DOCSLIB.ORG

Evaluating the Compressive Strength of Hail and Its Relationship To

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Evaluating the Compressive Strength of Hail and Its Relationship To Hailstone with cyclic growth ring structure and dry growth areas (cloudy) and wet growth areas (clear). Note the alternating growth types, which result from dry and wet growth conditions. ABSTRACT wind speed occurring during the hail event. as diameter increases, so does Fo and its Hail damage to building envelopes is ASTM E822-92 provides numerical meth- uniformity; however, c will decrease with clearly on the rise. This is confirmed by ods for adjusting hail falling speed based diameter increase, while uniformity of c insurance companies reporting that 2017 upon the hail’s terminal velocity and wind increases with increasedσ diameter. The hail σ was the first year that hail damage has been speed. Many people have the experience of Fo and c population distribution was devel- the most expensive insured peril for real observing hail in the form of soft slush balls, oped for each hail size bin. The kinetic ener- property claims in the United States. The while some hail is seemingly as hard as a gy (KE) σwas computed for each hail size bin. causes for this unprecedented hail dam- ball bearing. Natural hail compressive strength from age cost include more frequent damaging More than 875 natural hailstones were 875 natural hailstones from the IBHS were hailstorms, urban growth that puts more analyzed for size, density, compressive compared to the compressive strength of structures at risk, larger structures that strength (Fo), and compressive stress ( c) 585 iceballs, and their mathematical rela- have larger roofs, more expensive repairs by the Insurance Institute of Business tionship was developed for size bins ½ due to higher materials and labor cost, and and Home Safety (IBHS). These data wereσ though 2½ inches in ¼-in. increments. The increased public awareness of the insureds’ analyzed with a variety of methods, and measurement systems and testing environ- rights and responsibilities under the terms analysis shows a clear trend in the increase ment were carefully controlled and similar of their policies. of compressive strength and compressive to the systems used by IBHS in collecting This article addresses the issue of dam- strength uniformity with increases in hail their data. The data collections system aging hail events and specifically address- diameter by size bin. In addition, data were (caliper measurement) was supplemented es the compressive strength of hail. Hail considered by hail size bins, beginning with with a liquid displacement (Archimedes impacts have typically been related to the ½ through 2½ inches in ¼-in. group bins. method) for computing volume, density, and size of the hailstones. Some investigators These data (Fo and c) were regressed with cross-sectional area. These measurements computed the kinetic energy of hail impacts an exponential equation with R2 = 0.97 are also used to compute the compressive σ and adjusted the hail’s falling speed by the and 0.95, respectively. The data show that stress ( c). σ 24 • RCI I NTE R FA C E J ANUA R Y 2 0 1 9 Of fundamental significance is the fact calculation requires vector analysis that tol grip clamp with attached load cell to that the IBHS hailstones were modeled after accounts for both direction and magnitude to measure hailstone compressive strength. oblate spheroids, where the iceballs, cast resolve the KE into direct and shear forces. Measurements showed hail compressive in plastic molds, are near-perfect spheres. strength ranged from as low as 0.19 to as The cross-sectional areas of the two shapes HISTORY OF HAIL COMPRESSIVE high as 490.64 lbf. The temperature was were computed. A uniaxial compressive STRENGTH TESTING not reported. force was used to measure the Fo of iceballs Early work on hail compressive strength Butkovich (1958) used a Brinell hard- with a hydropneumatics press, whereas focused on hailstone air content. Several ness tester to measure the hardness of the IBHS used a hand-operated modified com- researchers, including Browning (1968), List surface of single ice crystals. These data pression clamp. The testing environment (1972 and 1973), Knight (1970, 1974, 1978, showed that the Brinell hardness number temperature was a constant 28°F (-2°C), 1983, and 2001), and Heymsfield (1983, varied by temperature by more than 300% and iceballs were made from distilled water 2014a, and 2014b) investigated air content of in the temperature range from -15°C to and were refrigerated to -16°F (-27°C) for 24 hailstones and their falling behavior. Fewer -50°C (in other words, the colder the tem- hours prior to testing. researchers have investigated the compres- perature, the harder the ice crystals). sive strength of hail. Of the 316 references Note that Brinell’s tests were done on INTRODUCTION used in this work, only 15 (less than 5%) the surface; therefore, hardness would Traditionally, hail is evaluated based discussed the compressive strength of hail, be an appropriate term to describe their upon size; however, size alone does not tell five dealt with strain rates of ice cylinders results. Earlier work by Barnes (1928), the whole story. Some roof and building that were not hailstones at all, and only Moor (1940), and Blackwelder (1940) mea- envelope investigators compute hail’s kinet- three (<1%) papers specifically addressed sured the scratch hardness of the surface of ic energy (KE) (Equation 1) that considers the compressive strength of hailstones. ice crystals using the Moh’s hardness scale. both the hail weight and falling speed. The term “hardness” typically refers to a The obvious difference between the work surface condition and not the entire struc- from Giammanco and Butkovich, Barnes, 1. KE = ½ m V2 ture. The verbiage used to describe hail has Moor, and Blackwelder is that the last four been confusing. In terms of c, we use the researchers only tested the surface condi- Where: Fo divided by the cross-sectional area of the tions of hailstones and not the compressive KE = Kinetic energy (lbf or Joules) average diameter. This is theσ reported in strength of the entire stone. m = mass of the hailstone (lb. or kg) most materials testing literature in stress/ Only the work by Giammanco et al. V = Velocity of the falling hailstone at strain relationships. Strain ( ) isσ the distance (2015) addresses the compressive strength impact (mph or m/s) by which the sample is compressed by c. of the whole hailstone. For the work to be Many hailstones are εdamaged upon specific to what causes hailstones to dam- Some investigators have observed that impact. In short, the investigator mustσ be age roofs and other elements of building hailstorms frequently occur with wind that on the spot and prepared to perform the envelopes, the whole stone must be consid- will affect the falling speed and, thus, KE. investigation before the hail has changed ered, not just its surface condition. Wind causes the speed a hailstone is falling from its impact condition. Even in vehicles Most hail impact testing is done using at to increase (Equation 2) and will increase equipped with computers and radar soft- iceballs. Many building envelope products KE (ASTM E822-92). Since the KE velocity ware, it is not easy to get to the right spot are not even tested with iceballs, with term is squared, increased KE due to veloc- at the right time. Often, ideal locations for investigators opting for ASTM D3746, FM ity is exponential, making KE sensitive to a hail collection are off paved roads that 4470, or UL 2218—all of which rely upon changes in velocity. are not accessible to storm chase vehi- steel balls or steel missiles impacting build- cles—especially ones pulling a mobile lab. ing envelope materials. Steel projectiles 2. FS = √TV2+WS2 The research mobile lab operates at 28°F, do not accurately represent ice due to the and samples are refrigerated until tested. difference in surface hardness and terminal Where: Hailstone temperature is the first item velocity of the different materials. Steel balls FS = Failing speed of hailstone at time measured, and testing is done as soon after are denser than ice and are more uniform; of impact = V collection as safely possible. Samples stored they do not replicate the types of damage TV = Terminal velocity of hailstone at for long will change from their antecedent caused by hailstones. Iceballs are not the time of impact (mph or m/s) condition. Most commercial freezer units same as natural hailstones; they are similar WS = Wind speed during the hail event will produce temperatures between -24 and in surface hardness and terminal velocity, (mph or m/s) -4°F. Compressive strength of ice increases but typically denser with higher Fo. dramatically as the temperature decreases ASTM E822-92 states “no direct rela- Since KE is sensitive to changes in veloc- from -10 to -50°C (14 to -58°F). Ice sur- tionship has been established between the ity, it is necessary to understand how fast face hardness can increase 240% from a effect of impact of iceballs and hailstones.” hail is moving at the time of impact. Hail temperature of 0 to -80°C (32 to -112°F) (UL 2218 contains similar language.) This falling speed is affected by many conditions, (Chaplin, 2016). This work requires the paper offers such a relationship that will including terminal velocity and wind speed. investigator to take the lab to the field. allow new insights into how hail impacts Wind speed also affects the angle the hail is Chasing storms is neither easy nor cheap building envelope products and other mate- falling. Hail KE must be resolved into direct and has numerous risks. rials. This will allow manufacturers a direct and shear energy at impact. This energy Giammanco et al. (2015) used a pis- comparison of iceball testing to natural J ANUA R Y 2 0 1 9 R C I I NTE R FA C E • 2 5 hailstones—something that no “steel ball” FRACTURE MECHANICS own separate set of axes that are randomly test can do.
Load more

Recommended publications
  • Avoiding Slush for Hot-Point Drilling of Glacier Boreholes
    Annals of Glaciology Avoiding slush for hot-point drilling of glacier boreholes Benjamin H. Hills1,2 , Dale P. Winebrenner1,2 , W. T. Elam1,2 and Paul M. S. Kintner1,2 Letter 1Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA and 2Polar Science Center, Cite this article: Hills BH, Winebrenner DP, Applied Physics Laboratory, University of Washington, Seattle, WA, USA Elam WT, Kintner PMS (2021). Avoiding slush for hot-point drilling of glacier boreholes. Abstract Annals of Glaciology 62(84), 166–170. https:// doi.org/10.1017/aog.2020.70 Water-filled boreholes in cold ice refreeze in hours to days, and prior attempts to keep them open with antifreeze resulted in a plug of slush effectively freezing the hole even faster. Thus, antifreeze Received: 12 May 2020 as a method to stabilize hot-water boreholes has largely been abandoned. In the hot-point drilling Revised: 7 September 2020 Accepted: 9 September 2020 case, no external water is added to the hole during drilling, so earlier antifreeze injection is pos- First published online: 12 October 2020 sible while the drill continues melting downward. Here, we use a cylindrical Stefan model to explore slush formation within the parameter space representative of hot-point drilling. We Key words: find that earlier injection timing creates an opportunity to avoid slush entirely by injecting suf- Ice drilling; Ice engineering; Ice temperature; Recrystallization ficient antifreeze to dissolve the hole past the drilled radius. As in the case of hot-water drilling, the alternative is to force mixing in the hole after antifreeze injection to ensure that ice refreezes Author for correspondence: onto the borehole wall instead of within the solution as slush.
    [Show full text]
  • Ice Ic” Werner F
    Extent and relevance of stacking disorder in “ice Ic” Werner F. Kuhsa,1, Christian Sippela,b, Andrzej Falentya, and Thomas C. Hansenb aGeoZentrumGöttingen Abteilung Kristallographie (GZG Abt. Kristallographie), Universität Göttingen, 37077 Göttingen, Germany; and bInstitut Laue-Langevin, 38000 Grenoble, France Edited by Russell J. Hemley, Carnegie Institution of Washington, Washington, DC, and approved November 15, 2012 (received for review June 16, 2012) “ ” “ ” A solid water phase commonly known as cubic ice or ice Ic is perfectly cubic ice Ic, as manifested in the diffraction pattern, in frequently encountered in various transitions between the solid, terms of stacking faults. Other authors took up the idea and liquid, and gaseous phases of the water substance. It may form, attempted to quantify the stacking disorder (7, 8). The most e.g., by water freezing or vapor deposition in the Earth’s atmo- general approach to stacking disorder so far has been proposed by sphere or in extraterrestrial environments, and plays a central role Hansen et al. (9, 10), who defined hexagonal (H) and cubic in various cryopreservation techniques; its formation is observed stacking (K) and considered interactions beyond next-nearest over a wide temperature range from about 120 K up to the melt- H-orK sequences. We shall discuss which interaction range ing point of ice. There was multiple and compelling evidence in the needs to be considered for a proper description of the various past that this phase is not truly cubic but composed of disordered forms of “ice Ic” encountered. cubic and hexagonal stacking sequences. The complexity of the König identified what he called cubic ice 70 y ago (11) by stacking disorder, however, appears to have been largely over- condensing water vapor to a cold support in the electron mi- looked in most of the literature.
    [Show full text]
  • A Primer on Ice
    A Primer on Ice L. Ridgway Scott University of Chicago Release 0.3 DO NOT DISTRIBUTE February 22, 2012 Contents 1 Introduction to ice 1 1.1 Lattices in R3 ....................................... 2 1.2 Crystals in R3 ....................................... 3 1.3 Comparingcrystals ............................... ..... 4 1.3.1 Quotientgraph ................................. 4 1.3.2 Radialdistributionfunction . ....... 5 1.3.3 Localgraphstructure. .... 6 2 Ice I structures 9 2.1 IceIh........................................... 9 2.2 IceIc........................................... 12 2.3 SecondviewoftheIccrystalstructure . .......... 14 2.4 AlternatingIh/Iclayeredstructures . ........... 16 3 Ice II structure 17 Draft: February 22, 2012, do not distribute i CONTENTS CONTENTS Draft: February 22, 2012, do not distribute ii Chapter 1 Introduction to ice Water forms many different crystal structures in its solid form. These provide insight into the potential structures of ice even in its liquid phase, and they can be used to calibrate pair potentials used for simulation of water [9, 14, 15]. In crowded biological environments, water may behave more like ice that bulk water. The different ice structures have different dielectric properties [16]. There are many crystal structures of ice that are topologically tetrahedral [1], that is, each water molecule makes four hydrogen bonds with other water molecules, even though the basic structure of water is trigonal [3]. Two of these crystal structures (Ih and Ic) are based on the same exact local tetrahedral structure, as shown in Figure 1.1. Thus a subtle understanding of structure is required to differentiate them. We refer to the tetrahedral structure depicted in Figure 1.1 as an exact tetrahedral structure. In this case, one water molecule is in the center of a square cube (of side length two), and it is hydrogen bonded to four water molecules at four corners of the cube.
    [Show full text]
  • Arxiv:2004.08465V2 [Cond-Mat.Stat-Mech] 11 May 2020
    Phase equilibrium of liquid water and hexagonal ice from enhanced sampling molecular dynamics simulations Pablo M. Piaggi1 and Roberto Car2 1)Department of Chemistry, Princeton University, Princeton, NJ 08544, USA a) 2)Department of Chemistry and Department of Physics, Princeton University, Princeton, NJ 08544, USA (Dated: 13 May 2020) We study the phase equilibrium between liquid water and ice Ih modeled by the TIP4P/Ice interatomic potential using enhanced sampling molecular dynamics simulations. Our approach is based on the calculation of ice Ih-liquid free energy differences from simulations that visit reversibly both phases. The reversible interconversion is achieved by introducing a static bias potential as a function of an order parameter. The order parameter was tailored to crystallize the hexagonal diamond structure of oxygen in ice Ih. We analyze the effect of the system size on the ice Ih-liquid free energy differences and we obtain a melting temperature of 270 K in the thermodynamic limit. This result is in agreement with estimates from thermodynamic integration (272 K) and coexistence simulations (270 K). Since the order parameter does not include information about the coordinates of the protons, the spontaneously formed solid configurations contain proton disorder as expected for ice Ih. I. INTRODUCTION ture forms in an orientation compatible with the simulation box9. The study of phase equilibria using computer simulations is of central importance to understand the behavior of a given model. However, finding the thermodynamic condition at II. CRYSTAL STRUCTURE OF ICE Ih which two or more phases coexist is particularly hard in the presence of first order phase transitions.
    [Show full text]
  • In the United States District Court for the District of Maine
    Case 2:21-cv-00154-JDL Document 1 Filed 06/14/21 Page 1 of 13 PageID #: 1 IN THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF MAINE ICE CASTLES, LLC, a Utah limited liability company, Plaintiff, COMPLAINT vs. Case No.: ____________ CAMERON CLAN SNACK CO., LLC, a Maine limited liability company; HARBOR ENTERPRISES MARKETING AND JURY TRIAL DEMANDED PRODUCTION, LLC, a Maine limited liability company; and LESTER SPEAR, an individual, Defendants. Plaintiff Ice Castles, LLC (“Ice Castles”), by and through undersigned counsel of record, hereby complains against Defendants Cameron Clan Snack Co., LLC; Harbor Enterprises Marketing and Production, LLC; and Lester Spear (collectively, the “Defendants”) as follows: PARTIES 1. Ice Castles is a Utah limited liability company located at 1054 East 300 North, American Fork, Utah 84003. 2. Upon information and belief, Defendant Cameron Clan Snack Co., LLC is a Maine limited liability company with its principal place of business at 798 Wiscasset Road, Boothbay, Maine 04537. 3. Upon information and belief, Defendant Harbor Enterprises Marketing and Production, LLC is a Maine limited liability company with its principal place of business at 13 Trillium Loop, Wyman, Maine 04982. Case 2:21-cv-00154-JDL Document 1 Filed 06/14/21 Page 2 of 13 PageID #: 2 4. Upon information and belief, Defendant Lester Spear is an individual that resides in Boothbay, Maine. JURISDICTION AND VENUE 5. This is a civil action for patent infringement arising under the Patent Act, 35 U.S.C. § 101 et seq. 6. This Court has subject matter jurisdiction over this controversy pursuant to 28 U.S.C.
    [Show full text]
  • A Hail Size Distribution Impact Transducer
    A Hail Size Distribution Impact Transducer John E. Lanea, Robert C. Youngquistb, William D. Haskella, and Robert B. Coxa aASRC Aerospace Corporation, P.O. Box 21087, Kennedy Space Center, FL 32815 [email protected] [email protected] [email protected] bNational Aeronautics and Space Administration (NASA), Kennedy Space Center, FL 32899 [email protected] Abstract: An active impact transducer has been designed and tested for the purpose of monitor- ing hail fall in the vicinity of the Space Shuttle launch pads. An important outcome of this design is the opportunity to utilize frequency analysis to discriminate between the audio signal generat- ed from raindrop impacts and that of hailstone impacts. The sound of hail impacting a metal plate is subtly but distinctly different than the sound of rain impacts. This useful characteristic permits application of signal processing algorithms that are inherently more robust than tech- niques relying on amplitude processing alone in the implementation of a hail disdrometer. 1 1. Introduction Impact disdrometers have long been a useful meteorological tool to measure and quantify rainfall drop size distributions, where a drop momentum is converted into a single electrical im- pulse.1,2 The electrical impulse amplitude is converted to an estimate of drop diameter by means of an empirical calibration formula. The calibration may be a one-time procedure involving dropping numerous known-size-calibration drops from a tower of sufficient height to achieve terminal velocity. The test drop sizes must adequately span the size range of interest. Alternative- ly, or as a supplement to the single drop calibration, an in situ method of comparing the sum of accumulated drop impulses to the tip time interval of a tipping-bucket rain gauge may be uti- lized.3 Prior to launch, the Space Shuttle and other NASA launch vehicles are primarily large ther- mos bottles containing substantial quantities of cryogenic fuels.
    [Show full text]
  • ICE COVERED LAKES Ice Formation Thermal Regime
    I ICE COVERED LAKES Ice formed from the underside of the ice sheet has crys- tals with columnar structure; it is possible to see through the ice. Such ice is called black ice. Ice can also be formed Lars Bengtsson in a slush layer between the snow and the top of the ice. Department of Water Resources Engineering, When the weight of the snow is more than the lifting force Lund University, Lund, Sweden from the ice, the ice cover is forced under the water surface and water enters into the snow which becomes saturated Ice formation with water. When this slush layer freezes, snow ice or Lakes at high latitudes or high altitudes are ice covered white ice is formed. The crystals in this kind of ice are ran- part of the year; typically from November to April and in domly distributed. This ice is not transparent but looks the very north sometimes from October to early June. Arc- somewhat like milk. An example of ice growth is shown tic lakes may be ice covered throughout the year. When in Figure 1 from a bay in the Luleå archipelago (almost there is a regular ice cover for several months, the ice fresh water). thickness reaches more than ½ meter. At mid latitudes The ice on a lake has ecological consequences. Since occasional ice cover may appear for short periods several there is no exchange with the atmosphere, the oxygen con- times during a winter. Where there is a stable ice cover, tent of the water decreases and the bottom layers may be ice roads are prepared.
    [Show full text]
  • Guidelines for Safe Ice Construction
    GUIDELINES FOR SAFE ICE CONSTRUCTION 2015 GUIDELINES FOR SAFE ICE CONSTRUCTION Department of Transportation February 2015 This document is produced by the Department of Transportation of the Government of the Northwest Territories. It is published in booklet form to provide a comprehensive and easy to carry reference for field staff involved in the construction and maintenance of winter roads, ice roads, and ice bridges. The bearing capacity guidance contained within is not appropriate to be used for stationary loads on ice covers (e.g. drill pads, semi-permanent structures). The Department of Transportation would like to acknowledge NOR-EX Ice Engineering Inc. for their assistance in preparing this guide. Table of Contents 1.0 INTRODUCTION .................................................5 2.0 DEFINITIONS ....................................................8 3.0 ICE BEHAVIOR UNDER LOADING ................................13 4.0 HAZARDS AND HAZARD CONTROLS ............................17 5.0 DETERMINING SAFE ICE BEARING CAPACITY .................... 28 6.0 ICE COVER MANAGEMENT ..................................... 35 7.0 END OF SEASON GUIDELINES. 41 Appendices Appendix A Gold’s Formula A=4 Load Charts Appendix B Gold’s Formula A=5 Load Charts Appendix C Gold’s Formula A=6 Load Charts The following Appendices can be found online at www.dot.gov.nt.ca Appendix D Safety Act Excerpt Appendix E Guidelines for Working in a Cold Environment Appendix F Worker Safety Guidelines Appendix G Training Guidelines Appendix H Safe Work Procedure – Initial Ice Measurements Appendix I Safe Work Procedure – Initial Snow Clearing Appendix J Ice Cover Inspection Form Appendix K Accident Reporting Appendix L Winter Road Closing Protocol (March 2014) Appendix M GPR Information Tables 1. Modification of Ice Loading and Remedial Action for various types of cracks .........................................................17 2.
    [Show full text]
  • Best Practices for Building and Working Safely on Ice Covers in Ontario
    Best Practices for Building and Working Safely on Ice Covers in Ontario ihsa.ca IHSA has additional information on this and other topics. Visit ihsa.ca or call Customer Service at 1-800-263-5024 The contents of this publication are for general information only. This publication should not be regarded or relied upon as a definitive guide to government regulations or to safety practices and procedures. The contents of this publication were, to the best of our knowledge, current at the time of printing. However, no representations of any kind are made with regard to the accuracy, completeness, or sufficiency of the contents. The appropriate regulations and statutes should be consulted. In case of any inconsistency between this document and the Occupational Health and Safety Act or associated regulations, the legislation will always prevail. Readers should not act on the information contained herein without seeking specific independent legal advice on their specific circumstance. The Infrastructure Health & Safety Association is pleased to answer individual requests for counselling and advice. The basis for this document is the 2013 version of the Government of Alberta’s Best Practices for Building and Working Safely on Ice Covers in Alberta. The content has been used with permission from the Government of Alberta. This document is dedicated to the nearly 500 people in Canada who have lost their lives over the past 10 years while crossing or working on floating ice. Over the period of 1991 to 2000, there were 447 deaths associated with activities on ice. Of these, 246 involved snowmobiles, 150 involved non-motorized activity, and 51 involved motorized vehicles.
    [Show full text]
  • Modeling the Ice VI to VII Phase Transition
    Modeling the Ice VI to VII Phase Transition Dawn M. King 2009 NSF/REU PROJECT Physics Department University of Notre Dame Advisor: Dr. Kathie E. Newman July 31, 2009 Abstract Ice (solid water) is found in a number of different structures as a function of temperature and pressure. This project focuses on two forms: Ice VI (space group P 42=nmc) and Ice VII (space group Pn3m). An interesting feature of the structural phase transition from VI to VII is that both structures are \self clathrate," which means that each structure has two sublattices which interpenetrate each other but do not directly bond with each other. The goal is to understand the mechanism behind the phase transition; that is, is there a way these structures distort to become the other, or does the transition occur through the breaking of bonds followed by a migration of the water molecules to the new positions? In this project we model the transition first utilizing three dimensional visualization of each structure, then we mathematically develop a common coordinate system for the two structures. The last step will be to create a phenomenological Ising-like spin model of the system to capture the energetics of the transition. It is hoped the spin model can eventually be studied using either molecular dynamics or Monte Carlo simulations. 1 Overview of Ice The known existence of many solid states of water provides insight into the complexity of condensed matter in the universe. The familiarity of ice and the existence of many structures deem ice to be interesting in the development of techniques to understand phase transitions.
    [Show full text]
  • 11Th International Conference on the Physics and Chemistry of Ice, PCI
    11th International Conference on the Physics and Chemistry of Ice (PCI-2006) Bremerhaven, Germany, 23-28 July 2006 Abstracts _______________________________________________ Edited by Frank Wilhelms and Werner F. Kuhs Ber. Polarforsch. Meeresforsch. 549 (2007) ISSN 1618-3193 Frank Wilhelms, Alfred-Wegener-Institut für Polar- und Meeresforschung, Columbusstrasse, D-27568 Bremerhaven, Germany Werner F. Kuhs, Universität Göttingen, GZG, Abt. Kristallographie Goldschmidtstr. 1, D-37077 Göttingen, Germany Preface The 11th International Conference on the Physics and Chemistry of Ice (PCI- 2006) took place in Bremerhaven, Germany, 23-28 July 2006. It was jointly organized by the University of Göttingen and the Alfred-Wegener-Institute (AWI), the main German institution for polar research. The attendance was higher than ever with 157 scientists from 20 nations highlighting the ever increasing interest in the various frozen forms of water. As the preceding conferences PCI-2006 was organized under the auspices of an International Scientific Committee. This committee was led for many years by John W. Glen and is chaired since 2002 by Stephen H. Kirby. Professor John W. Glen was honoured during PCI-2006 for his seminal contributions to the field of ice physics and his four decades of dedicated leadership of the International Conferences on the Physics and Chemistry of Ice. The members of the International Scientific Committee preparing PCI-2006 were J.Paul Devlin, John W. Glen, Takeo Hondoh, Stephen H. Kirby, Werner F. Kuhs, Norikazu Maeno, Victor F. Petrenko, Patricia L.M. Plummer, and John S. Tse; the final program was the responsibility of Werner F. Kuhs. The oral presentations were given in the premises of the Deutsches Schiffahrtsmuseum (DSM) a few meters away from the Alfred-Wegener-Institute.
    [Show full text]
  • 2Growth, Structure and Properties of Sea
    Growth, Structure and Properties 2 of Sea Ice Chris Petrich and Hajo Eicken 2.1 Introduction The substantial reduction in summer Arctic sea ice extent observed in 2007 and 2008 and its potential ecological and geopolitical impacts generated a lot of attention by the media and the general public. The remote-sensing data documenting such recent changes in ice coverage are collected at coarse spatial scales (Chapter 6) and typically cannot resolve details fi ner than about 10 km in lateral extent. However, many of the processes that make sea ice such an important aspect of the polar oceans occur at much smaller scales, ranging from the submillimetre to the metre scale. An understanding of how large-scale behaviour of sea ice monitored by satellite relates to and depends on the processes driving ice growth and decay requires an understanding of the evolution of ice structure and properties at these fi ner scales, and is the subject of this chapter. As demonstrated by many chapters in this book, the macroscopic properties of sea ice are often of most interest in studies of the interaction between sea ice and its environment. They are defi ned as the continuum properties averaged over a specifi c volume (Representative Elementary Volume) or mass of sea ice. The macroscopic properties are determined by the microscopic structure of the ice, i.e. the distribution, size and morphology of ice crystals and inclusions. The challenge is to see both the forest, i.e. the role of sea ice in the environment, and the trees, i.e. the way in which the constituents of sea ice control key properties and processes.
    [Show full text]