That water can exist in two distinct ‘glassy’ forms — low- and high-density amorphous ice — may provide the key to understanding some of the puzzling characteristics of cold and supercooled water, of which the glassy solids are more-viscous counterparts. Recent experimental and theoretical studies of both liquid and glassy water are now starting to offer the prospect of a coherent picture of the unusual properties of this ubiquitous substance.

https://polymer.bu.edu/hes/articles/ms98.pdf

The relationship between liquid, supercooled and glassy water

The anomalous properties of cold and supercooled water, such as the fact that at sufficiently low temperatures it becomes more compressible and less dense when cooled, and more fluid when compressed, have attracted the attention of physical scientists for a long time. The discovery in the 1970s that several thermodynamic and transport properties of supercooled water exhibit a pronounced temperature dependence and appear to diverge slightly below the homogeneous nucleation temperature inspired a large number of experimental and theoretical studies. Likewise, an important body of work on glassy water has been stimulated by experiments, starting in the mid-1980s and continuing to this date, which suggest that vitreous water can exist in at least two apparently distinct forms. A coherent theory of the thermodynamic and transport properties of supercooled and glassy water does not yet exist. Nevertheless, significant progress towards this goal has been made during the past 20 years. This article summarizes the known experimental facts and reviews critically theoretical and computational work aimed at interpreting the observations and providing a unified viewpoint on cold, non-crystalline, metastable states of water.

https://iopscience.iop.org/article/10.1088/0953-8984/15/45/R01/pdf

Supercooled and glassy water

The formation of ice particles in the Earth's atmosphere strongly affects the properties of clouds and their impact on climate. Despite the importance of ice formation in determining the properties of clouds, the Intergovernmental Panel on Climate Change (IPCC, 2007) was unable to assess the impact of atmospheric ice formation in their most recent report because our basic knowledge is insufficient. Part of the problem is the paucity of quantitative information on the ability of various atmospheric aerosol species to initiate ice formation. Here we review and assess the existing quantitative knowledge of ice nucleation by particles immersed within supercooled water droplets. We introduce aerosol species which have been identified in the past as potentially important ice nuclei and address their ice-nucleating ability when immersed in a supercooled droplet. We focus on mineral dusts, biological species (pollen, bacteria, fungal spores and plankton), carbonaceous combustion products and volcanic ash. In order to make a quantitative comparison we first introduce several ways of describing ice nucleation and then summarise the existing information according to the time-independent (singular) approximation. Using this approximation in combination with typical atmospheric loadings, we estimate the importance of ice nucleation by different aerosol types. According to these estimates we find that ice nucleation below about −15 °C is dominated by soot and mineral dusts. Above this temperature the only materials known to nucleate ice are biological, with quantitative data for other materials absent from the literature. We conclude with a summary of the challenges our community faces.

/pdf/ice-nucleation-by-particles-immersed-in-supercooled-cloud-4c88zmbtg2.pdf

Ice nucleation by particles immersed in supercooled cloud droplets

Water is the most abundant liquid on earth and also the substance with the largest number of anomalies in its properties. It is a prerequisite for life and as such a most important subject of current research in chemical physics and physical chemistry. In spite of its simplicity as a liquid, it has an enormously rich phase diagram where different types of ices, amorphous phases, and anomalies disclose a path that points to unique thermodynamics of its supercooled liquid state that still hides many unraveled secrets. In this review we describe the behavior of water in the regime from ambient conditions to the deeply supercooled region. The review describes simulations and experiments on this anomalous liquid. Several scenarios have been proposed to explain the anomalous properties that become strongly enhanced in the supercooled region. Among those, the second critical-point scenario has been investigated extensively, and at present most experimental evidence point to this scenario. Starting from very low ...

/pdf/water-a-tale-of-two-liquids-hxorql1ud9.pdf

Water: A Tale of Two Liquids

We examine the physical mechanisms governing the formation of snow crystals, treating this problem as a case study of the dynamics of crystal growth from the vapour phase. Particular attention is given to the basic theoretical underpinnings of the subject, especially the interplay of particle diffusion, heat diffusion and surface attachment kinetics during crystal growth, as well as growth instabilities that have important effects on snow crystal development. The first part of this review focuses on understanding the dramatic variations seen in snow crystal morphology as a function of temperature, a mystery that has remained largely unsolved since its discovery 75 years ago. To this end we examine the growth of simple hexagonal ice prisms in considerable detail, comparing crystal growth theory with laboratory measurements of growth rates under a broad range of conditions. This turns out to be a surprisingly rich problem, which ultimately originates from the unusual molecular structure of the ice surface and its sensitive dependence on temperature. With new clues from precision measurements of attachment kinetics, we are now just beginning to understand these structural changes at the ice surface and how they affect the crystal growth process. We also touch upon the mostly unexplored topic of how dilute chemical impurities can greatly alter the growth of snow crystals. The second part of this review examines pattern formation in snow crystals, with special emphasis on the growth of snow crystal dendrites. Again we treat this as a case study of the more general problem of dendritic growth during diffusion-limited solidification. Since snow crystals grow from the vapour, we can apply dendrite theory in the simplified slowgrowth limit where attachment kinetics dominates over capillarity in selecting the tip velocity. Although faceting is quite pronounced in these structures, many aspects of the formation of snow crystal dendrites are fairly well described using a theoretical treatment that does not explicitly incorporate faceting. We also describe electrically modified ice dendrite growth, which produces some novel needle-like structures.

/pdf/the-physics-of-snow-crystals-2vr2vatx5i.pdf

The physics of snow crystals

Kinetics of Homogeneous Nucleation in the Freezing of Large Water Clusters

Supercooling of water below the anomalous range near 226 k

Molecular dynamics simulations adopting the Born−Mayer−Huggins potential function were performed on a series of (NaCl)108 clusters to observe their properties during heating and cooling and to moni...

Molecular Dynamics Studies of the Kinetics of Freezing of (NaCl)108 Clusters

Molecular dynamics simulations have been carried out to study the effects of cluster size and temperature on the nucleation rate in potassium iodide clusters in the temperature range of 400−580 K. The clusters (KI)108, (KI)256, and (KI)500 were studied. The rate at which nuclei materialized per unit volume appeared to decrease with increasing cluster size. This size dependence could be accounted for by the agency of three roughly equal factors, namely, the Laplace pressure, the larger coefficients of diffusion for the smaller clusters, and the area-to-volume ratio. The latter factor arises because nucleation invariably occurs at the surface rather than in the interior of the clusters. Sizes of critical nuclei obtained by direct counting of ordered molecules were considerably larger than predicted by the classical nucleation theory unless the outer layer of ordered molecules was subtracted from the total count. The rationale for such a subtraction is that the outer layer corresponds to the ordered liquid l...

Jinfan Huang

Papers

Kinetics of Homogeneous Nucleation in the Freezing of Large Water Clusters

Supercooling of water below the anomalous range near 226 k

Molecular Dynamics Studies of the Kinetics of Freezing of (NaCl)108 Clusters

Molecular Dynamics Simulation of Nucleation in the Freezing of Molten Potassium Iodide Clusters

Structure and properties of potassium iodide nanoparticles. A molecular dynamics study