Pre-activation of ice-nucleating particles by the pore condensation and  freezing mechanism

Wagner, Robert; Kiselev, Alexei; Möhler, Ottmar; Saathoff, H.; Steinke, Isabelle

doi:10.5194/acp-16-2025-2016

Cited by 48 publications

(86 citation statements)

References 43 publications

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“…Illite NX, diatomaceous earth, two types of zeolites (CBV100 and CBV400), GSG (Graphite Spark Generator) soot, and a natural dust from the Canary Islands (CID) were susceptible to pre-activation, while dust samples from the Sahara (SD2) and Israel (ID), volcanic ash from the Eyjafjallajökull eruption on Iceland in April 2010 (EY01), and water-processed GSG soot did not respond to pre-activation. In all cases, pre-activation was lost when the particles were heated to T > 260 K. For pre-activation by cooling to 228 K at RH i = 95 % and ice crystal growth up to 259 K at RH i > 100 %, pore openings with diameters < 6.5 nm are needed to keep pores filled and pore cavities with diameters > 9 nm are needed to preserve ice up to 259 K. These numbers are in agreement with the conclusions by Wagner et al (2016) that pores with diameters between about 5 and 8 nm contribute to pre-activation under ice-subsaturated conditions. Wagner et al (2016) also compared the susceptibility to pre-activation with the intrinsic ability of particles to nucleate an ice cloud, revealing that samples, which responded to pre-activation, produced dense ice clouds during expansion runs performed at temperatures below the homogeneous ice nucleation threshold, when relative humidity exceeded ice saturation.…”

Section: Aida Chamber Experiments By Wagner Et Al (2016)supporting

confidence: 80%

“…In all cases, pre-activation was lost when the particles were heated to T > 260 K. For pre-activation by cooling to 228 K at RH i = 95 % and ice crystal growth up to 259 K at RH i > 100 %, pore openings with diameters < 6.5 nm are needed to keep pores filled and pore cavities with diameters > 9 nm are needed to preserve ice up to 259 K. These numbers are in agreement with the conclusions by Wagner et al (2016) that pores with diameters between about 5 and 8 nm contribute to pre-activation under ice-subsaturated conditions. Wagner et al (2016) also compared the susceptibility to pre-activation with the intrinsic ability of particles to nucleate an ice cloud, revealing that samples, which responded to pre-activation, produced dense ice clouds during expansion runs performed at temperatures below the homogeneous ice nucleation threshold, when relative humidity exceeded ice saturation. Illite NX exhibited a nucleated fraction of 0.58 at T ∼ = 229 K and RH i < 105 % due to homogeneous freezing of pore water, indicating the presence of pores with diameters between about 3 and 8.5 nm.…”

Section: Aida Chamber Experiments By Wagner Et Al (2016)supporting

confidence: 80%

“…The pre-activation procedure used by Wagner et al (2016) is only effective for narrow pores. Pre-activation of wider pores needs higher relative humidity and/or warmer temperatures so that water can condense in them.…”

Section: Aida Chamber Experiments By Wagner Et Al (2016)mentioning

confidence: 99%

“…Therefore, ice cannot form in them. Wagner et al (2016). T preact -pre-activation temperature; RH preact -pre-activation RH with respect to ice; RH start -RH with respect to ice at the start of the expansion run; T start -starting temperature of the expansion run; T crycrystallization temperature; RH cry -crystallization RH with respect to ice; F cry -crystallized particle fraction; D pore -pore diameter needed to prevent ice from melting; S w -water saturation.…”

Section: Aida Chamber Experiments By Wagner Et Al (2016)mentioning

confidence: 99%

“…Research on pre-activation ceased in the early 1970s and was only resumed 3 decennials later by Knopf and Koop (2006), who clearly favoured the survival of ice in pores and capillaries as the explanation for pre-activation. More recently, Wagner et al (2016) analysed the pre-activation behaviour of different particles, presuming that pre-activation is due to capillary condensation of supercooled water and subsequent homogeneous freezing.…”

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confidence: 99%

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Pre-activation of aerosol particles by ice preserved in pores

Marcolli

2017

Atmos. Chem. Phys.

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Abstract. Pre-activation denotes the capability of particles or materials to nucleate ice at lower relative humidities or higher temperatures compared to their intrinsic ice nucleation efficiency after having experienced an ice nucleation event or low temperature before. This review presumes that ice preserved in pores is responsible for pre-activation and analyses pre-activation under this presumption. Idealized trajectories of air parcels are used to discuss the pore characteristics needed for ice to persist in pores and to induce macroscopic ice growth out of the pores. The pore width needed to keep pores filled with water decreases with decreasing relative humidity as described by the inverse Kelvin equation. Thus, narrow pores remain filled with ice well below ice saturation. However, the smaller the pore width, the larger the melting and freezing point depressions within the pores. Therefore, pre-activation due to pore ice is constrained by the melting of ice in narrow pores and the sublimation of ice from wide pores imposing restrictions on the temperature and relative humidity range of pre-activation for cylindrical pores. Ice is better protected in ink-bottle-shaped pores with a narrow opening leading to a large cavity. However, whether pre-activation is efficient also depends on the capability of ice to grow macroscopically, i.e. out of the pore. A strong effect of pre-activation is expected for swelling pores, because at low relative humidity (RH) their openings narrow and protect the ice within them against sublimation. At high relative humidities, they open up and the ice can grow to macroscopic size and form an ice crystal. Similarly, ice protected in pockets is perfectly sheltered against sublimation but needs the dissolution of the surrounding matrix to be effective. Pores partially filled with condensable material may also show preactivation. In this case, complete filling occurs at lower RH than for empty pores and freezing shifts to lower temperatures.Pre-activation experiments confirm that materials susceptible to pre-activation are indeed porous. Pre-activation was observed for clay minerals like illite, kaolinite, and montmorillonite with inherent porosity. The largest effect was observed for the swelling clay mineral montmorillonite. Some materials may acquire porosity, depending on the formation and processing conditions. Particles of CaCO 3 , meteoritic material, and volcanic ash showed pre-activation for some samples or in some studies but not in other ones. Quartz and silver iodide were not susceptible to pre-activation.Atmospheric relevance of pre-activation by ice preserved in pores may not be generally given but depend on the atmospheric scenario. Lower-level cloud seeding by pre-activated particles released from high-level clouds crucially depends on the ability of pores to retain ice at the relative humidities and temperatures of the air masses they pass through. Porous particles that are recycled in wave clouds may show pre-activation with subsequent ice growth as soon as ice sat...

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Section: Aida Chamber Experiments By Wagner Et Al (2016)supporting

confidence: 80%

Section: Aida Chamber Experiments By Wagner Et Al (2016)supporting

confidence: 80%

Section: Aida Chamber Experiments By Wagner Et Al (2016)mentioning

confidence: 99%

Section: Aida Chamber Experiments By Wagner Et Al (2016)mentioning

confidence: 99%

mentioning

confidence: 99%

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Pre-activation of aerosol particles by ice preserved in pores

Marcolli

2017

Atmos. Chem. Phys.

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Electrodynamics of Aqueous Media

Артемов

2021

Springer Series in Chemical Physics

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Silica as a Model Ice-Nucleating Particle to Study the Effects of Crystallinity, Porosity, and Low-Density Surface Functional Groups on Immersion Freezing

et al. 2022

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Aerosol particles can facilitate heterogeneous ice formation in the troposphere and stratosphere by acting as ice-nucleating particles, modulating cloud formation/dissipation, precipitation, and their microphysical properties. Heterogeneous ice nucleation is driven by ice embryo formation on the particle surface, which can be influenced by features of the surface such as crystallinity, surface structure, lattice structure, defects, and functional groups. To characterize the effect of crystallinity, pores, and surface functional groups toward ice nucleation, samples of comparable silica systems, specifically, quartz, ordered and nonordered porous amorphous silica samples with a range of pore sizes (2–11 nm), and nonporous functionalized silica spheres, were used as models for mineral dust aerosol particles. The ice nucleation activity of these samples was investigated by using an immersion freezing chamber. The results suggest that crystallinity has a larger effect than porosity on ice nucleation activity, as all of the porous silica samples investigated had lower onset freezing temperatures and lower ice nucleation activities than quartz. Our findings also suggest that pores alone are not sufficient to serve as effective active sites and need some additional chemical or physical property, like crystallinity, to nucleate ice in immersion mode freezing. The addition of a low density of organic functional groups to nonporous samples showed little enhancement compared to the inherent nucleation activity of silica with native surface hydroxyl groups. The density of functional groups investigated in this work suggests that a different arrangement of surface groups may be needed for enhanced immersion mode ice nucleation activity. In summary, crystallinity dictates the ice nucleation activity of silica samples rather than porosity or low-density surface functional groups. This work has broader implications regarding the climate impacts resulting from ice cloud formation.

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Pre-activation of ice-nucleating particles by the pore condensation and freezing mechanism

Cited by 48 publications

References 43 publications

Pre-activation of aerosol particles by ice preserved in pores

Pre-activation of aerosol particles by ice preserved in pores

Electrodynamics of Aqueous Media

Silica as a Model Ice-Nucleating Particle to Study the Effects of Crystallinity, Porosity, and Low-Density Surface Functional Groups on Immersion Freezing

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