. The results show ice crystal coarsening is highly temperature dependent, being rapid from ca. −6 to −12 °C but significantly slower at lower temperatures. We developed a numerical model, based on established coarsening theory, to calculate the relationship between crystal diameter, cooling rate and the weight fraction of sucrose in solution. The ice crystal diameters predicted by the model are found to agree well with the measured values if matrix diffusion is assumed to be slowed by a factor of 1.2 due to the presence of stabilizers or high molecular weight sugars in the ice cream formulation.
10
New, William H. "Ice Crystals." Journal of Modern Literature 23, no. 3 (2000): 565–73. http://dx.doi.org/10.1353/jml.2000.0013.
Full text
11
Koch, Inka, Sean Fitzsimons, Denis Samyn, and Jean-Louis Tison. "Marine ice recycling at the southern McMurdo Ice Shelf, Antarctica." Journal of Glaciology 61, no. 228 (2015): 689–701. http://dx.doi.org/10.3189/2015jog14j095.
Full textAbstract:
AbstractMarine ice accretes at the base of ice shelves, often infilling open structural weaknesses and increasing ice-shelf stability. However, the timing and location of marine ice formation remain poorly understood. This study determines marine ice source water composition and origin by examining marine ice crystal morphology, water isotope and solute chemistry in ice samples collected from the southern McMurdo Ice Shelf (SMIS), Antarctica. The measured co-isotopic record together with the output of a freezing model for frazil crystals indicate a spatio-temporally varying water source of sea water and relatively fresher water, such as melted meteoric or marine ice. This is in agreement with the occurrence of primarily banded and granular ice crystal facies typical for frazil ice crystals that nucleate in a supercooled mixture of water masses. We propose that marine ice exposed at the surface of SMIS, which experiences summer melt, is routed to the ice-shelf base via the tide crack. Here frazil crystals nucleate in a double diffusion mechanism of heat and salt between two water masses at their salinity-dependent freezing point. Recycling of previously formed marine ice facilitates ice-shelf self-sustenance in a warming climate.
12
Hirose, Koichiro, Koji Fukudome, Hiroya Mamori, and Makoto Yamamoto. "Three-Dimensional Trajectory and Impingement Simulation of Ice Crystals Considering State Changes on the Rotor Blade of an Axial Fan." Aerospace 11, no. 1 (2023): 2. http://dx.doi.org/10.3390/aerospace11010002.
Full textAbstract:
Ice crystal icing occurs in jet engine compressors, which can severely degrade jet engine performance. In this study, we developed an ice crystal trajectory simulation, considering the state changes of ice crystals with a forced convection model, indicating a significant difference in impinging ice crystal content on the blade for tiny ice crystals. Then, ice crystal trajectory simulations were performed for the rotor blade of an axial fan to investigate the effects of ice crystal size and relative humidity on collision characteristics. The results indicate that the surrounding air affects the composition of tiny ice crystals before collision, and the flight time until impingement on the rotor blade varies significantly depending on the span position. Among them, ice crystals with a diameter of 50 μm impinge with water content that is most likely to adhere to the blade. Three-dimensional simulation results show that many ice crystals impinge not only on the leading edge, where icing occurs as revealed by the two-dimensional simulations but also on the trailing edge of the hub side. This study emphasizes the importance of evaluating the three-dimensional impingement position and water content in the prediction of ice crystal icing.
13
Shcherbakov, Valery, Jean-François Gayet, Brad Baker, and Paul Lawson. "Light Scattering by Single Natural Ice Crystals." Journal of the Atmospheric Sciences 63, no. 5 (2006): 1513–25. http://dx.doi.org/10.1175/jas3690.1.
Full textAbstract:
Abstract During the South Pole Ice Crystal Experiment, angular scattering intensities (ASIs) of single ice crystals formed in natural conditions were measured for the first time with the polar nephelometer instrument. The microphysical properties of the ice crystals were simultaneously obtained with a cloud particle imager. The observations of the scattering properties of numerous ice crystals reveal high variability of the ASIs in terms of magnitude and distribution over scattering angles. To interpret observed ASI features, lookup tables were computed with a modified ray tracing code, which takes into account the optical geometry of the polar nephelometer. The numerical simulations consider a wide range of input parameters for the description of the ice crystal properties (particle orientation, aspect ratio, surface roughness, and internal inclusions). A new model of surface roughness, which assumes the Weibull statistics, was proposed. The simulations reproduce the overwhelming majority of the observed ASIs features and trace very well the quasi-specular reflection from crystal facets. The discrepancies observed between the model and the experimental data correspond to the rays, which pass through the ice crystal and are scattered toward the backward angles. This feature may be attributed to the internal structure of the ice crystals that should be considered in modeling refinements.
14
Egorov, B. P. "Anisotropy of the friction forces of rest and sliding frictionof single crystals of ice." Arctic and Antarctic Research 68, no. 4 (2022): 406–19. http://dx.doi.org/10.30758/0555-2648-2022-68-4-406-419.
Full textAbstract:
The properties of the ice of natural reservoirs are due to its crystalline structure. The dependence of the mechanical and strength characteristics of single ice crystals on the angle between the direction of application of force to a single crystal and the direction of its C-axis is known. Basically, this dependence is due to the possibility of the base plates of a single crystal of ice sliding relative to each other. In physics, in addition to the mechanical and strength characteristics of a solid, the properties of the surfaces of a solid state, manifested in the process of friction, are of great importance. The friction of two single crystals of ice relative to each other has been investigated in experiments on rest friction and sliding friction. From an artificially grown plate of a single ice crystal, samples of single crystals of ice with a certain orientation of the C-axis were made for the experiment. The measurement of the rest friction coefficient of a single ice crystal was realized according to the classical scheme of recording the minimum angle at which the single crystal began to roll down an inclined surface. The dependence of the rest friction coefficient of ice single crystals on the mutual orientation of the C-axes of single crystals relative to each other was discovered. The coefficients of rest friction in the case that the C-axes of single ice crystals are parallel to each other significantly exceed those obtained when the C-axes of single ice crystals are perpendicular to each other. Measurements have shown that the anisotropy of sliding friction increases with increasing initial velocity of the single crystal on the surface of the second single crystal. This is explained by the fact that with the growth of the path traveled by the M2 crystal, the time of interaction of single crystals of ice also increases, during which the properties of the anisotropy of single crystals of ice relative to sliding friction are manifested. Studies have shown the presence of anisotropy of the friction forces of rest and friction of sliding of a pair of single crystals of ice.
15
Pasquier, Julie Thérèse, Jan Henneberger, Fabiola Ramelli, et al. "Conditions favorable for secondary ice production in Arctic mixed-phase clouds." Atmospheric Chemistry and Physics 22, no. 23 (2022): 15579–601. http://dx.doi.org/10.5194/acp-22-15579-2022.
Full textAbstract:
Abstract. The Arctic is very susceptible to climate change and thus is warming much faster than the rest of the world. Clouds influence terrestrial and solar radiative fluxes and thereby impact the amplified Arctic warming. The partitioning of thermodynamic phases (i.e., ice crystals and water droplets) within mixed-phase clouds (MPCs) especially influences their radiative properties. However, the processes responsible for ice crystal formation remain only partially characterized. In particular, so-called secondary ice production (SIP) processes, which create supplementary ice crystals from primary ice crystals and the environmental conditions that they occur in, are poorly understood. The microphysical properties of Arctic MPCs were measured during the Ny-Ålesund AeroSol Cloud ExperimENT (NASCENT) campaign to obtain a better understanding of the atmospheric conditions favorable for the occurrence of SIP processes. To this aim, the in situ cloud microphysical properties retrieved by a holographic cloud imager mounted on a tethered balloon system were complemented by ground-based remote sensing and ice-nucleating particle measurements. During the 6 d investigated in this study, SIP occurred during about 40 % of the in-cloud measurements, and high SIP events with number concentrations larger than 10 L−1 of small pristine ice crystals occurred in 4 % of the in-cloud measurements. This demonstrates the role of SIP for Arctic MPCs. The highest concentrations of small pristine ice crystals were produced at temperatures between −5 and −3 ∘C and were related to the occurrence of supercooled large droplets freezing upon collision with ice crystals. This suggests that a large fraction of ice crystals in Arctic MPCs are produced via the droplet-shattering mechanism. From evaluating the ice crystal images, we could identify ice–ice collision as a second SIP mechanism that dominated when fragile ice crystals were observed. Moreover, SIP occurred over a large temperature range and was observed in up to 80 % of the measurements down to −24 ∘C due to the occurrence of ice–ice collisions. This emphasizes the importance of SIP at temperatures below −8 ∘C, which are currently not accounted for in most numerical weather models. Although ice-nucleating particles may be necessary for the initial freezing of water droplets, the ice crystal number concentration is frequently determined by secondary production mechanisms.
16
Lorv, Janet S. H., David R. Rose, and Bernard R. Glick. "Bacterial Ice Crystal Controlling Proteins." Scientifica 2014 (2014): 1–20. http://dx.doi.org/10.1155/2014/976895.
Full textAbstract:
Across the world, many ice active bacteria utilize ice crystal controlling proteins for aid in freezing tolerance at subzero temperatures. Ice crystal controlling proteins include both antifreeze and ice nucleation proteins. Antifreeze proteins minimize freezing damage by inhibiting growth of large ice crystals, while ice nucleation proteins induce formation of embryonic ice crystals. Although both protein classes have differing functions, these proteins use the same ice binding mechanisms. Rather than direct binding, it is probable that these protein classes create an ice surface prior to ice crystal surface adsorption. Function is differentiated by molecular size of the protein. This paper reviews the similar and different aspects of bacterial antifreeze and ice nucleation proteins, the role of these proteins in freezing tolerance, prevalence of these proteins in psychrophiles, and current mechanisms of protein-ice interactions.
17
Hansen, Kaj M., Anders Svensson, Yun Wang, and Jørgen Peder Steffensen. "Properties of GRIP ice crystals from around Greenland interstadial 3." Annals of Glaciology 35 (2002): 531–37. http://dx.doi.org/10.3189/172756402781816834.
Full textAbstract:
AbstractIce-crystal textures (sizes and shapes) and fabrics (c-axis orientations) have been determined in 3 m of vertical thin sections from the Greenland Icecore Project (GRIP) ice core. the samples cover ice from before, during and after Greenland interstadial 3 (IS3) that occurred about 25 kyr BP. the texture of 60 000 crystals has been obtained from stacked digital images by semi-automated methods, and the fabric of 5000 selected crystals has been measured on the Automatic Ice Fabric Analyzer at the Alfred Wegener Institute, Bremerhaven. the area distribution function of the crystals is close to a log normal distribution, and the mean area is found to be 3.36 mm2 in ice from IS3, and 3.04 mm2 in ice from colder periods before and after IS3. the overall c-axis orientations show a strong single maximum with vertical orientation. These results agree well with earlier GRIP fabric studies obtained by manual methods. from comparisons of crystal areas with the concentrations of dust, Ca2+, SO42–, Cl– and NO3– in the ice we determine that NO3– correlates best with crystal areas. Crystals within clearly visible cloudy bands are significantly smaller than the surrounding crystals, and their c-axis orientations are less well confined than the average.
18
Swanson, Brian D., and Jon Nelson. "Low-temperature triple-capillary cryostat for ice crystal growth studies." Atmospheric Measurement Techniques 12, no. 11 (2019): 6143–52. http://dx.doi.org/10.5194/amt-12-6143-2019.
Full textAbstract:
Abstract. Ice crystals come in a remarkable variety of shapes and sizes that affect a cloud's radiative properties. To better understand the growth of these crystals, we built an improved capillary cryostat (CC2) designed to reduce potential instrumental artifacts that may have influenced earlier measurements. In CC2, a crystal forms at the end of one, two, or three well-separated, ultrafine capillaries to minimize both potential crystal–crystal and crystal–substrate interaction effects. The crystals can be initiated using several ice-nucleation modes. The cryostat has two vapor-source chambers on either side of the growth chamber, each allowing independent control of the growth chamber supersaturation. Crystals can be grown under a range of air pressures, and the supersaturation conditions in the growth chamber can be rapidly changed by switching between the two vapor-source chambers using a sliding valve. Crystals grow fixed to the capillary in a uniform, stagnant environment, and their orientation can be manipulated to measure the growth rate of each face. The high thermal mass of CC2 increases the stability and uniformity of the thermodynamic conditions surrounding the crystals. Here we describe the new instrument and present several sample observations.
19
Bourdages, L., T. J. Duck, G. Lesins, J. R. Drummond, and E. W. Eloranta. "Physical properties of High Arctic tropospheric particles during winter." Atmospheric Chemistry and Physics 9, no. 18 (2009): 6881–97. http://dx.doi.org/10.5194/acp-9-6881-2009.
Full textAbstract:
Abstract. A climatology of particle scattering properties in the wintertime High Arctic troposphere, including vertical distributions and effective radii, is presented. The measurements were obtained using a lidar and cloud radar located at Eureka, Nunavut Territory (80° N, 86° W). Four different particle groupings are considered: boundary-layer ice crystals, ice clouds, mixed-phase clouds, and aerosols. Two-dimensional histograms of occurrence probabilities against depolarization, radar/lidar colour ratio and height are given. Colour ratios are related to particle minimum dimensions (i.e., widths rather than lengths) using a Mie scattering model. Ice cloud crystals have effective radii spanning 25–220 µm, with larger particles observed at lower altitudes. Topographic blowing snow residuals in the boundary layer have the smallest crystals at 15–70 µm. Mixed-phase clouds have water droplets and ice crystal precipitation in the 5–40 µm and 40–220 µm ranges, respectively. Ice cloud crystals have depolarization decreasing with height. The depolarization trend is associated with the large ice crystal sub-population. Small crystals depolarize more than large ones in ice clouds at a given altitude, and show constant modal depolarization with height. Ice clouds in the mid-troposphere are sometimes observed to precipitate to the ground. Water clouds are constrained to the lower troposphere (0.5–3.5 km altitude). Aerosols are most abundant near the ground and are frequently mixed with the other particle types. The data are used to construct a classification chart for particle scattering in wintertime Arctic conditions.
20
Zhang, Huiying, Xia Li, Fabiola Ramelli, Robert O. David, Julie Pasquier, and Jan Henneberger. "IceDetectNet: a rotated object detection algorithm for classifying components of aggregated ice crystals with a multi-label classification scheme." Atmospheric Measurement Techniques 17, no. 24 (2024): 7109–28. https://doi.org/10.5194/amt-17-7109-2024.
Full textAbstract:
Abstract. The shape of ice crystals affects their radiative properties, growth rate, fall speed, and collision efficiency; thus, it plays a significant role in cloud optical properties and precipitation formation. Ambient conditions, like temperature and humidity, determine the basic habit of ice crystals, while microphysical processes, such as riming and aggregation, further shape them, resulting in a diverse set of ice crystal shapes and effective densities. Current classification algorithms face two major challenges: (1) ice crystals are often classified as a whole (at the image scale), necessitating identification of the dominant component of aggregated ice crystals, and (2) single-label classifications lead to information loss because of the compromise between basic habit and microphysical process information. To address these limitations, we present a two-pronged solution here: (1) a rotated object detection algorithm (IceDetectNet) that classifies each component of an aggregated ice crystal individually and (2) a multi-label classification scheme that considers both basic habits and physical processes simultaneously. IceDetectNet was trained and tested on two independent datasets obtained by a holographic imager during the NASCENT campaign in Ny-Ålesund, Svalbard, in November 2019 and April 2020. The algorithm correctly classified 92 % of the ice crystals as either aggregate or non-aggregate and achieved an overall accuracy of 86 % for basic habits and 82 % for microphysical process classification. At the component scale, IceDetectNet demonstrated high detection and classification accuracy across all sizes, indicating its ability to effectively classify individual components of aggregated ice crystals. Furthermore, the algorithm demonstrated a good generalization ability by classifying ice crystals from an independent generalization dataset with overall accuracies above 70 %. IceDetectNet can provide a deeper understanding of ice crystal shapes, leading to better estimates of ice crystal mass, fall velocity, and radiative properties; therefore, it has the potential to improve precipitation forecasts and climate projections.
21
Gerber, H., and P. J. DeMott. "Response of FSSP-100 and PVM-100A to Small Ice Crystals." Journal of Atmospheric and Oceanic Technology 31, no. 10 (2014): 2145–55. http://dx.doi.org/10.1175/jtech-d-13-00228.1.
Full textAbstract:
Abstract Correction factors Cf are derived for ice-crystal volume and effective radius Re, measured by Forward Scattering Spectrometer Probe (FSSP) and Particulate Volume Monitor (PVM) that are known to overestimate both parameters for nonspherical particles. Correction factors are based on ice-crystal volume and the projected area of randomly oriented model ice crystals with column, rosette, capped-column, and dendrite habits described by Takano and Liou. In addition, Cf are calculated for oblate and prolate spheroids. To test Cf, both probes are compared to small, predominately solid hexagonal ice-crystal plates and columns generated in the Colorado State University (CSU) Dynamic Cloud Chamber (DCC). The tendency of heat released by the PVM (placed inside the chamber) to evaporate ice crystals and the smaller upper size range of the PVM than the size range of the FSSP caused large differences in the probes’ outputs for most comparisons in the DCC. Correction factors improved the accuracy of Re measured by the FSSP for the solid hexagonal crystals, and both probes produced similar results for the projected area and ice water content when crystal sizes fell within the probes’ size ranges. The modification for minimizing ice-crystal shattering and the application of Cf for forward scatter probes such as the FSSP suggests the probes’ improved usefulness for measuring small ambient ice crystals.
22
Santachiara, Gianni, Franco Belosi, and Franco Prodi. "The Mystery of Ice Crystal Multiplication in a Laboratory Experiment." Journal of the Atmospheric Sciences 71, no. 1 (2013): 89–97. http://dx.doi.org/10.1175/jas-d-13-0117.1.
Full textAbstract:
Abstract This paper addresses the problem of the large discrepancies between ice crystal concentrations in clouds and the number of ice nuclei in nearby clear air reported in published papers. Such discrepancies cannot always be explained, even by taking into account both primary and secondary ice formation processes. A laboratory experiment was performed in a cylindrical column placed in a cold room at atmospheric pressure and temperature in the −12° to −14°C range. Supercooled droplets were nucleated in the column, in the absence of aerosol ice nuclei, by injecting ice crystals generated outside in a small syringe. A rapid increase in the ice crystal concentration was observed in the absence of any known ice multiplication. The ratio between the mean number of ice crystals in the column, after complete droplet vaporization, and the number of ice crystals introduced in the column was about 10:1. The presence of small ice crystals (introduced at the top of the column) in the unstable system (supercooled droplets) appears to trigger the transformation in the whole supercooled liquid cloud. A possible explanation could be that the rapidly evaporating droplets cool sufficiently to determine a homogeneous nucleation.
23
Magee, N. B., A. Miller, M. Amaral, and A. Cumiskey. "Mesoscopic surface roughness of ice crystals pervasive across a wide range of ice crystal conditions." Atmospheric Chemistry and Physics Discussions 14, no. 6 (2014): 8393–418. http://dx.doi.org/10.5194/acpd-14-8393-2014.
Full textAbstract:
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 where the 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, at super-saturated and sub-saturated 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 phenomena interpreted as evidence of 2-D nucleation. New knowledge of 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 Supplement videos of ice growth and sublimation are provided.
24
Magee, N. B., A. Miller, M. Amaral, and A. Cumiskey. "Mesoscopic surface roughness of ice crystals pervasive across a wide range of ice crystal conditions." Atmospheric Chemistry and Physics 14, no. 22 (2014): 12357–71. http://dx.doi.org/10.5194/acp-14-12357-2014.
Full textAbstract:
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.
25
Kim, Chae Un, Yi-Fan Chen, Mark W. Tate, and Sol M. Gruner. "Pressure-induced high-density amorphous ice in protein crystals." Journal of Applied Crystallography 41, no. 1 (2008): 1–7. http://dx.doi.org/10.1107/s0021889807048820.
Full textAbstract:
Crystal cryocooling has been used in X-ray protein crystallography to mitigate radiation damage during diffraction data collection. However, cryocooling typically increases crystal mosaicity and often requires a time-consuming search for cryoprotectants. A recently developed high-pressure cryocooling method reduces crystal damage relative to traditional cryocooling procedures and eases or eliminates the need to screen for cryoprotectants. It has been proposed that the formation of high-density amorphous (HDA) ice within the protein crystal is responsible for the excellent diffraction quality of the high-pressure cryocooled crystals. This paper reports X-ray data that confirm the presence of HDA ice in the high-pressure cryocooled protein crystallization solution and protein crystals analyzed at ambient pressure. Diffuse scattering with a spacing characteristic of HDA ice is seen at low temperatures. This scattering then becomes characteristic successively to low-density amorphous, cubic and hexagonal ice phases as the temperature is gradually raised from 80 to 230 K, and seems to be highly correlated with the diffraction quality of crystals.
26
Forster, Linda, and Bernhard Mayer. "Ice crystal characterization in cirrus clouds III: retrieval of ice crystal shape and roughness from observations of halo displays." Atmospheric Chemistry and Physics 22, no. 23 (2022): 15179–205. http://dx.doi.org/10.5194/acp-22-15179-2022.
Full textAbstract:
Abstract. In this study, which is the third part of the HaloCam series after Forster et al. (2017, 2020), we present a novel technique to retrieve quantitative information about ice crystal optical and microphysical properties using ground-based imaging observations of halo displays. Comparing HaloCam's calibrated RGB images of 22 and 46∘ halo observations against a lookup table of simulated radiances, this technique allows the retrieval of the sizes and shapes of randomly oriented crystals as well as the fraction of smooth and rough ice crystals for cirrus clouds. We analyzed 4400 HaloCam images between September 2015 and November 2016 showing a visible 22∘ halo. The optical properties of hexagonal 8-element aggregates of columns with a mean ice crystal effective radius of about 20 µm and a mixture of 37 % smooth and 63 % rough crystals on average best match the HaloCam observations. Implemented on different sites, HaloCam in combination with the machine-learning-based halo detection algorithm HaloForest can provide a consistent dataset for climatological studies of ice crystal properties representing typical cirrus clouds. Representative ice crystal optical properties are required for remote sensing of cirrus clouds as well as climate modeling. Since ground-based passive imaging observations provide information about the forward scattering part of the ice crystal optical properties, the results of this work ideally complement the results of satellite-based and airborne studies.
27
Pollard, W. H., and H. M. French. "The Internal Structure and Ice Crystallography of Seasonal Frost Mounds." Journal of Glaciology 31, no. 108 (1985): 157–62. http://dx.doi.org/10.1017/s0022143000006407.
Full textAbstract:
AbstractThe crystal character of the ice core within frost blisters supports the hypothesis that groundwater injection into residual zones of the active layer followed by rapid freezing is the primary growth mechanism for these features. The ice core is characterized by an upper zone of relatively small randomly arranged equigranular ice crystals which change with increasing depth to columnar anhedral crystals, commonly exceeding 200 mm in length, and with crystal diameters ranging between 25 and 35 mm. Petrofabric analyses show that thec-axis orientations are normal to crystal elongations, with crystal growth along the basal plane in ana-axis direction. These observations eliminate ice segregation as a possible growth mechanism, thereby distinguishing seasonal frost mounds from palsas.
28
Pollard, W. H., and H. M. French. "The Internal Structure and Ice Crystallography of Seasonal Frost Mounds." Journal of Glaciology 31, no. 108 (1985): 157–62. http://dx.doi.org/10.3189/s0022143000006407.
Full textAbstract:
AbstractThe crystal character of the ice core within frost blisters supports the hypothesis that groundwater injection into residual zones of the active layer followed by rapid freezing is the primary growth mechanism for these features. The ice core is characterized by an upper zone of relatively small randomly arranged equigranular ice crystals which change with increasing depth to columnar anhedral crystals, commonly exceeding 200 mm in length, and with crystal diameters ranging between 25 and 35 mm. Petrofabric analyses show that the c-axis orientations are normal to crystal elongations, with crystal growth along the basal plane in an a-axis direction. These observations eliminate ice segregation as a possible growth mechanism, thereby distinguishing seasonal frost mounds from palsas.
29
Weitzel, Maximilian, Subir K. Mitra, Miklós Szakáll, Jacob P. Fugal, and Stephan Borrmann. "Application of holography and automated image processing for laboratory experiments on mass and fall speed of small cloud ice crystals." Atmospheric Chemistry and Physics 20, no. 23 (2020): 14889–901. http://dx.doi.org/10.5194/acp-20-14889-2020.
Full textAbstract:
Abstract. An ice cloud chamber was developed at the Johannes Gutenberg University of Mainz for generating several thousand data points for mass and sedimentation velocity measurements of ice crystals with sizes less than 150 µm. Ice nucleation was initiated from a cloud of supercooled droplets by local cooling using a liquid nitrogen cold finger. Three-dimensional tracks of ice crystals falling through the slightly supersaturated environment were obtained from the reconstruction of sequential holographic images, automated detection of the crystals in the hologram reconstructions, and particle tracking. Through collection of the crystals and investigation under a microscope before and after melting, crystal mass was determined as a function of size. The experimentally obtained mass versus diameter (m(D)) power law relationship resulted in lower masses for small ice crystals than from commonly adopted parameterizations. Thus, they did not support the currently accepted extrapolation of relationships measured for larger crystal sizes. The relationship between Best (X) and Reynolds (Re) numbers for columnar crystals was found to be X=15.3 Re1.2, which is in general agreement with literature parameterizations.
30
Bayer-Giraldi, Maddalena, Gen Sazaki, Ken Nagashima, Sepp Kipfstuhl, Dmitry A. Vorontsov, and Yoshinori Furukawa. "Growth suppression of ice crystal basal face in the presence of a moderate ice-binding protein does not confer hyperactivity." Proceedings of the National Academy of Sciences 115, no. 29 (2018): 7479–84. http://dx.doi.org/10.1073/pnas.1807461115.
Full textAbstract:
Ice-binding proteins (IBPs) affect ice crystal growth by attaching to crystal faces. We present the effects on the growth of an ice single crystal caused by an ice-binding protein from the sea ice microalga Fragilariopsis cylindrus (fcIBP) that is characterized by the widespread domain of unknown function 3494 (DUF3494) and known to cause a moderate freezing point depression (below 1 °C). By the application of interferometry, bright-field microscopy, and fluorescence microscopy, we observed that the fcIBP attaches to the basal faces of ice crystals, thereby inhibiting their growth in the c direction and resulting in an increase in the effective supercooling with increasing fcIBP concentration. In addition, we observed that the fcIBP attaches to prism faces and inhibits their growth. In the event that the effective supercooling is small and crystals are faceted, this process causes an emergence of prism faces and suppresses crystal growth in the a direction. When the effective supercooling is large and ice crystals have developed into a dendritic shape, the suppression of prism face growth results in thinner dendrite branches, and growth in the a direction is accelerated due to enhanced latent heat dissipation. Our observations clearly indicate that the fcIBP occupies a separate position in the classification of IBPs due to the fact that it suppresses the growth of basal faces, despite its moderate freezing point depression.
31
Rees Jones, David W., and Andrew J. Wells. "Frazil-ice growth rate and dynamics in mixed layers and sub-ice-shelf plumes." Cryosphere 12, no. 1 (2018): 25–38. http://dx.doi.org/10.5194/tc-12-25-2018.
Full textAbstract:
Abstract. The growth of frazil or granular ice is an important mode of ice formation in the cryosphere. Recent advances have improved our understanding of the microphysical processes that control the rate of ice-crystal growth when water is cooled beneath its freezing temperature. These advances suggest that crystals grow much faster than previously thought. In this paper, we consider models of a population of ice crystals with different sizes to provide insight into the treatment of frazil ice in large-scale models. We consider the role of crystal growth alongside the other physical processes that determine the dynamics of frazil ice. We apply our model to a simple mixed layer (such as at the surface of the ocean) and to a buoyant plume under a floating ice shelf. We provide numerical calculations and scaling arguments to predict the occurrence of frazil-ice explosions, which we show are controlled by crystal growth, nucleation, and gravitational removal. Faster crystal growth, higher secondary nucleation, and slower gravitational removal make frazil-ice explosions more likely. We identify steady-state crystal size distributions, which are largely insensitive to crystal growth rate but are affected by the relative importance of secondary nucleation to gravitational removal. Finally, we show that the fate of plumes underneath ice shelves is dramatically affected by frazil-ice dynamics. Differences in the parameterization of crystal growth and nucleation give rise to radically different predictions of basal accretion and plume dynamics, and can even impact whether a plume reaches the end of the ice shelf or intrudes at depth.
32
Chen, Jen-Ping, and Tzu-Chin Tsai. "Triple-Moment Modal Parameterization for the Adaptive Growth Habit of Pristine Ice Crystals." Journal of the Atmospheric Sciences 73, no. 5 (2016): 2105–22. http://dx.doi.org/10.1175/jas-d-15-0220.1.
Full textAbstract:
Abstract A three-moment modal parameterization scheme was developed for describing variations in the shape of cloud ice crystals during growth by vapor deposition. The shape of ice crystals is represented using the volume-weighted aspect ratio, while the size spectrum of the crystal population is described using a three-parameter gamma function. Verified with binned spectral calculations, the proposed modal scheme performed quite accurately in the evolution of the mass and shape of cloud ice crystals growing under idealized conditions. The associated error is within 1% in mass after 1000 s of growth under water saturation. When the ventilation effect is taken into account, the error remains within 5%. Error with regard to the bulk aspect ratio is generally about 3%. A failure to take into account the ice crystal shape led to a 45% underestimation in mass growth. Using only two moments to describe the gamma distribution led to a 37% underestimation in mass and 28% underestimation in the bulk aspect ratio of the ice crystals. The proposed scheme is able to capture the shape memory effect and the gradual adaptation of ice crystal aspect ratios to a new growth habit regime.
33
GUO, Qilei, Jie DU, Feng QIAN, and Ning DING. "Numerical Study of Particle Impingement on Aeroengine under Mixed-Phase Conditions." Mechanics 30, no. 5 (2024): 415–22. http://dx.doi.org/10.5755/j02.mech.31501.
Full textAbstract:
In this approach, considering to ice crystal sticking effects, a numerical model was established to solve the particle impingement property of a large bypass ratio aeroengine under mixed-phase icing conditions. The collection efficiency of droplets obtained by the proposed model is are well in agreement with the literature and the collection efficiency of ice crystals is significantly higher than that of droplets due to the greater inertial force. The mechanism of liquid film acting on the ice crystal adhesion affect was investigated. It is found that the greater melt ratio can lead to more sufficient liquid water and more extended wetting limit, which have more significant capability of sticking ice crystals. Meanwhile, due to ice crystals subjected to centrifugal force, the sticking coefficient of ice crystal will cliff-like drop, and the cliff-like effect is more pronounced accompanied by the greater centrifugal force.
34
Voigtländer, Jens, Cedric Chou, Henner Bieligk, et al. "Surface roughness during depositional growth and sublimation of ice crystals." Atmospheric Chemistry and Physics 18, no. 18 (2018): 13687–702. http://dx.doi.org/10.5194/acp-18-13687-2018.
Full textAbstract:
Abstract. Ice surface properties can modify the scattering properties of atmospheric ice crystals and therefore affect the radiative properties of mixed-phase and cirrus clouds. The Ice Roughness Investigation System (IRIS) is a new laboratory setup designed to investigate the conditions under which roughness develops on single ice crystals, based on their size, morphology and growth conditions (relative humidity and temperature). Ice roughness is quantified through the analysis of speckle in 2-D light-scattering patterns. Characterization of the setup shows that a supersaturation of 20 % with respect to ice and a temperature at the sample position as low as −40 ∘C could be achieved within IRIS. Investigations of the influence of humidity show that higher supersaturations with respect to ice lead to enhanced roughness and irregularities of ice crystal surfaces. Moreover, relative humidity oscillations lead to gradual “ratcheting-up” of roughness and irregularities, as the crystals undergo repeated growth–sublimation cycles. This memory effect also appears to result in reduced growth rates in later cycles. Thus, growth history, as well as supersaturation and temperature, influences ice crystal growth and properties, and future atmospheric models may benefit from its inclusion in the cloud evolution process and allow more accurate representation of not just roughness but crystal size too, and possibly also electrification properties.
35
Lu, Shengfang, Weijian Chen, Dalin Zhang, Zihao Zhang, and Guangya Zhu. "Investigation on Phase Transition and Collection Characteristics of Non-Spherical Ice Crystals with Eulerian and Lagrangian Methods." Aerospace 11, no. 4 (2024): 299. http://dx.doi.org/10.3390/aerospace11040299.
Full textAbstract:
Ice crystal icing occurs in jet engine compressors, which can severely degrade jet engine performance. In this paper, two different numerical calculation methods, the Eulerian method and the Lagrangian method, were used to evaluate the dynamics, mass transfer, heat transfer, phase transition and trajectory of ice crystals. Then, we studied the effects of initial diameter, initial sphericity, initial temperature of ice crystal, and relative humidity of airflow on the phase transition and collection characteristics of ice crystal particles. Results indicate that the non-spherical characteristics of ice crystals have a significant impact on their impingement limits and collection characteristics. The collection coefficient of unmelted ice crystals is positively correlated with the initial particle diameter and sphericity, and negatively correlated with the initial particle temperature and the relative humidity of airflow. The melting rate of ice crystal particles on the impact surface increases exponentially with the initial diameter of the particles, linearly increases with the relative humidity of the airflow and initial temperature of the particles, and exponentially decreases with the sphericity of the particles.
36
Miyamoto, Atsushi, Ilka Weikusat, and Takeo Hondoh. "Complete determination of ice crystal orientation using Laue X-ray diffraction method." Journal of Glaciology 57, no. 201 (2011): 103–10. http://dx.doi.org/10.3189/002214311795306754.
Full textAbstract:
AbstractIce crystal orientation fabric data from ice cores contain important information concerning the internal structure and the flow behaviour of ice sheets. When ice cores are recovered from the Antarctic and Greenland ice sheets, crystal orientation measurements are performed immediately to obtain fundamental physical property information. In the past, we have measured the c-axis orientation of ice crystals by a manual optical method using a universal stage. This method is very time-consuming, involving tedious work in a cold laboratory. Recently, automated systems have been developed that enable measurement of c-axis orientation, grain size and other microstructures. However, in order to detect the full crystal orientation of an ice crystal, we also need information on its a-axis orientation. A variety of other crystal orientation measurement methods have previously been discussed, but some shortcomings for ice-core studies cannot be neglected. We have developed a crystal-orientation analysing device using the Laue X-ray diffraction method. As this device can measure the orientations of all crystal axes with high accuracy, it is possible to obtain new microstructure information on natural ice crystals. For the first time, we are able to quantify very low subgrain misorientation angles in polar ice-core samples, allowing us to investigate micro-deformation features of individual crystals. Here we discuss the analysis process, which is customized to measure standard ice thin sections, and show preliminary results.
37
Garrett, T. J., M. B. Kimball, G. G. Mace, and D. G. Baumgardner. "Observing cirrus halos to constrain in-situ measurements of ice crystal size." Atmospheric Chemistry and Physics Discussions 7, no. 1 (2007): 1295–325. http://dx.doi.org/10.5194/acpd-7-1295-2007.
Full textAbstract:
Abstract. In this study, characteristic optical sizes of ice crystals in synoptic cirrus are determined using airborne measurements of ice crystal size distributions, optical extinction and water content. The measurements are compared with coincident visual observations of ice cloud optical phenomena, in particular the 22° and 46° halos. In general, the scattering profiles derived from the in-situ cloud probe measurements are consistent with the observed halo characteristics. It is argued that this implies that the measured ice crystals were small, probably with characteristic optical radii between 10 and 20 μm. There is a current contention that in-situ measurements of high concentrations of small ice crystals reflect artifacts from the shattering of large ice crystals on instrument inlets. Significant shattering cannot be entirely excluded using this approximate technique, but it is not indicated. On the basis of the in-situ measurements, a parameterization is provided that relates the optical effective radius of ice crystals to the temperature in mid-latitude synoptic cirrus.
38
XU, AIXIANG, ZHIQIANG LIU, TENGLEI ZHAO, and XIAOXIAO WANG. "POPULATION BALANCE MODEL OF ICE CRYSTALS SIZE DISTRIBUTION DURING ICE SLURRY STORAGE." International Journal of Air-Conditioning and Refrigeration 22, no. 02 (2014): 1440001. http://dx.doi.org/10.1142/s201013251440001x.
Full textAbstract:
Particle size distribution and number of ice crystals have a great influence on the flow and heat transfer performance of ice slurry. A population balance model (PBM) containing population and mass balances has been built to simulate numerically the development of ice particle size distribution during adiabatic ice slurry storage. The model assumes a homogeneously mixed and long-term storage tank in which the effect of breakage and aggregation between ice crystals was considered. For solving the population balance equations (PBEs) in the PBM, a semi-discrete finite volume scheme was applied. Finally, the effect of breakage and aggregation on development of ice particle size distribution was analyzed respectively. The results show that both breakage and aggregation are the two important effects on the particle size distribution and evolution of ice particle during storage, but they have opposite effect on the development of ice crystal size. In storage, breakage and aggregation have almost equivalent effect in the initial phase, but aggregation has dominant effect at last. The PBM results are in good agreement with experimental results by Pronk et al. [Effect of long-term ice slurry storage on crystal size distribution, 5th Workshop on Ice Slurries of the IIR (2002), pp. 151–160]. Therefore, the PBM presented in this paper is able to predict the development of particle size distribution during ice slurry storage.
39
Gultepe, I., A. J. Heymsfield, P. R. Field, and D. Axisa. "Ice-Phase Precipitation." Meteorological Monographs 58 (January 1, 2017): 6.1–6.36. http://dx.doi.org/10.1175/amsmonographs-d-16-0013.1.
Full textAbstract:
AbstractIce-phase precipitation occurs at Earth’s surface and may include various types of pristine crystals, rimed crystals, freezing droplets, secondary crystals, aggregates, graupel, hail, or combinations of any of these. Formation of ice-phase precipitation is directly related to environmental and cloud meteorological parameters that include available moisture, temperature, and three-dimensional wind speed and turbulence, as well as processes related to nucleation, cooling rate, and microphysics. Cloud microphysical parameters in the numerical models are resolved based on various processes such as nucleation, mixing, collision and coalescence, accretion, riming, secondary ice particle generation, turbulence, and cooling processes. These processes are usually parameterized based on assumed particle size distributions and ice crystal microphysical parameters such as mass, size, and number and mass density. Microphysical algorithms in the numerical models are developed based on their need for applications. Observations of ice-phase precipitation are performed using in situ and remote sensing platforms, including radars and satellite-based systems. Because of the low density of snow particles with small ice water content, their measurements and predictions at the surface can include large uncertainties. Wind and turbulence affecting collection efficiency of the sensors, calibration issues, and sensitivity of ground-based in situ observations of snow are important challenges to assessing the snow precipitation. This chapter’s goals are to provide an overview for accurately measuring and predicting ice-phase precipitation. The processes within and below cloud that affect falling snow, as well as the known sources of error that affect understanding and prediction of these processes, are discussed.
40
Haapanala, Päivi, Petri Räisänen, Greg M. McFarquhar, et al. "Disk and circumsolar radiances in the presence of ice clouds." Atmospheric Chemistry and Physics 17, no. 11 (2017): 6865–82. http://dx.doi.org/10.5194/acp-17-6865-2017.
Full textAbstract:
Abstract. The impact of ice clouds on solar disk and circumsolar radiances is investigated using a Monte Carlo radiative transfer model. The monochromatic direct and diffuse radiances are simulated at angles of 0 to 8° from the center of the sun. Input data for the model are derived from measurements conducted during the 2010 Small Particles in Cirrus (SPARTICUS) campaign together with state-of-the-art databases of optical properties of ice crystals and aerosols. For selected cases, the simulated radiances are compared with ground-based radiance measurements obtained by the Sun and Aureole Measurements (SAM) instrument. First, the sensitivity of the radiances to the ice cloud properties and aerosol optical thickness is addressed. The angular dependence of the disk and circumsolar radiances is found to be most sensitive to assumptions about ice crystal roughness (or, more generally, non-ideal features of ice crystals) and size distribution, with ice crystal habit playing a somewhat smaller role. Second, in comparisons with SAM data, the ice cloud optical thickness is adjusted for each case so that the simulated radiances agree closely (i.e., within 3 %) with the measured disk radiances. Circumsolar radiances at angles larger than ≈ 3° are systematically underestimated when assuming smooth ice crystals, whereas the agreement with the measurements is better when rough ice crystals are assumed. Our results suggest that it may well be possible to infer the particle roughness directly from ground-based SAM measurements. In addition, the results show the necessity of correcting the ground-based measurements of direct radiation for the presence of diffuse radiation in the instrument's field of view, in particular in the presence of ice clouds.
41
Nomura, Daiki, Philipp Assmy, Gernot Nehrke, et al. "Characterization of ikaite (CaCO3·6H2O) crystals in first-year Arctic sea ice north of Svalbard." Annals of Glaciology 54, no. 62 (2013): 125–31. http://dx.doi.org/10.3189/2013aog62a034.
Full textAbstract:
AbstractWe identified ikaite crystals (CaCO3·6H2O) and examined their shape and size distribution in first-year Arctic pack ice, overlying snow and slush layers during the spring melt onset north of Svalbard. Additional measurements of total alkalinity (TA) were made for melted snow and sea-ice samples. Ikaite crystals were mainly found in the bottom of the snowpack, in slush and the surface layers of the sea ice where the temperature was generally lower and salinity higher than in the ice below. Image analysis showed that ikaite crystals were characterized by a roughly elliptical shape and a maximum caliper diameter of 201.0±115.9 μm (n = 918). Since the ice-melting season had already started, ikaite crystals may already have begun to dissolve, which might explain the lack of a relationship between ikaite crystal size and sea-ice parameters (temperature, salinity, and thickness of snow and ice). Comparisons of salinity and TA profiles for melted ice samples suggest that the precipitation/dissolution of ikaite crystals occurred at the top of the sea ice and the bottom of the snowpack during ice formation/melting processes.
42
Kärcher, B., A. Dörnbrack, and I. Sölch. "Supersaturation Variability and Cirrus Ice Crystal Size Distributions." Journal of the Atmospheric Sciences 71, no. 8 (2014): 2905–26. http://dx.doi.org/10.1175/jas-d-13-0404.1.
Full textAbstract:
Abstract Small-scale dynamical variability affects atmospheric supersaturation and therefore the development of ice clouds via uptake of water vapor on ice crystals. This variability and its implications for ice growth are difficult to capture experimentally and theoretically. By interpreting supersaturation as a stochastic variable, the authors examine the average temporal behavior of, and the link between, supersaturation fluctuations and ice crystal size distributions in upper-tropospheric cirrus clouds. The authors classify cirrus types according to their ability to dampen supersaturation fluctuations owing to depositional growth of cloud ice and study how size distributions in them respond to supersaturation variability, investigating the possibility of the occurrence of ice-supersaturated states within cirrus. Typical time scales for growth and damping impacts on supersaturation are minutes and minutes to hours, respectively, and are highly variable among cirrus types and within single clouds. Transient deviations from saturated equilibrium states can occur depending on the ice crystal number concentration and size and on the strength of the small-scale dynamical forcing. Supersaturation preferentially occurs in cloud regions with few small ice crystals. The authors demonstrate that supersaturation fluctuations in very thin tropical tropopause cirrus create long-lived supersaturated states. Furthermore, they potentially generate few large ice crystals, broadening size distributions, and significantly enhance water mass fluxes due to sedimentation. Although not studied here, they may also allow new ice crystals to nucleate. Implications of these findings for those clouds to dehydrate air entering the lower stratosphere are discussed and future research needs are outlined.
43
Bar-Dolev, Maya, Yeliz Celik, J. S. Wettlaufer, Peter L. Davies, and Ido Braslavsky. "New insights into ice growth and melting modifications by antifreeze proteins." Journal of The Royal Society Interface 9, no. 77 (2012): 3249–59. http://dx.doi.org/10.1098/rsif.2012.0388.
Full textAbstract:
Antifreeze proteins (AFPs) evolved in many organisms, allowing them to survive in cold climates by controlling ice crystal growth. The specific interactions of AFPs with ice determine their potential applications in agriculture, food preservation and medicine. AFPs control the shapes of ice crystals in a manner characteristic of the particular AFP type. Moderately active AFPs cause the formation of elongated bipyramidal crystals, often with seemingly defined facets, while hyperactive AFPs produce more varied crystal shapes. These different morphologies are generally considered to be growth shapes. In a series of bright light and fluorescent microscopy observations of ice crystals in solutions containing different AFPs, we show that crystal shaping also occurs during melting. In particular, the characteristic ice shapes observed in solutions of most hyperactive AFPs are formed during melting. We relate these findings to the affinities of the hyperactive AFPs for the basal plane of ice. Our results demonstrate the relation between basal plane affinity and hyperactivity and show a clear difference in the ice-shaping mechanisms of most moderate and hyperactive AFPs. This study provides key aspects associated with the identification of hyperactive AFPs.
44
Yamashtta, Takira, Asaharu Asano, and Takayuki Ohno. "Comparison of Ice Crystals Grown from Vapour in Varying Conditions." Annals of Glaciology 6 (1985): 242–45. http://dx.doi.org/10.3189/1985aog6-1-242-245.
Full textAbstract:
In a static supercooled cloud dendrites hardly grow at about -15°C except at the pointed tip of a needle-like ice crystal or an isolated thin plate-like ice crystal. When ice crystals are moved slowly in a static supercooled cloud, dendrites grow at about -15° C and the α-axis growth rate increases as the velocity of the dendrites increases; at velocities higher than 20 cm/s, however, the a-axis growth rate decreases as the velocity increases due to the influence of heavy riming. The maximum a-axis growth rate in a supercooled cloud is observed at about -15°C in experiments growing ice crystals in free fall.
45
Yamashtta, Takira, Asaharu Asano, and Takayuki Ohno. "Comparison of Ice Crystals Grown from Vapour in Varying Conditions." Annals of Glaciology 6 (1985): 242–45. http://dx.doi.org/10.1017/s0260305500010466.
Full textAbstract:
In a static supercooled cloud dendrites hardly grow at about -15°C except at the pointed tip of a needle-like ice crystal or an isolated thin plate-like ice crystal. When ice crystals are moved slowly in a static supercooled cloud, dendrites grow at about -15° C and the α-axis growth rate increases as the velocity of the dendrites increases; at velocities higher than 20 cm/s, however, the a-axis growth rate decreases as the velocity increases due to the influence of heavy riming. The maximum a-axis growth rate in a supercooled cloud is observed at about -15°C in experiments growing ice crystals in free fall.
46
Kustova, Natalia, Alexander Konoshonkin, Victor Shishko, et al. "Depolarization Ratio for Randomly Oriented Ice Crystals of Cirrus Clouds." Atmosphere 13, no. 10 (2022): 1551. http://dx.doi.org/10.3390/atmos13101551.
Full textAbstract:
The depolarization ratio and backscattering cross sections have been calculated for shapes and size of ice crystals that are typical in cirrus clouds. The calculations are performed in the physical-optics approximation. It is shown that the depolarization ratio approaches some constant when the size of the crystals becomes much larger than the incident wavelength. For the transparent ice crystals, when absorption is absent, the magnitude of this constant strongly depends on crystal shapes. This fact allows inferring the crystal shape from magnitudes of the depolarization ratio in lidar signals. For the lidar wavelengths, where absorption of light is considerable, the depolarization ratio of lidar signals can be used for inferring crystal sizes. Such results are important for the development of algorithms interpreting the signals obtained by both ground-based and space-borne lidars.
47
Jensen, E. J., P. Lawson, B. Baker, et al. "On the importance of small ice crystals in tropical anvil cirrus." Atmospheric Chemistry and Physics Discussions 9, no. 2 (2009): 5321–70. http://dx.doi.org/10.5194/acpd-9-5321-2009.
Full textAbstract:
Abstract. In situ measurements of ice crystal concentrations and sizes made with aircraft instrumentation over the past two decades have often indicated the presence of numerous relatively small (<50 μm diameter) crystals in cirrus clouds. Further, these measurements frequently indicate that small crystals account for a large fraction of the extinction in cirrus clouds. The fact that the instruments used to make these measurements, such as the Forward Scattering Spectrometer Probe (FSSP) and the Cloud Aerosol Spectrometer (CAS), ingest ice crystals into the sample volume through inlets has led to suspicion that the indications of numerous small-crystals could be artifacts of large-crystal shattering on the instrument inlets. We present new aircraft measurements in anvil cirrus sampled during the Tropical Composition, Cloud, and Climate Coupling (TC4) campaign with the 2-Dimensional Stereo (2D-S) probe, which detects particles as small as 10 μm. The 2D-S has detector "arms" instead of an inlet tube, and therefore is expected to be less susceptible to shattering artifacts than instruments such as CAS. In addition, particle inter-arrival times are used to identify and remove shattering artifacts that occur even with the 2D-S probe. The number of shattering artifacts identified by the 2D-S interarrival time analysis ranges from a negligible contribution to an order of magnitude or more enhancement in apparent ice concentration over the natural ice concentration, depending on the abundance of large crystals and the natural small-crystal concentration. The 2D-S measurements in tropical anvil cirrus suggest that natural small-crystal concentrations are typically one to two orders of magnitude lower than those inferred from CAS. The strong correlation between the CAS/2D-S ratio of small-crystal concentrations and large-crystal concentration suggests that the discrepancy is likely caused by shattering of large crystals on the CAS inlet. We argue that past measurements with CAS in cirrus with large crystals present may contain errors due to crystal shattering, and past conclusions derived from these measurements may need to be revisited. Further, we present correlations between CAS spurious concentration and 2D-S large-crystal mass from spatially uniform anvil cirrus sampling periods as an approximate guide for estimating quantitative impact of large-crystal shattering on CAS concentrations in previous datasets. We use radiative transfer calculations to demonstrate that in the maritime anvil cirrus sampled during TC4, small crystals indicated by 2D-S contribute relatively little to cloud extinction, radiative forcing, or radiative heating in the anvils, regardless of anvil age or vertical location in the clouds. While 2D-S ice concentrations in fresh anvil cirrus may often exceed 1 cm−3, and are observed to exceed 10 cm−3 in turrets, they are typically ~0.1 cm−3 and rarely exceed 1 cm−3 (<1.4% of the time) in aged anvil cirrus. It appears that the numerous small crystals detrained from convective updrafts do not persist in the anvil cirrus sampled during TC-4. We hypothesize that isolated occurrences of higher ice concentrations in aged anvil cirrus are caused by ice nucleation driven by gravity waves.
48
Jensen, E. J., P. Lawson, B. Baker, et al. "On the importance of small ice crystals in tropical anvil cirrus." Atmospheric Chemistry and Physics 9, no. 15 (2009): 5519–37. http://dx.doi.org/10.5194/acp-9-5519-2009.
Full textAbstract:
Abstract. In situ measurements of ice crystal concentrations and sizes made with aircraft instrumentation over the past two decades have often indicated the presence of numerous relatively small (< 50 μm diameter) crystals in cirrus clouds. Further, these measurements frequently indicate that small crystals account for a large fraction of the extinction in cirrus clouds. The fact that the instruments used to make these measurements, such as the Forward Scattering Spectrometer Probe (FSSP) and the Cloud Aerosol Spectrometer (CAS), ingest ice crystals into the sample volume through inlets has led to suspicion that the indications of numerous small-crystals could be artifacts of large-crystal shattering on the instrument inlets. We present new aircraft measurements in anvil cirrus sampled during the Tropical Composition, Cloud, and Climate Coupling (TC4) campaign with the 2-Dimensional Stereo (2D-S) probe, which detects particles as small as 10 μm. The 2D-S has detector "arms" instead of an inlet tube. Since the 2D-S probe surfaces are much further from the sample volume than is the case for the instruments with inlets, it is expected that 2D-S will be less susceptible to shattering artifacts. In addition, particle inter-arrival times are used to identify and remove shattering artifacts that occur even with the 2D-S probe. The number of shattering artifacts identified by the 2D-S interarrival time analysis ranges from a negligible contribution to an order of magnitude or more enhancement in apparent ice concentration over the natural ice concentration, depending on the abundance of large crystals and the natural small-crystal concentration. The 2D-S measurements in tropical anvil cirrus suggest that natural small-crystal concentrations are typically one to two orders of magnitude lower than those inferred from CAS. The strong correlation between the CAS/2D-S ratio of small-crystal concentrations and large-crystal concentration suggests that the discrepancy is likely caused by shattering of large crystals on the CAS inlet. We argue that past measurements with CAS in cirrus with large crystals present may contain errors due to crystal shattering, and past conclusions derived from these measurements may need to be revisited. Further, we present correlations between CAS spurious concentration and 2D-S large-crystal mass from spatially uniform anvil cirrus sampling periods as an approximate guide for estimating quantitative impact of large-crystal shattering on CAS concentrations in previous datasets. We use radiative transfer calculations to demonstrate that in the maritime anvil cirrus sampled during TC4, small crystals indicated by 2D-S contribute relatively little cloud extinction, radiative forcing, or radiative heating in the anvils, regardless of anvil age or vertical location in the clouds. While 2D-S ice concentrations in fresh anvil cirrus may often exceed 1 cm−3, and are observed to exceed 10 cm−3 in turrets, they are typically ~0.1 cm−3 and rarely exceed 1 cm−3 (<1.4% of the time) in aged anvil cirrus. We hypothesize that isolated occurrences of higher ice concentrations in aged anvil cirrus may be caused by ice nucleation driven by either small-scale convection or gravity waves. It appears that the numerous small crystals detrained from convective updrafts do not persist in the anvil cirrus sampled during TC-4.
49
Mignani, Claudia, Jessie M. Creamean, Lukas Zimmermann, Christine Alewell, and Franz Conen. "New type of evidence for secondary ice formation at around −15 °C in mixed-phase clouds." Atmospheric Chemistry and Physics 19, no. 2 (2019): 877–86. http://dx.doi.org/10.5194/acp-19-877-2019.
Full textAbstract:
Abstract. Ice crystal numbers can exceed the numbers of ice-nucleating particles (INPs) observed in mixed-phase clouds (MPCs) by several orders of magnitude, also at temperatures that are colder than −8 ∘C. This disparity provides circumstantial evidence of secondary ice formation, also other than via the Hallett–Mossop process. In a new approach, we made use of the fact that planar, branched ice crystals (e.g. dendrites) grow within a relatively narrow temperature range (i.e. −12 to −17 ∘C) and can be analysed individually for INPs using a field-deployable drop-freezing assay. The novelty of our approach lies in comparing the growth temperature encoded in the habit of an individual crystal with the activation temperature of the most efficient INP contained within the same crystal to tell whether it may be the result of primary ice formation. In February and March 2018, we analysed a total of 190 dendritic crystals (∼3 mm median size) deposited within MPCs at the high-altitude research station Jungfraujoch (3580 m a.s.l.). Overall, one in eight of the analysed crystals contained an INP active at −17 ∘C or warmer, while the remaining seven most likely resulted from secondary ice formation within the clouds. The ice multiplication factor we observed was small (8), but relatively stable throughout the course of documentation. These measurements show that secondary ice can be observed at temperatures around −15 ∘C and thus advance our understanding of the extent of secondary ice formation in MPCs, even where the multiplication factor is smaller than 10.
50
Moreau, David W., Hakan Atakisi, and Robert E. Thorne. "Ice formation and solvent nanoconfinement in protein crystals." IUCrJ 6, no. 3 (2019): 346–56. http://dx.doi.org/10.1107/s2052252519001878.
Full textAbstract:
Ice formation within protein crystals is a major obstacle to the cryocrystallographic study of protein structure, and has limited studies of how the structural ensemble of a protein evolves with temperature in the biophysically interesting range from ∼260 K to the protein–solvent glass transition near 200 K. Using protein crystals with solvent cavities as large as ∼70 Å, time-resolved X-ray diffraction was used to study the response of protein and internal solvent during rapid cooling. Solvent nanoconfinement suppresses freezing temperatures and ice-nucleation rates so that ice-free, low-mosaicity diffraction data can be reliably collected down to 200 K without the use of cryoprotectants. Hexagonal ice (Ih) forms in external solvent, but internal crystal solvent forms stacking-disordered ice (Isd) with a near-random stacking of cubic and hexagonal planes. Analysis of powder diffraction from internal ice and single-crystal diffraction from the host protein structure shows that the maximum crystallizable solvent fraction decreases with decreasing crystal solvent-cavity size, and that an ∼6 Å thick layer of solvent adjacent to the protein surface cannot crystallize. These results establish protein crystals as excellent model systems for the study of nanoconfined solvent. By combining fast cooling, intense X-ray beams and fast X-ray detectors, complete structural data sets for high-value targets, including membrane proteins and large complexes, may be collected at ∼220–240 K that have much lower mosaicities and comparableBfactors, and that may allow more confident identification of ligand binding than in current cryocrystallographic practice.