Freezing of water droplets colliding with kaolinite particles

Svensson, Erik; Delval, Christophe; Hessberg, P. von; Johnson, Matthew S.; Pettersson, Jan B. C.

doi:10.5194/acp-9-4295-2009

Cited by 35 publications

(55 citation statements)

References 33 publications

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“…The wetting state of a nucleus may therefore be a crucial parameter for ice nucleation by kaolinite. This would be in accordance with the higher nucleation temperatures observed by Svensson et al (2009) in humid conditions and point to an adhesion freezing mechanism.…”

Section: Kaolinitesupporting

confidence: 77%

“…Hoffmann et al (2013b) found that contact freezing dominates over immersion freezing for droplets levitated in an electrodynamic balance that were exposed to a flow of particles of kaolinite KGa-1b. Svensson et al (2009) investigated contact freezing using an electrodynamic balance to levitate droplets exposed to a flow of Fluka kaolinite particles. They observed contact freezing below 249 K for dry conditions and a freezing threshold of 267 K when the air was humidified.…”

Section: Kaolinitementioning

confidence: 99%

“…Kaolinite is a clay mineral and accounts for 13 % of dust mass in the atmosphere (Atkinson et al, 2013). It has been studied previously in immersion freezing (e.g., Welti et al, 2012) and contact freezing studies (e.g., Ladino et al, 2011;Svensson et al, 2009). ATD has been previously studied for immersion freezing by Marcolli et al (2007) and Niedermeier et al (2010) and for contact freezing by Niehaus et al (2014).…”

Section: Introductionmentioning

confidence: 99%

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Comparing contact and immersion freezing from continuous flow diffusion chambers

et al. 2016

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Abstract. Ice nucleating particles (INPs) in the atmosphere are responsible for glaciating cloud droplets between 237 and 273 K. Different mechanisms of heterogeneous ice nucleation can compete under mixed-phase cloud conditions. Contact freezing is considered relevant because higher ice nucleation temperatures than for immersion freezing for the same INPs were observed. It has limitations because its efficiency depends on the number of collisions between cloud droplets and INPs. To date, direct comparisons of contact and immersion freezing with the same INP, for similar residence times and concentrations, are lacking. This study compares immersion and contact freezing efficiencies of three different INPs. The contact freezing data were obtained with the ETH CoLlision Ice Nucleation CHamber (CLINCH) using 80 µm diameter droplets, which can interact with INPs for residence times of 2 and 4 s in the chamber. The contact freezing efficiency was calculated by estimating the number of collisions between droplets and particles. Theoretical formulations of collision efficiencies gave too high freezing efficiencies for all investigated INPs, namely AgI particles with 200 nm electrical mobility diameter, 400 and 800 nm diameter Arizona Test Dust (ATD) and kaolinite particles. Comparison of freezing efficiencies by contact and immersion freezing is therefore limited by the accuracy of collision efficiencies. The concentration of particles was 1000 cm −3 for ATD and kaolinite and 500, 1000, 2000 and 5000 cm −3 for AgI. For concentrations < 5000 cm −3 , the droplets collect only one particle on average during their time in the chamber. For ATD and kaolinite particles, contact freezing efficiencies at 2 s residence time were smaller than at 4 s, which is in disagreement with a collisional contact freezing process but in accordance with immersion freezing or adhesion freezing. With "adhesion freezing", we refer to a contact nucleation process that is enhanced compared to immersion freezing due to the position of the INP on the droplet, and we discriminate it from collisional contact freezing, which assumes an enhancement due to the collision of the particle with the droplet. For best comparison with contact freezing results, immersion freezing experiments of the same INPs were performed with the continuous flow diffusion chamber Immersion Mode Cooling chAmber-Zurich Ice Nucleation Chamber (IMCA-ZINC) for a 3 s residence time. In IMCA-ZINC, each INP is activated into a droplet in IMCA and provides its surface for ice nucleation in the ZINC chamber. The comparison of contact and immersion freezing results did not confirm a general enhancement of freezing efficiency for contact compared with immersion freezing experiments. For AgI particles the onset of heterogeneous freezing in CLINCH was even shifted to lower temperatures compared with IMCA-ZINC. For ATD, freezing efficiencies for contact and immersion freezing experiments were similar. For kaolinite particles, contact freezing became detectable at higher temperatures than imm...

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Section: Kaolinitesupporting

confidence: 77%

Section: Kaolinitementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparing contact and immersion freezing from continuous flow diffusion chambers

et al. 2016

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“…Lee and Chan, 2007;Pope et al, 2010c;Lee et al, 2012), and supercooled droplets and ice nucleation (e.g. Swanson et al, 1999;Svensson et al, 2009;Hoffmann et al, 2013a, b;Stöckel et al, 2005). Recently, a new EDB design with concentric cylindrical electrodes was developed to measure the rapid evaporation and condensation process of single droplets (Heinisch et al, 2006(Heinisch et al, , 2009Davies et al, 2012Davies et al, , 2013.…”

Section: H-j Tong Et Al: a New Electrodynamic Balance (Edb) Designmentioning

confidence: 99%

A new electrodynamic balance (EDB) design for low-temperature studies: application to immersion freezing of pollen extract bioaerosols

et al. 2015

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Abstract. In this paper we describe a newly designed cold electrodynamic balance (CEDB) system, built to study the evaporation kinetics and freezing properties of supercooled water droplets. The temperature of the CEDB chamber at the location of the levitated water droplet can be controlled in the range −40 to +40 • C, which is achieved using a combination of liquid nitrogen cooling and heating by positive temperature coefficient heaters. The measurement of liquid droplet radius is obtained by analysing the Mie elastic light scattering from a 532 nm laser. The Mie scattering signal was also used to characterise and distinguish droplet freezing events; liquid droplets produce a regular fringe pattern, whilst the pattern from frozen particles is irregular. The evaporation rate of singly levitated water droplets was calculated from time-resolved measurements of the radii of evaporating droplets and a clear trend of the evaporation rate on temperature was measured. The statistical freezing probabilities of aqueous pollen extracts (pollen washing water) are obtained in the temperature range −4.5 to −40 • C. It was found that that pollen washing water from water birch (Betula fontinalis occidentalis) pollen can act as ice nuclei in the immersion freezing mode at temperatures as warm as −22.45 (±0.65) • C. Furthermore it was found that the protein-rich component of the washing water was significantly more iceactive than the non-proteinaceous component.

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“…There have been relatively few laboratory studies on contact freezing when compared with other ice nucleation modes (Pitter and Pruppacher 1973;Levin and Yankofsky 1983;Diehl and Mitra 1998;Diehl et al 2002;Durant and Shaw 2005;Shaw et al 2005;Svensson et al 2009;Fornea et al 2009;Ladino et al 2011). These past studies have shown that most IN (such as mineral dust, bacteria, pollen and volcanic ash) nucleate ice at warmer temperatures than immersion freezing and deposition in the contact mode by up to 10°C, thus suggesting that contact freezing should dominate other heterogeneous ice nucleation modes.…”

Section: Discussionmentioning

confidence: 99%

Relative importance of acid coating on ice nuclei in the deposition and contact modes for wintertime Arctic clouds and radiation

Girard

Asl

2013

Meteorol Atmos Phys

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Aerosols emitted from volcanic activities and polluted mid-latitudes regions are efficiently transported over the Arctic during winter by the large-scale atmospheric circulation. These aerosols are highly acidic. The acid coating on ice nuclei, which are present among these aerosols, alters their ability to nucleate ice crystals. In this research, the effect of acid coating on deposition and contact ice nuclei on the Arctic cloud and radiation is evaluated for January 2007 using a regional climate model. Results show that the suppression of contact freezing by acid coating on ice nuclei leads to small changes of the cloud microstructure and has no significant effect on the cloud radiative forcing (CRF) at the top of the atmosphere when compared with the effect of the alteration of deposition ice nucleation by acid coating on deposition ice nuclei. There is a negative feedback by which the suppression of contact freezing leads to an increase of the ice crystal nucleation rate by deposition ice nucleation. As a result, the suppression of contact freezing leads to an increase of the cloud ice crystal concentration. Changes in the cloud liquid and ice water contents remain small and the CRF is not significantly modified. The alteration of deposition ice nucleation by acid coating on ice nuclei is dominant over the alteration of contact freezing.

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Freezing of water droplets colliding with kaolinite particles

Cited by 35 publications

References 33 publications

Comparing contact and immersion freezing from continuous flow diffusion chambers

Comparing contact and immersion freezing from continuous flow diffusion chambers

A new electrodynamic balance (EDB) design for low-temperature studies: application to immersion freezing of pollen extract bioaerosols

Relative importance of acid coating on ice nuclei in the deposition and contact modes for wintertime Arctic clouds and radiation

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