Experimental quantification of contact freezing in an electrodynamic balance

Hoffmann, Nadine; Kiselev, Alexei; Rzesanke, Daniel; Duft, Denis; Leisner, Thomas

doi:10.5194/amt-6-2373-2013

Cited by 35 publications

(52 citation statements)

References 40 publications

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“…In accordance with our experiments, they found a clear shift to lower freezing temperatures when changing from contact to immersion mode experiments. 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.…”

Section: Kaolinitementioning

confidence: 99%

“…While the uncertainty associated with the measurements at 2 s is quite large, this data still seems significantly lower than the 4 s residence time freezing efficiencies. An increasing freezing efficiency with increasing residence time is expected for immersion freezing (Hoffmann et al, 2013b;Welti et al, 2012) and adhesion freezing. Therefore, it is likely that freezing occurs due to one of these mechanisms rather than collisional contact freezing.…”

Section: Freezing Efficiency Of Silver Iodide Particlesmentioning

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: Kaolinitementioning

confidence: 99%

Section: Freezing Efficiency Of Silver Iodide Particlesmentioning

confidence: 99%

Comparing contact and immersion freezing from continuous flow diffusion chambers

et al. 2016

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“…[27][28][29] The unique feature of the present experimental setup is that the EDB is coupled to a Raman microscope and is connected to a humidity control system (Fig. 1).…”

Section: A the Edb Setupmentioning

confidence: 99%

“…The accommodation of the each droplet to the temperature inside the EDB is completed within about 1 s. 30 The size of a suspended droplet is measured continuously by analyzing the two-dimensional angle-resolved scattering pattern recorded with a CCD camera installed at a right angle to the beam of the HeNe laser 28,29 (see supplementary material for details). Shadow images of the droplets and residual particles have been recorded with the Raman microscope, providing additional information about the morphology, the phase, and the size of the particles.…”

Section: A the Edb Setupmentioning

confidence: 99%

Temperature-dependent formation of NaCl dihydrate in levitated NaCl and sea salt aerosol particles

Peckhaus¹,

Kiselev²,

Wagner³

et al. 2016

The Journal of Chemical Physics

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Recent laboratory studies indicate that the hydrated form of crystalline NaCl is potentially important for atmospheric processes involving depositional ice nucleation on NaCl dihydrate particles under cirrus cloud conditions. However, recent experimental studies reported a strong discrepancy between the temperature intervals where the efflorescence of NaCl dihydrate has been observed. Here we report the measurements of the volume specific nucleation rate of crystalline NaCl in the aqueous solution droplets of pure NaCl suspended in an electrodynamic balance at constant temperature and humidity in the range from 250 K to 241 K. Based on these measurements, we derive the interfacial energy of crystalline NaCl dihydrate in a supersaturated NaCl solution and determined its temperature dependence. Taking into account both temperature and concentration dependence of nucleation rate coefficients, we explain the difference in the observed fractions of NaCl dihydrate reported in the previous studies. Applying the heterogeneous classical nucleation theory model, we have been able to reproduce the 5 K shift of the NaCl dihydrate efflorescence curve observed for the sea salt aerosol particles, assuming the presence of super-micron solid inclusions (hypothetically gypsum or hemihydrate of CaSO 4 ). These results support the notion that the phase transitions in microscopic droplets of supersaturated solution should be interpreted by accounting for the stochastic nature of homogeneous and heterogeneous nucleation and cannot be understood on the ground of bulk phase diagrams alone.

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“…The freezing temperature of INPs either immersed in or in contact with levitated supercooled water droplets suspended in the air can also be determined by the change in light scattering with a charge-coupled device (CCD) camera using an electrodynamic balance (EDB; Hoffmann et al, 2013), an acoustic levitator (Diehl et al, 2014) or in a vertical wind tunnel (Szakáll et al, 2009). The advantage of these methods is the ability to provide, via high-resolution images, substratefree information for statistically representative ice nucleation processes on a single droplet basis.…”

Section: State Of the Art Of In Measurement Techniquesmentioning

confidence: 99%

A comprehensive laboratory study on the immersion freezing behavior of illite NX particles: a comparison of 17 ice nucleation measurement techniques

et al. 2015

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Abstract. Immersion freezing is the most relevant heterogeneous ice nucleation mechanism through which ice crystals are formed in mixed-phase clouds. In recent years, an increasing number of laboratory experiments utilizing a variety of instruments have examined immersion freezing activity of atmospherically relevant ice-nucleating particles. However, an intercomparison of these laboratory results is a difficult task because investigators have used different ice nucleation (IN) measurement methods to produce these results. A remaining challenge is to explore the sensitivity and accuracy of these techniques and to understand how the IN results are potentially influenced or biased by experimental parameters associated with these techniques.Within the framework of INUIT (Ice Nuclei Research Unit), we distributed an illite-rich sample (illite NX) as a representative surrogate for atmospheric mineral dust particles to investigators to perform immersion freezing experiments using different IN measurement methods and to obtain Published by Copernicus Publications on behalf of the European Geosciences Union. N. Hiranuma et al.: A comparison of 17 IN measurement techniquesIN data as a function of particle concentration, temperature (T ), cooling rate and nucleation time. A total of 17 measurement methods were involved in the data intercomparison. Experiments with seven instruments started with the test sample pre-suspended in water before cooling, while 10 other instruments employed water vapor condensation onto drydispersed particles followed by immersion freezing. The resulting comprehensive immersion freezing data set was evaluated using the ice nucleation active surface-site density, n s , to develop a representative n s (T ) spectrum that spans a wide temperature range (−37 • C < T < −11 • C) and covers 9 orders of magnitude in n s .In general, the 17 immersion freezing measurement techniques deviate, within a range of about 8 • C in terms of temperature, by 3 orders of magnitude with respect to n s . In addition, we show evidence that the immersion freezing efficiency expressed in n s of illite NX particles is relatively independent of droplet size, particle mass in suspension, particle size and cooling rate during freezing. A strong temperature dependence and weak time and size dependence of the immersion freezing efficiency of illite-rich clay mineral particles enabled the n s parameterization solely as a function of temperature. We also characterized the n s (T ) spectra and identified a section with a steep slope between −20 and −27 • C, where a large fraction of active sites of our test dust may trigger immersion freezing. This slope was followed by a region with a gentler slope at temperatures below −27 • C. While the agreement between different instruments was reasonable below ∼ −27 • C, there seemed to be a different trend in the temperature-dependent ice nucleation activity from the suspension and dry-dispersed particle measurements for this mineral dust, in particular at higher temperatures. For instance,...

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Experimental quantification of contact freezing in an electrodynamic balance

Cited by 35 publications

References 40 publications

Comparing contact and immersion freezing from continuous flow diffusion chambers

Comparing contact and immersion freezing from continuous flow diffusion chambers

Temperature-dependent formation of NaCl dihydrate in levitated NaCl and sea salt aerosol particles

A comprehensive laboratory study on the immersion freezing behavior of illite NX particles: a comparison of 17 ice nucleation measurement techniques

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