Homogeneous nucleation rates of supercooled water measured in single levitated microdroplets

1999 ◽  
Vol 111 (14) ◽  
pp. 6521-6527 ◽  
Author(s):  
B. Krämer ◽  
O. Hübner ◽  
H. Vortisch ◽  
L. Wöste ◽  
T. Leisner ◽  
...  
Keyword(s):  
Homogeneous Nucleation ◽  
Supercooled Water

scholarly journals Comment on evidence for surface-initiated homogeneous nucleation

2003 ◽  
Vol 3 (5) ◽  
pp. 1439-1443 ◽  
Author(s):  
J. E. Kay ◽  
V. Tsemekhman ◽  
B. Larson ◽  
M. Baker ◽  
B. Swanson
Keyword(s):  
Homogeneous Nucleation ◽  
Laboratory Experiments ◽  
Drop Size ◽  
Supercooled Water ◽  
Ice Nucleation ◽  
Surface Nucleation ◽  
Embryo Formation ◽  
Atmospheric Data ◽  
Water Drops

Abstract. We investigate theoretical, laboratory, and atmospheric evidence for a recently proposed hypothesis: homogeneous ice nucleation initiates at the surface, not in the volume, of supercooled water drops. Using existing thermodynamic arguments, laboratory experiments, and atmospheric data, we conclude that ice embryo formation at the surface cannot be confirmed or disregarded. Ice nucleation rates measured as a function of drop size in an air ambient could help distinguish between volume and surface nucleation rates.

scholarly journals Modelling the effect of condensed-phase diffusion on the homogeneous nucleation of ice in supercooled water

2019 ◽  
Author(s):  
Kathryn Fowler ◽  
Paul Connolly ◽  
David Topping
Keyword(s):  
Low Temperature ◽  
Aerosol Particle ◽  
Condensed Phase ◽  
Homogeneous Nucleation ◽  
Supercooled Water ◽  
Organic Aerosol ◽  
Ice Nucleation ◽  
Cirrus Clouds ◽  
Climate Modelling ◽  
Phase Diffusion

Abstract. In-situ studies of low temperature cirrus clouds have found unexpectedly low ice crystal numbers and consistently high supersaturations, which suggest that our understanding of the freezing mechanisms under these conditions are incomplete. Computational models typically use homogeneous nucleation to predict the ice nucleated in supercooled water. However, the existence of ultra-viscous organic aerosol in the upper troposphere has offered alternative ice nucleation pathways, which have been observed in laboratory studies. The possible effects of aerosol viscosity on cloud micro-physical properties have traditionally been interpreted from simple model simulations of an individual aerosol particle based on equilibration timescales. In this study, to gain insight into the formation of ice in low temperature cirrus clouds, we have developed the first cloud parcel model with bin micro-physics to simulate condensed phase diffusion through each individual aerosol particle. Our findings demonstrate, for the first time, the complex relationship between the rate of ice formation and the viscosity of secondary organic aerosol, driven by two competing effects – which cannot be explained using existing modelling approaches. The first is inhibition of homogeneous ice nucleation below 200 K, due to restricted particle growth and low water volume. The second occurs at temperatures between 200 K and 220 K, where water molecules are slightly more mobile and a layer of water condenses on the outside of the particle, causing an increase in the number of frozen aerosol particles. Our new model provides a basis to better understand and simulate cirrus cloud formation on a larger scale, addressing a major source of uncertainty in climate modelling through the representation of cloud processes.

The spontaneous nucleation of supercooled water

1952 ◽  
Vol 215 (1120) ◽  
pp. 65-66 ◽  
Keyword(s):  
Activation Energy ◽  
Homogeneous Nucleation ◽  
Critical Size ◽  
Freezing Point ◽  
Pure Water ◽  
Supercooled Water ◽  
Absolute Temperature ◽  
Specific Surface Energy ◽  
Spontaneous Nucleation ◽  
Self Diffusion

A number of experimenters have reported on the possibility of supercooling small droplets of pure water ( r < 10 μ ) to about – 40° C before freezing occurs. As foreign nuclei are excluded it seems that aggregates of the ice phase must be formed by chance associations of the molecules in the supercooled water (i. e. homogeneous nucleation). An expression for rate of production of nuclei of critical size, J cm -3 s -1 , has been given by Turnbull & Fisher (1949), and in the case of ice, may be written (Mason 1952) log J = 32.84 + log T - U /2.303 kT – 760 σ 3 /( T 0 – T ) 2 T ' where U is the activation energy for self-diffusion of a molecule in the liquid, σ the specific surface energy of the crystal-liquid interface, T the absolute temperature, and T 0 (= 273° K) the thermodynamic freezing-point.

scholarly journals Theoretical analysis of crystallization by homogeneous nucleation of water droplets

2019 ◽  
Vol 21 (5) ◽  
pp. 2410-2418 ◽  
Author(s):  
Kyoko K. Tanaka ◽  
Yuki Kimura
Keyword(s):  
Theoretical Analysis ◽  
Homogeneous Nucleation ◽  
Crystallization Process ◽  
Supercooled Water ◽  
Water Droplets ◽  
Novel Method

We propose a novel method for analyzing the crystallization process from supercooled water droplets.

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