Homogeneous Condensation—Freezing Nucleation Rate Measurements for Small Water Droplets in an Expansion Cloud Chamber

Hagen, Donald E.; Anderson, Rodney J.; Kassner, James L.

doi:10.1175/1520-0469(1981)038<1236:hcnrmf>2.0.co;2

Cited by 84 publications

(112 citation statements)

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“…We first look at g a , the activation energy for the transfer of a water molecule across the waterice boundary. Hagen et al (1981) applied an approach similar to ours to analyze measurement data of nucleation rate, but for homogeneous freezing, to derive g a . They obtained 8×10 −20 J (per H 2 O molecule) for g a at −40 • C, and this value roughly increases by 0.3×10 −20 per degree K of temperature rise.…”

Section: Verification Of Resultsmentioning

confidence: 99%

“…If their calculation can be extrapolated to the −29 • C. Note that the activation energy g a might have different controlling mechanisms at different temperatures. Hagen et al (1981) suggested that at temperatures warmer than −29 • C, the transfer of water molecules across the water-ice interface is limited by the self-diffusion through the bulk water, while at temperatures lower than −32 • C the transfer is by large water clusters.…”

Section: Verification Of Resultsmentioning

confidence: 99%

“…The rate of heterogeneous nucleation per particle is proportional to particle's total surface area and the rate of surface nucleation J s ; whereas J s is determined by the number of critical embryo per unit area n * , and the rate at which the critical embryo may gain one molecule through interaction with the parent phase A 1 to overcome the nucleation energy barrier (Mason, 1971, p. 474-478;Hagen et al, 1981;Pruppacher and Klett, 1997, p. 303):…”

Section: Classical Nucleation Theorymentioning

confidence: 99%

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Parameterizing ice nucleation rates using contact angle and activation energy derived from laboratory data

2008

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Abstract. The rate of ice nucleation in clouds is not easily determined and large discrepancies exist between model predictions and actual ice crystal concentration measured in clouds. In an effort to improve the parameterization of ice nucleating in cloud models, we investigate the rate of heterogeneous ice nucleation under specific ambient conditions by knowing the sizes as well as two thermodynamic parameters of the ice nuclei -contact angle and activation energy. Laboratory data of freezing and deposition nucleation modes were analyzed to derive inversely the two thermodynamic parameters for a variety of ice nuclei, including mineral dusts, bacteria, pollens, and soot particles. The analysis considered the Zeldovich factor for the adjustment of ice germ formation, as well as the solute and curvature effects on surface tension; the latter effects have strong influence on the contact angle. Contact angle turns out to be a more important factor than the activation energy in discriminating the nucleation capabilities of various ice nuclei species. By extracting these thermodynamic parameters, laboratory results can be converted into a formulation that follows classical nucleation theory, which then has the flexibility of incorporating factors such as the solute effect and curvature effect that were not considered in the experiments.

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Section: Verification Of Resultsmentioning

confidence: 99%

Section: Verification Of Resultsmentioning

confidence: 99%

Section: Classical Nucleation Theorymentioning

confidence: 99%

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Parameterizing ice nucleation rates using contact angle and activation energy derived from laboratory data

2008

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“…The surface nucleation rate obtained by Kuhn et al [32] at T = 236 K is about 10 , a value about equal to the one obtained by converting the data of DeMott and Rogers [21], at the same temperature, from volume to surface nucleation. The same assessment can be made for the Hagen et al [37] data, who obtained an even higher nucleation rate than DeMott and Rogers [21] in a similar experiment performed with lower radius droplets (r ~ 0.1 μm).…”

Section: Reported Datamentioning

confidence: 75%

Does the Homogeneous Ice Nucleation Initiate in the Bulk Volume or at the Surface of Super-Cooled Water Droplets? A Review

Santachiara¹,

Belosi²

2014

ACS

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The formation of ice in clouds can occur through primary processes, either homogeneously or heterogeneously triggered by aerosol particles called ice nuclei, as well as through secondary processes. The homogeneous ice nucleation process involves only pure water or solution droplets. Homogeneous freezing is crucial for the microphysics in the formation of high-altitude cirrus and polar stratospheric clouds, and also in the glaciation of thunderclouds, at temperatures below about 235 K. Nucleation rates in supercooled water have been measured using different experimental techniques: expansion cloud chambers, water-in-oil emulsions, levitation methods, free falling droplets, supersonic nozzles, field measurements, and molecular dynamics simulations. An important question concerns the possibility that the nucleation process in supercooled water can occur not only in the interior volume of the droplet, but even at or close to its surface. Even if there is no conclusive evidence, the majority of experimental and theoretical results suggest that the contribution of surface nucleation increases with decreasing radius of the supercooled droplets, and the surface (or sub-surface) nucleation rate is prevalent for droplets with radius lower than about 5 μm. If homogeneous freezing initiates at the droplet surface, the freezing rate should depend on the droplet size, and even a slight contamination by molecules within the surface layer could hamper the rate of the nucleation process.

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“…(16) and (11), using G act,07 and Eq. (14) Koop et al, 2000Bartell and Chushak, 2003Manka et al, 2012Hagen et al, 1981Pruppacher, 1995Riechers et al, 2013Taborek et al, 1985Larson and Swanson, 2006 a w =1 Figure 4. Homogeneous ice nucleation rate calculated using Eq.…”

Section: Discussionmentioning

confidence: 99%

Thermodynamic derivation of the activation energy for ice nucleation

Barahona

2015

Atmos. Chem. Phys.

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Abstract. Cirrus clouds play a key role in the radiative and hydrological balance of the upper troposphere. Their correct representation in atmospheric models requires an understanding of the microscopic processes leading to ice nucleation. A key parameter in the theoretical description of ice nucleation is the activation energy, which controls the flux of water molecules from the bulk of the liquid to the solid during the early stages of ice formation. In most studies it is estimated by direct association with the bulk properties of water, typically viscosity and self-diffusivity. As the environment in the ice-liquid interface may differ from that of the bulk, this approach may introduce bias in calculated nucleation rates. In this work a theoretical model is proposed to describe the transfer of water molecules across the ice-liquid interface. Within this framework the activation energy naturally emerges from the combination of the energy required to break hydrogen bonds in the liquid, i.e., the bulk diffusion process, and the work dissipated from the molecular rearrangement of water molecules within the ice-liquid interface. The new expression is introduced into a generalized form of classical nucleation theory. Even though no nucleation rate measurements are used to fit any of the parameters of the theory the predicted nucleation rate is in good agreement with experimental results, even at temperature as low as 190 K, where it tends to be underestimated by most models. It is shown that the activation energy has a strong dependency on temperature and a weak dependency on water activity. Such dependencies are masked by thermodynamic effects at temperatures typical of homogeneous freezing of cloud droplets; however, they may affect the formation of ice in haze aerosol particles. The new model provides an independent estimation of the activation energy and the homogeneous ice nucleation rate, and it may help to improve the interpretation of experimental results and the development of parameterizations for cloud formation.

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Homogeneous Condensation—Freezing Nucleation Rate Measurements for Small Water Droplets in an Expansion Cloud Chamber

Cited by 84 publications

References 0 publications

Parameterizing ice nucleation rates using contact angle and activation energy derived from laboratory data

Parameterizing ice nucleation rates using contact angle and activation energy derived from laboratory data

Does the Homogeneous Ice Nucleation Initiate in the Bulk Volume or at the Surface of Super-Cooled Water Droplets? A Review

Thermodynamic derivation of the activation energy for ice nucleation

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