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Pore condensation and freezing is responsible for ice formation below water saturation for porous particles

Ice nucleation in the atmosphere influences cloud properties, altering precipitation and the radiative balance, ultimately regulating Earth’s climate. An accepted ice nucleation pathway, known as deposition nucleation, assumes a direct transition of water from the vapor to the ice phase, without an...

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Autores principales: David, Robert O., Marcolli, Claudia, Fahrni, Jonas, Qiu, Yuqing, Perez Sirkin, Yamila A., Molinero, Valeria, Mahrt, Fabian, Brühwiler, Dominik, Lohmann, Ulrike, Kanji, Zamin A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6486705/
https://www.ncbi.nlm.nih.gov/pubmed/30948638
http://dx.doi.org/10.1073/pnas.1813647116
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author David, Robert O.
Marcolli, Claudia
Fahrni, Jonas
Qiu, Yuqing
Perez Sirkin, Yamila A.
Molinero, Valeria
Mahrt, Fabian
Brühwiler, Dominik
Lohmann, Ulrike
Kanji, Zamin A.
author_facet David, Robert O.
Marcolli, Claudia
Fahrni, Jonas
Qiu, Yuqing
Perez Sirkin, Yamila A.
Molinero, Valeria
Mahrt, Fabian
Brühwiler, Dominik
Lohmann, Ulrike
Kanji, Zamin A.
author_sort David, Robert O.
collection PubMed
description Ice nucleation in the atmosphere influences cloud properties, altering precipitation and the radiative balance, ultimately regulating Earth’s climate. An accepted ice nucleation pathway, known as deposition nucleation, assumes a direct transition of water from the vapor to the ice phase, without an intermediate liquid phase. However, studies have shown that nucleation occurs through a liquid phase in porous particles with narrow cracks or surface imperfections where the condensation of liquid below water saturation can occur, questioning the validity of deposition nucleation. We show that deposition nucleation cannot explain the strongly enhanced ice nucleation efficiency of porous compared with nonporous particles at temperatures below −40 °C and the absence of ice nucleation below water saturation at −35 °C. Using classical nucleation theory (CNT) and molecular dynamics simulations (MDS), we show that a network of closely spaced pores is necessary to overcome the barrier for macroscopic ice-crystal growth from narrow cylindrical pores. In the absence of pores, CNT predicts that the nucleation barrier is insurmountable, consistent with the absence of ice formation in MDS. Our results confirm that pore condensation and freezing (PCF), i.e., a mechanism of ice formation that proceeds via liquid water condensation in pores, is a dominant pathway for atmospheric ice nucleation below water saturation. We conclude that the ice nucleation activity of particles in the cirrus regime is determined by the porosity and wettability of pores. PCF represents a mechanism by which porous particles like dust could impact cloud radiative forcing and, thus, the climate via ice cloud formation.
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spelling pubmed-64867052019-05-07 Pore condensation and freezing is responsible for ice formation below water saturation for porous particles David, Robert O. Marcolli, Claudia Fahrni, Jonas Qiu, Yuqing Perez Sirkin, Yamila A. Molinero, Valeria Mahrt, Fabian Brühwiler, Dominik Lohmann, Ulrike Kanji, Zamin A. Proc Natl Acad Sci U S A Physical Sciences Ice nucleation in the atmosphere influences cloud properties, altering precipitation and the radiative balance, ultimately regulating Earth’s climate. An accepted ice nucleation pathway, known as deposition nucleation, assumes a direct transition of water from the vapor to the ice phase, without an intermediate liquid phase. However, studies have shown that nucleation occurs through a liquid phase in porous particles with narrow cracks or surface imperfections where the condensation of liquid below water saturation can occur, questioning the validity of deposition nucleation. We show that deposition nucleation cannot explain the strongly enhanced ice nucleation efficiency of porous compared with nonporous particles at temperatures below −40 °C and the absence of ice nucleation below water saturation at −35 °C. Using classical nucleation theory (CNT) and molecular dynamics simulations (MDS), we show that a network of closely spaced pores is necessary to overcome the barrier for macroscopic ice-crystal growth from narrow cylindrical pores. In the absence of pores, CNT predicts that the nucleation barrier is insurmountable, consistent with the absence of ice formation in MDS. Our results confirm that pore condensation and freezing (PCF), i.e., a mechanism of ice formation that proceeds via liquid water condensation in pores, is a dominant pathway for atmospheric ice nucleation below water saturation. We conclude that the ice nucleation activity of particles in the cirrus regime is determined by the porosity and wettability of pores. PCF represents a mechanism by which porous particles like dust could impact cloud radiative forcing and, thus, the climate via ice cloud formation. National Academy of Sciences 2019-04-23 2019-04-04 /pmc/articles/PMC6486705/ /pubmed/30948638 http://dx.doi.org/10.1073/pnas.1813647116 Text en Copyright © 2019 the Author(s). Published by PNAS. https://creativecommons.org/licenses/by-nc-nd/4.0/ This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND) (https://creativecommons.org/licenses/by-nc-nd/4.0/) .
spellingShingle Physical Sciences
David, Robert O.
Marcolli, Claudia
Fahrni, Jonas
Qiu, Yuqing
Perez Sirkin, Yamila A.
Molinero, Valeria
Mahrt, Fabian
Brühwiler, Dominik
Lohmann, Ulrike
Kanji, Zamin A.
Pore condensation and freezing is responsible for ice formation below water saturation for porous particles
title Pore condensation and freezing is responsible for ice formation below water saturation for porous particles
title_full Pore condensation and freezing is responsible for ice formation below water saturation for porous particles
title_fullStr Pore condensation and freezing is responsible for ice formation below water saturation for porous particles
title_full_unstemmed Pore condensation and freezing is responsible for ice formation below water saturation for porous particles
title_short Pore condensation and freezing is responsible for ice formation below water saturation for porous particles
title_sort pore condensation and freezing is responsible for ice formation below water saturation for porous particles
topic Physical Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6486705/
https://www.ncbi.nlm.nih.gov/pubmed/30948638
http://dx.doi.org/10.1073/pnas.1813647116
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