scholarly journals Ice is born in low-mobility regions of supercooled liquid water

2019 ◽  
Vol 116 (6) ◽  
pp. 2009-2014 ◽  
Author(s):  
Martin Fitzner ◽  
Gabriele C. Sosso ◽  
Stephen J. Cox ◽  
Angelos Michaelides
Keyword(s):  
Liquid Water ◽  
Dynamical Behavior ◽  
Supercooled Liquid ◽  
Ice Nucleation ◽  
Water Molecules ◽  
Ice Crystal ◽  
Surrounding Water ◽  
Dynamical Heterogeneity ◽  
Complex Dynamical Behavior

When an ice crystal is born from liquid water, two key changes occur: (i) The molecules order and (ii) the mobility of the molecules drops as they adopt their lattice positions. Most research on ice nucleation (and crystallization in general) has focused on understanding the former with less attention paid to the latter. However, supercooled water exhibits fascinating and complex dynamical behavior, most notably dynamical heterogeneity (DH), a phenomenon where spatially separated domains of relatively mobile and immobile particles coexist. Strikingly, the microscopic connection between the DH of water and the nucleation of ice has yet to be unraveled directly at the molecular level. Here we tackle this issue via computer simulations which reveal that (i) ice nucleation occurs in low-mobility regions of the liquid, (ii) there is a dynamical incubation period in which the mobility of the molecules drops before any ice-like ordering, and (iii) ice-like clusters cause arrested dynamics in surrounding water molecules. With this we establish a clear connection between dynamics and nucleation. We anticipate that our findings will pave the way for the examination of the role of dynamical heterogeneities in heterogeneous and solution-based nucleation.

scholarly journals Photomineralization mechanism changes the ability of dissolved organic matter to activate cloud droplets and to nucleate ice crystals

2019 ◽  
Vol 19 (19) ◽  
pp. 12397-12412 ◽  
Author(s):  
Nadine Borduas-Dedekind ◽  
Rachele Ossola ◽  
Robert O. David ◽  
Lin S. Boynton ◽  
Vera Weichlinger ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Dissolved Organic Matter ◽  
Organic Acids ◽  
Liquid Water ◽  
Supercooled Liquid ◽  
Ice Nucleation ◽  
Ice Crystals ◽  
Cloud Droplets ◽  
Photochemical Processing

Abstract. An organic aerosol particle has a lifetime of approximately 1 week in the atmosphere during which it will be exposed to sunlight. However, the effect of photochemistry on the propensity of organic matter to participate in the initial cloud-forming steps is difficult to predict. In this study, we quantify on a molecular scale the effect of photochemical exposure of naturally occurring dissolved organic matter (DOM) and of a fulvic acid standard on its cloud condensation nuclei (CCN) and ice nucleation (IN) activity. We find that photochemical processing, equivalent to 4.6 d in the atmosphere, of DOM increases its ability to form cloud droplets by up to a factor of 2.5 but decreases its ability to form ice crystals at a loss rate of −0.04 ∘CT50 h−1 of sunlight at ground level. In other words, the ice nucleation activity of photooxidized DOM can require up to 4 ∘C colder temperatures for 50 % of the droplets to activate as ice crystals under immersion freezing conditions. This temperature change could impact the ratio of ice to water droplets within a mixed-phase cloud by delaying the onset of glaciation and by increasing the supercooled liquid fraction of the cloud, thereby modifying the radiative properties and the lifetime of the cloud. Concurrently, a photomineralization mechanism was quantified by monitoring the loss of organic carbon and the simultaneous production of organic acids, such as formic, acetic, oxalic and pyruvic acids, CO and CO2. This mechanism explains and predicts the observed increase in CCN and decrease in IN efficiencies. Indeed, we show that photochemical processing can be a dominant atmospheric ageing process, impacting CCN and IN efficiencies and concentrations. Photomineralization can thus alter the aerosol–cloud radiative effects of organic matter by modifying the supercooled-liquid-water-to-ice-crystal ratio in mixed-phase clouds with implications for cloud lifetime, precipitation patterns and the hydrological cycle.Highlights. During atmospheric transport, dissolved organic matter (DOM) within aqueous aerosols undergoes photochemistry. We find that photochemical processing of DOM increases its ability to form cloud droplets but decreases its ability to form ice crystals over a simulated 4.6 d in the atmosphere. A photomineralization mechanism involving the loss of organic carbon and the production of organic acids, CO and CO2 explains the observed changes and affects the liquid-water-to-ice ratio in clouds.

scholarly journals The enhancement and suppression of immersion mode heterogeneous ice-nucleation by solutes

2018 ◽  
Vol 9 (17) ◽  
pp. 4142-4151 ◽  
Author(s):  
Thomas F. Whale ◽  
Mark A. Holden ◽  
Theodore W. Wilson ◽  
Daniel O'Sullivan ◽  
Benjamin J. Murray
Keyword(s):  
Liquid Water ◽  
Heterogeneous Nucleation ◽  
Alkali Halides ◽  
Supercooled Liquid ◽  
Ice Nucleation ◽  
Ammonium Salts ◽  
Atmospherically Relevant ◽  
Heterogeneous Ice Nucleation

Heterogeneous nucleation of ice from supercooled liquid water by some atmospherically relevant nucleators is enhanced by ammonium salts and suppressed by alkali halides.

scholarly journals Exploratory experiments on pre-activated freezing nucleation on mercuric iodide

2020 ◽  
Author(s):  
Gabor Vali
Keyword(s):  
Liquid Water ◽  
Laboratory Experiments ◽  
Ice Nucleation ◽  
Mercuric Iodide ◽  
Multiple Sample ◽  
Pore Condensation ◽  
Basic Level ◽  
Activation Cycle

Abstract. Pre-activation of freezing nucleation was examined in laboratory experiments with mercuric iodide suspensions in water. The experiments followed the procedure designed by Edwards, Evans and Zipper (1970) but employed multiple sample drops and many repetitions of the pre-activation cycle. The results obtained confirm the basic findings of the earlier work and refine it. By also drawing on the results of Seeley and Seidler (2001), pre-activated freezing nucleation (PFN in this work) is analyzed in search of constraints that help define the process responsible for it. No firm conclusions are reached, but evidence is accumulated pointing to the role of definite structures being involved in PFN, similar to the role of sites in heterogeneous freezing nucleation in general. PFN differs from pore condensation and freezing described by Marcolli (2020) and David et al. (2020) in that it takes place in liquid water. Further exploration of this process can help understading ice nucleation at the basic level and in its practical manifestations. The results call attention to an ice nucleation pathway hitherto barely explored and which can be expected to have consequences in how ice nucleation occurs in atmospheric clouds and in other systems.

scholarly journals Mechanism of ice nucleation in liquid water on alkali feldspars

2022 ◽  
Author(s):  
Alice Keinert ◽  
Kathrin Deck ◽  
Tilia Gädeke ◽  
Thomas Leisner ◽  
Alexei A. Kiselev
Keyword(s):  
Liquid Water ◽  
Heterogeneous Nucleation ◽  
Supercooled Liquid ◽  
Nucleation Site ◽  
Ice Nucleation ◽  
Natural Environments ◽  
Mineral Surfaces ◽  
Aqueous Interfaces ◽  
Alkali Feldspars

Crystallization of supercooled liquid water in most natural environments starts with heterogeneous nucleation of ice induced by a nucleation site. Mineral surfaces, which form the majority of aqueous interfaces in...

scholarly journals Observations of the Origin and Distribution of Ice in Cold, Warm, and Occluded Frontal Systems during the DIAMET Campaign

2014 ◽  
Vol 142 (11) ◽  
pp. 4230-4255 ◽  
Author(s):  
G. Lloyd ◽  
C. Dearden ◽  
T. W. Choularton ◽  
J. Crosier ◽  
K. N. Bower
Keyword(s):  
Case Studies ◽  
Cold Front ◽  
Supercooled Liquid ◽  
Ice Nucleation ◽  
Ice Crystal ◽  
Atmospheric Measurements ◽  
Radar Satellite ◽  
Cloud Tops ◽  
Ice Water ◽  
Water Contents

Abstract Three case studies in frontal clouds from the Diabatic Influences on Mesoscale Structures in Extratropical Storms (DIAMET) project are described to understand the microphysical development of the mixed phase regions of these clouds. The cases are a kata-type cold front, a wintertime warm front, and a summertime occluded frontal system. The clouds were observed by radar, satellite, and in situ microphysics measurements from the U.K. Facility for Airborne Atmospheric Measurements (FAAM) research aircraft. The kata cold front cloud was shallow with a cloud-top temperature of approximately −13°C. Cloud-top heterogeneous ice nucleation was found to be consistent with predictions by a primary ice nucleation scheme. The other case studies had high cloud tops (< −40°C) and despite no direct cloud-top measurements in these regions, homogeneous ice nucleation would be expected. The maximum ice crystal concentrations and ice water contents in all clouds were observed at temperatures around −5°C. Graupel was not observed, hence, secondary ice was produced by riming on snow falling through regions of supercooled liquid water. Within these regions substantial concentrations (10–150 L−1) of supercooled drizzle were observed. The freezing of these drops increases the riming rate due to the increase in rimer surface area. Increasing rime accretion has been shown to lead to higher ice splinter production rates. Despite differences in the cloud structure, the maximum ice crystal number concentration in all three clouds was ~100 L−1. Ice water contents were similar in the warm and occluded frontal cases, where median values in both cases reached ~0.2–0.3 g m−3, but lower in the cold front case.

Supercooled Liquid Water and Ice Crystal Distributions Within Sierra Nevada Winter Storms

1983 ◽  
Vol 22 (11) ◽  
pp. 1875-1886 ◽  
Author(s):  
Mark F. Heggli ◽  
Larry Vardiman ◽  
Ronald E. Stewart ◽  
Arlen Huggins
Keyword(s):  
Sierra Nevada ◽  
Liquid Water ◽  
Supercooled Liquid ◽  
Ice Crystal ◽  
Winter Storms

scholarly journals Role of Tf2N− anions in the ionic liquid–water distribution of europium(iii) chelates

RSC Advances ◽  
2017 ◽  
Vol 7 (13) ◽  
pp. 7610-7618 ◽  
Author(s):  
Hiroyuki Okamura ◽  
Noboru Aoyagi ◽  
Kojiro Shimojo ◽  
Hirochika Naganawa ◽  
Hisanori Imura
Keyword(s):  
Ionic Liquid ◽  
Fluorescence Spectroscopy ◽  
Liquid Water ◽  
Water Distribution ◽  
Laser Induced Fluorescence ◽  
Water Molecules ◽  
Time Resolved ◽  
Water Saturated

The replacement of water molecules of [Eu(tta)3(H2O)3] with Tf2N− was evidenced in water-saturated [Cnmim][Tf2N] by time-resolved laser-induced fluorescence spectroscopy.

Infrared study of the state of water in the hydration shell of DNA

1970 ◽  
Vol 48 (10) ◽  
pp. 1536-1542 ◽  
Author(s):  
Michael Falk ◽  
A. G. Poole ◽  
C. G. Goymour
Keyword(s):  
Liquid Water ◽  
Low Temperatures ◽  
Hydration Shell ◽  
The State ◽  
Water Molecules ◽  
Surrounding Water ◽  
Infrared Study ◽  
Hydration Shells ◽  
State Of Water ◽  
Bond Strengths

The state of water in the hydration shell of DNA was studied by infrared spectroscopy. The stretching bands of isotopically dilute HDO adsorbed on DNA have nearly the same band profiles as those of HDO in liquid water. This indicates a distribution of hydrogen-bond strengths similar to that in liquid water. At low temperatures, the spectra show that an inner layer of about 10 water molecules per nucleotide is incapable of crystallization, even when the surrounding water crystallizes into ice I. The biopolymer hydration shells are not "ice-like" in the sense of crystalline ordering into an ice-like structure.

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