A Water Activity Based Model of Heterogeneous Ice Nucleation Kinetics for Freezing of Water and Aqueous Solution Droplets PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download A Water Activity Based Model of Heterogeneous Ice Nucleation Kinetics for Freezing of Water and Aqueous Solution Droplets PDF full book. Access full book title A Water Activity Based Model of Heterogeneous Ice Nucleation Kinetics for Freezing of Water and Aqueous Solution Droplets by . Download full books in PDF and EPUB format.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
Get Book Here
Book Description
Immersion freezing of water and aqueous solutions by particles acting as ice nuclei (IN) is a common process of heterogeneous ice nucleation which occurs in many environments, especially in the atmosphere where it results in the glaciation of clouds. Here we experimentally show, using a variety of IN types suspended in various aqueous solutions, that immersion freezing temperatures and kinetics can be described solely by temperature, T, and solution water activity, aw, which is the ratio of the vapour pressure of the solution and the saturation water vapour pressure under the same conditions and, in equilibrium, equivalent to relative humidity (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, Jhet, to be uniquely expressed by T and aw, a result we term the aw based immersion freezing model (ABIFM). This method is independent of the nature of the solute and accounts for several varying parameters, including cooling rate and IN surface area, while providing a holistic description of immersion freezing and allowing prediction of freezing temperatures, Jhet, frozen fractions, ice particle production rates and numbers. Our findings are based on experimental freezing data collected for various IN surface areas, A, and cooling rates, r, of droplets variously containing marine biogenic material, two soil humic acids, four mineral dusts, and one organic monolayer acting as IN. For all investigated IN types we demonstrate that droplet freezing temperatures increase as A increases. Similarly, droplet freezing temperatures increase as the cooling rate decreases. The log10(Jhet) values for the various IN types derived exclusively by T and aw, provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total particulate surface area, and cloud activation timescales typical of atmospheric conditions. Finally, we demonstrate that ABIFM can be used to derive frozen fractions of droplets and ice particle production for atmospheric models of cirrus and mixed phase cloud conditions.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
Get Book Here
Book Description
Immersion freezing of water and aqueous solutions by particles acting as ice nuclei (IN) is a common process of heterogeneous ice nucleation which occurs in many environments, especially in the atmosphere where it results in the glaciation of clouds. Here we experimentally show, using a variety of IN types suspended in various aqueous solutions, that immersion freezing temperatures and kinetics can be described solely by temperature, T, and solution water activity, aw, which is the ratio of the vapour pressure of the solution and the saturation water vapour pressure under the same conditions and, in equilibrium, equivalent to relative humidity (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, Jhet, to be uniquely expressed by T and aw, a result we term the aw based immersion freezing model (ABIFM). This method is independent of the nature of the solute and accounts for several varying parameters, including cooling rate and IN surface area, while providing a holistic description of immersion freezing and allowing prediction of freezing temperatures, Jhet, frozen fractions, ice particle production rates and numbers. Our findings are based on experimental freezing data collected for various IN surface areas, A, and cooling rates, r, of droplets variously containing marine biogenic material, two soil humic acids, four mineral dusts, and one organic monolayer acting as IN. For all investigated IN types we demonstrate that droplet freezing temperatures increase as A increases. Similarly, droplet freezing temperatures increase as the cooling rate decreases. The log10(Jhet) values for the various IN types derived exclusively by T and aw, provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total particulate surface area, and cloud activation timescales typical of atmospheric conditions. Finally, we demonstrate that ABIFM can be used to derive frozen fractions of droplets and ice particle production for atmospheric models of cirrus and mixed phase cloud conditions.
Author: Hans Ramløv
Publisher: Springer Nature
ISBN: 3030419290
Category : Science
Languages : en
Pages : 318
Get Book Here
Book Description
This first volume provides a comprehensive overview on evolutionary, environmental and systematic aspects of antifreeze proteins. It shortly explains the physical properties of ice and further intelligibly describes the biology of the antifreeze proteins in different organisms, and offers a detailed insight into their history of evolution. In addition the book discusses the status of the current knowledge and ongoing research and highlights also those parts, where further investigation needs to be done. Together with the second volume on the biochemistry and molecular biology of antifreeze proteins, this book represents a unique, comprehensive work and a must-have for students and scientists in biochemistry, evolution, physiology and physical chemistry.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
Get Book Here
Book Description
Immersion freezing of water and aqueous (NH4)2SO4 droplets containing leonardite (LEO) and Pahokee peat (PP) serving as surrogates for humic-like substances (HULIS) has been investigated. Organic aerosol containing HULIS are ubiquitous in the atmosphere; however, their potential for ice cloud formation is uncertain. Immersion freezing has been studied for temperatures as low as 215K and solution water activity, aw, from 0.85 to 1.0. The freezing temperatures of water and aqueous solution droplets containing LEO and PP are 5-15 K warmer than homogeneous ice nucleation temperatures. Heterogeneous freezing temperatures can be represented by a horizontal shift of the ice melting curve as a function of solution aw by [Delta]aw = 0.2703 and 0.2466, respectively. Corresponding heterogeneous ice nucleation rate coefficients, Jhet, are (9.6 ± 2.5) × 104 and (5.4 ± 1.4) × 104 cm-2 s-1 for LEO and PP containing droplets, respectively, and remain constant along freezing curves characterized by [Delta]aw. Consequently predictions of freezing temperatures and kinetics can be made without knowledge of the solute type when relative humidity and ice nuclei (IN) surface areas are known. The acquired ice nucleation data are applied to evaluate different approaches to fit and reproduce experimentally derived frozen fractions. In addition, we apply a basic formulation of classical nucleation theory ([alpha](T)-model) to calculate contact angles and frozen fractions. Contact angles calculated for each ice nucleus as a function of temperature, [alpha](T)-model, reproduce exactly experimentally derived frozen fractions without involving free-fit parameters. However, assigning the IN a single contact angle for the entire population (single-[alpha] model) is not suited to represent the frozen fractions. Application of [alpha]-PDF, active sites, and deterministic model approaches to measured frozen fractions yield similar good representations. Furthermore, when using a single parameterization of [alpha]-PDF or active sites distribution to fit all individual aw immersion freezing data simultaneously, frozen fraction curves are not reproduced. This implies that these fitting formulations cannot be applied to immersion freezing of aqueous solutions, and suggests that derived fit parameters do not represent independent particle properties. Thus, from fitting frozen fractions only, the underlying ice nucleation mechanism and nature of the ice nucleating sites cannot be inferred. In contrast to using fitted functions obtained to represent experimental conditions only, we suggest to use experimentally derived Jhet as a function of temperature and aw that can be applied to conditions outside of those probed in laboratory. Finally, this is because Jhet(T) is independent of time and IN surface areas in contrast to the fit parameters obtained by representation of experimentally derived frozen fractions.
Author: Peter Knippertz
Publisher: Springer
ISBN: 9401789789
Category : Science
Languages : en
Pages : 526
Get Book Here
Book Description
This volume presents state-of-the-art research about mineral dust, including results from field campaigns, satellite observations, laboratory studies, computer modelling and theoretical studies. Dust research is a new, dynamic and fast-growing area of science and due to its multiple roles in the Earth system, dust has become a fascinating topic for many scientific disciplines. Aspects of dust research covered in this book reach from timescales of minutes (as with dust devils, cloud processes and radiation) to millennia (as with loess formation and oceanic sediments), making dust both a player and recorder of environmental change. The book is structured in four main parts that explore characteristics of dust, the global dust cycle, impacts of dust on the Earth system, and dust as a climate indicator. The chapters in these parts provide a comprehensive, detailed overview of this highly interdisciplinary subject. The contributions presented here cover dust from source to sink and describe all the processes dust particles undergo while travelling through the atmosphere. Chapters explore how dust is lifted and transported, how it affects radiation, clouds, regional circulations, precipitation and chemical processes in the atmosphere and how it deteriorates air quality. The book explores how dust is removed from the atmosphere by gravitational settling, turbulence or precipitation, how iron contained in dust fertilizes terrestrial and marine ecosystems, and about the role that dust plays in human health. We learn how dust is observed, simulated using computer models and forecast. The book also details the role of dust deposits for climate reconstructions. Scientific observations and results are presented, along with numerous illustrations. This work has an interdisciplinary appeal and will engage scholars in geology, geography, chemistry, meteorology and physics, amongst others with an interest in the Earth system and environmental change. body>
Author: Yue Zhang
Publisher: American Chemical Society
ISBN: 0841299293
Category : Science
Languages : en
Pages : 176
Get Book Here
Book Description
The uncertainties in the aerosol effects on radiative forcing limit our knowledge of climate change, presenting us with an important research challenge. Aerosols in Atmospheric Chemistry introduces basic concepts about the characterization, formation, and impacts of ambient aerosol particles as an introduction to graduate students new to the field. Each chapter also provides an up-to-date synopsis of the latest knowledge of aerosol particles in atmospheric chemistry.
Author: Helmut Baumgärtel
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 348684380X
Category : Science
Languages : en
Pages : 292
Get Book Here
Book Description
‹";Progress in Physical Chemistry"; is a collection of recent ";Review Articles"; published in the ";Zeitschrift für Physikalische Chemie";. The aim of a ";Review Article"; is to give a profound survey on a special topic outlining the history, development, state of the art and future research. Collecting these Reviews the Editor(s) of Zeitschrift für Physikalische Chemie intend to counteract the expanding flood of papers and thereby to give students and researchers a means to obtain fundamental knowledge on their special interests. The first volume of Progress in Physical Chemistry is mainly focussed on intermolecular interaction, also glancing at topics that are marginally touched. Contents •Martina Havenith*, Gerhard W. Schwaab, Attacking a Small Beast: Ar-Co, a Proto-type for Intermolecular Forces •Otto Dopfer, IR Spectroscopy of Microsolvated Aromatic Cluster Ions: Ionization-Induced Switch in Aromatic Molecule-Solvent Recognition •Clemens F. Kaminski, Fluorescence Imaging of Reactive Processes •T. Stangler, R. Hartmann, D.Willbold, B.W. König*, Modern high resolution NMR fort he study of structure, dynamics and interactions of biological macromolecules •Markus Drescher, Time-Resolved ESCA: a Novel Probe for Chemical Dynamics •Constanze Donner, Kinetics of Electrochemical Phase Formation in Two-Dimensional Systems •Claus Czeslik, Factors Ruling Protein Adsorption •Thomas Koop, Homogeneous Ice Nucleation in Water and Aqueous Solutions.
Author: Vitaly I. Khvorostyanov
Publisher: Cambridge University Press
ISBN: 1107016037
Category : Science
Languages : en
Pages : 801
Get Book Here
Book Description
This book advances understanding of cloud microphysics and provides a unified theoretical foundation for modeling cloud processes, for researchers and advanced students.
Author: Danièle Clausse
Publisher: Bentham Science Publishers
ISBN: 168108130X
Category : Science
Languages : en
Pages : 300
Get Book Here
Book Description
Emulsions (simple, mixed or multiple) are essentially pure substances, aqueous or organic binary solutions. The have a wide range of uses, including industrial cooling and heat transfer processes. This monograph gives a brief overview of supercooling, crystallization and melting processes within emulsions. Differential scanning calorimetrey (DSC) coupled with RX is the main technique used to demonstrate these processes. Temperature readings in this work have been defined taking into account known nucleation laws. These results have been used to show mass transfers occurring within mixed emulsions (solid ripening) or multiple emulsions (composition ripening), gas hydrate formation due to a chemical reaction between water and a diffuse specific compound, these phenomena being described by diffusive models. Other aspects of heat transfer process covered in this book include the latent energy released at crystallizations or absorbed at the melting (which alters the temperature field through emulsions), the kinetics of phase transformations and self-regulation of temperature in nodules containing phase changing materials. This monograph is intended for advanced chemistry graduates as well as industrial and chemical engineers working with cooling and heat transfer systems.
Author: Yangang Liu
Publisher: John Wiley & Sons
ISBN: 1119528941
Category : Science
Languages : en
Pages : 483
Get Book Here
Book Description
Improving weather and climate prediction with better representation of fast processes in atmospheric models Many atmospheric processes that influence Earth’s weather and climate occur at spatiotemporal scales that are too small to be resolved in large scale models. They must be parameterized, which means approximately representing them by variables that can be resolved by model grids. Fast Processes in Large-Scale Atmospheric Models: Progress, Challenges and Opportunities explores ways to better investigate and represent multiple parameterized processes in models and thus improve their ability to make accurate climate and weather predictions. Volume highlights include: Historical development of the parameterization of fast processes in numerical models Different types of major sub-grid processes and their parameterizations Efforts to unify the treatment of individual processes and their interactions Top-down versus bottom-up approaches across multiple scales Measurement techniques, observational studies, and frameworks for model evaluation Emerging challenges, new opportunities, and future research directions The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
Author: George R. Wood
Publisher:
ISBN:
Category : Electrolyte solutions
Languages : en
Pages : 188
Get Book Here
Book Description
