Author: Bernd R. PinzerPublisher:
ISBN:
Category :
Languages : en
Pages : 148
Book Description
Dynamics of Temperature Gradient Snow Metamorphism
Author: Bernd R. PinzerDynamics of Snow and Ice Masses
Author: Samuel C. ColbeckPublisher: Elsevier
ISBN: 0323148891
Category : Science
Languages : en
Pages : 479
Book Description
Dynamics of Snow and Ice Masses gives an outline of snow and ice studies with an emphasis on essential properties and processes. The monograph also treats the dynamical aspects of snow and ice masses. The text covers topics such as the flow and temperature of ice sheets and shelves, the numerical modeling of ice-sheet changes; the structure of glaciers, the experimental creep behavior of ice, flow law of glacier ice, and advance and retreat of glaciers. Also covered are topics such as sea ice - the physics of its growth, drift, and decay; iceberg deterioration, sources, drift, and drift patterns; and freshwater ice growth, motion, and decay. The book is recommended as a textbook for graduate-level students of snow and ice studies and as reference for climatologists.
The Effects of Overburden and Temperature Gradients on Dry Snow Metamorphism
Author: Xuan WangPublisher:
ISBN:
Category :
Languages : en
Pages : 242
Book Description
Investigation of snow properties can be applied to understand a range of issues including climate change and snow avalanche prediction. Most of the snow properties, i.e. thermal and mechanical, are directly linked to the microstructure of snowpack and those properties evolve simultaneously with deformation of the snow and its metamorphism. Thus, this dissertation primarily explores the characterization of snow microstructural evolution under the effects of temperature gradient and overburden. Snow structural evolution was monitored by the techniques of scanning electron microscopy (SEM), X-ray computed microtomography (micro-CT) and numerical simulation. The temperature gradient setup constructed for this work, commercial compression stage and commercial cooling stage were used to simulate the natural boundary conditions within snow layers. Of the different types of metamorphism that may occur in snow layers, temperature gradient metamorphism (TGM) is perhaps the most significant one. The snow layer undergoing TGM will lose its strength and transform into a weak layer, which is the microstructural cause of avalanches. 1-D arrays of ice spheres were used as a reproducable approach to observe snow microstructural evolution and investigate the mass transfer process. By controlling temperatures on both sides of ice spheres, different vapor transfer directions were studied. Our experiments demonstrated the mass transfer processes and microstructural evolutions under alternating and unidirectional temperature gradient. We also investigated the effects of temperature gradient on natural snow. The specific surface area (SSA) was used to characterize the TGM. The temperature gradient magnitude and the initial snow type both influence the evolution of the SSA. The trend in the SSA is controlled by two mechanisms, grain growth and the formation of complex surfaces. For the relationship between the structure of snow and its mechanical properties, we focused on investigating how the structure of snow evolves under an applied load. Micro-CT images, complemented with SEM images, demonstrate that the mechanical properties of snow depend on the density, the SSA, and bond formation. During our interrupted compression tests, the SSA decreased more rapidly than that determined for snow metamorphism without an overburden. It is clearly evident that pressure sintering of snow contributes to accelerated sintering and coarsening processes.
Temperature Gradient Weakening in Snow
Author: R. A. SommerfeldPublisher:
ISBN:
Category : Depth hoar
Languages : en
Pages : 6
Book Description
An Integrated Microstructural Study of Dry Snow Metamorphism Under Generalized Thermal Conditions
Author: Daniel August MillerPublisher:
ISBN: 9781423510499
Category : Depth hoar
Languages : en
Pages : 261
Book Description
Snow microstructure significantly influences the mechanical, thermal, and electromagnetic properties of snow. The microstructure is constantly evolving from the time it is deposited on the surface until it sublimates or melts. The resulting time variant material properties make the study of snow metamorphism of fundamental importance to a wide variety of snow science disciplines. Dry snow metamorphism has traditionally been classified by the thermal gradient encountered in the snowpack. Snow experiencing a predominantly equi-temperature environment develops different micro structure than snow that is subjected to a temperature gradient. As such, previous research has evaluated snow metamorphism based upon select thermal gradient dependent processes, when in reality, there is a continuum of physical processes simultaneously contributing to metamorphism. In previous research, a discrete temperature gradient transition between the two thermal environments has been used to activate separate morphological analyses. The current research focuses on a unifying approach to dry snow metamorphism that is applicable to generalized thermal environments. The movement of heat and mass is not prescribed, but is allowed to develop naturally through modeling of physical processes. Heat conduction, mass conservation, and phase change equations are derived in a simplified two-dimensional approach. Each differential equation is non-linearly coupled to the others through phase change. The microstructural network is then discretized into elements and nodes. Finite difference equations are developed for the network, and numerically solved using iterative techniques. The finite difference model provides a unique platform to study the influence of numerous geometric and thermodynamic parameters relating to dry snow metamorphism. Numerical metamorphism studies in an equi-temperature environment agree well with established trends and published experimental results.
Fundamentals of Glacier Dynamics, Second Edition
Author: C.J. van der VeenPublisher: CRC Press
ISBN: 1439835667
Category : Science
Languages : en
Pages : 407
Book Description
Measuring, monitoring, and modeling technologies and methods changed the field of glaciology significantly in the 14 years since the publication of the first edition of Fundamentals of Glacier Dynamics. Designed to help readers achieve the basic level of understanding required to describe and model the flow and dynamics of glaciers, this second edition provides a theoretical framework for quantitatively interpreting glacier changes and for developing models of glacier flow. See What’s New in the Second Edition: Streamlined organization focusing on theory, model development, and data interpretation Introductory chapter reviews the most important mathematical tools used throughout the remainder of the book New chapter on fracture mechanics and iceberg calving Consolidated chapter covers applications of the force-budget technique using measurements of surface velocity to locate mechanical controls on glacier flow The latest developments in theory and modeling, including the addition of a discussion of exact time-dependent similarity solutions that can be used for verification of numerical models The book emphasizes developing procedures and presents derivations leading to frequently used equations step by step to allow readers to grasp the mathematical details as well as physical approximations involved without having to consult the original works. As a result, readers will have gained the understanding needed to apply similar techniques to somewhat different applications. Extensively updated with new material and focusing more on presenting the theoretical foundations of glacier flow, the book provides the tools for model validation in the form of analytical steady-state and time-evolving solutions. It provides the necessary background and theoretical foundation for developing more realistic ice-sheet models, which is essential for better integration of data and observations as well as for better model development.
Finite Element Simulation of Temperature Gradient Metamorphism in Dry Snow
Author: Mark ChristonPublisher:
ISBN:
Category : Acid precipitation (Meteorology)
Languages : en
Pages : 113
Book Description
On Metamorphism and Hardening of Snow Under Constant Pressure and Temperature Gradient
Author: Marcel de QuervainA Branch Theory of Temperature Gradient Metamorphism in Snow
Author: R. A. SommerfeldSeasonal Snowcovers: Physics, Chemistry, Hydrology
Author: H.G. JonesPublisher: Springer Science & Business Media
ISBN: 9400939477
Category : Science
Languages : en
Pages : 748
Book Description
In recent years, much concern has been expressed on the deleterious effects that anthropogenic emissions of acidic pollutants have on ecosystems of both industrialized countries and remote areas of the world. In many of these regions, seasonal snowcover is a major factor in the transfer of atmospheric pollutants, either to terrestrial and aquatic ecosystems or to the more permanent reservoirs of glaciers and ice sheets. The recognition of the role that seasonal snowcovers can thus play in the chemical dynamics of whole ecosystems was recently echoed by the Committee on Glaciology of the National Research Council (National Academy of Sciences, National Academy of Engineering and the Institute of Medicine) which recommended that studies on "Impurities in the snowpack, their discharge into runoff, and management of the problem" be rated at the highest prority level (ref. a). It is in this context that the Advanced Research Institute (ASI) brought together scientists active in the fields of snow physics, snow chemistry and snow hydrology. The programme was structured so as to facilitate the exchange of information and ideas on the theories for the chemical evolution of seasonal snowcovers and snowmelt and on the impact of the chemical composition of the meltwaters on the different components of hydrological systems. As a consequence the ASI also attracted participants from potential users of the information that was disseminated; these were particularly concerned with the effects of snowmelt and snowcover on terrestrial biota and those of lakes and streams.