Homogeneous Nucleation of Water Vapor Determined by Scattering of a Laser Beam

1966 ◽  
Vol 44 (8) ◽  
pp. 3132-3133 ◽  
Author(s):  
B. G. Schuster ◽  
W. B. Good
Keyword(s):  
Water Vapor ◽  
Laser Beam ◽  
Homogeneous Nucleation

How does a Homogeneous Nucleation Event respond to changes of Parameterizations of Water Activity and Saturation Vapor Pressure?

2021 ◽  
Author(s):  
Manuel Baumgartner ◽  
Martina Krämer ◽  
Christian Rolf
Keyword(s):  
Water Vapor ◽  
Water Activity ◽  
Nucleation Rate ◽  
Homogeneous Nucleation ◽  
Saturation Pressure ◽  
Cirrus Clouds ◽  
Ice Crystals ◽  
Nucleation Theory ◽  
Ice Microphysics ◽  
Water Vapor Saturation Pressure

<p>Homogeneous nucleation of ice crystals via freezing of small supercooled solution particles represents a major pathway in the formation of cirrus clouds with high ice water content at low temperatures. A reasonable physical explanation of this type of freezing is provided by Koop's nucleation theory, relating the homogeneous nucleation rate to the water activity of the solution particles. While the homogeneous nucleation rate encodes the probability of freezing of solution particles, the water activity represents the ratio of water vapor saturation pressures over the solution to that over pure water in Koop's portrayal.</p><p>By using the ice microphysics model "CLaMS-Ice", we investigate the effect of various formulations of the water activity and the water vapor saturation pressure on the resulting cirrus clouds. Although CLaMS-Ice is a two-moment bulk model, it implements a comparatively detailed ice microphysics formulated by Spichtinger and Gierens. Such a microphysics scheme is suitable to be implemented in full three dimensional atmospheric models in contrast to even more detailed bin microphysics schemes.</p><p>We performed sensitivity simulations over a wide range of temperatures and vertical velocities by using two different direct parameterizations of water activity based on thermodynamic models in addition to the one used by Koop. Also, three different formulations of the water vapor saturation pressure are applied in the simulations. The results are evaluated regarding the predicted number of ice crystals and the ice onset humidities. In particular, one major finding is that the freezing thresholds are increased compared to Koop's freezing lines.</p>

scholarly journals Thermodynamics of homogeneous nucleation of ice particles in the polar summer mesosphere

2009 ◽  
Vol 9 (3) ◽  
pp. 965-971 ◽  
Author(s):  
A. Y. Zasetsky ◽  
S. V. Petelina ◽  
I. M. Svishchev
Keyword(s):  
Water Vapor ◽  
Homogeneous Nucleation ◽  
Water Clusters ◽  
Critical Size ◽  
Summer Temperature ◽  
Nano Particles ◽  
Vapor Density ◽  
Water Ice ◽  
Formation Pathway ◽  
Hexagonal Ice

Abstract. We present the hypothesis of homogeneous nucleation of ice nano-particles in the polar summer mesosphere. The nucleation of condensed phase is traced back to the first step on the formation pathway, which is assumed to be the transition of water vapor to amorphous cluster. Amorphous clusters then freeze into water ice, likely metastable cubic ice, when they reach the critical size. The estimates based on the equilibrium thermodynamics give the critical size (radius) of amorphous water clusters as about 1.0 nm. The same estimates for the final transition step, that is the transformation of cubic to hexagonal ice, give the critical size of about 15 nm at typical upper mesospheric conditions during the polar summer (temperature T=150 K, water vapor density ρvapor=109 cm−3).

Homogeneous nucleation rate measurements in supersaturated water vapor II

2009 ◽  
Vol 131 (7) ◽  
pp. 074507 ◽  
Author(s):  
David Brus ◽  
Vladimír Ždímal ◽  
Hermann Uchtmann
Keyword(s):  
Water Vapor ◽  
Nucleation Rate ◽  
Homogeneous Nucleation

Homogeneous nucleation of water vapor

1974 ◽  
Vol 48 (3) ◽  
pp. 508-511 ◽  
Author(s):  
W.G Courtney ◽  
D.R Forshey ◽  
J.B Greenshields
Keyword(s):  
Water Vapor ◽  
Homogeneous Nucleation
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