How Ambient Pressure Influences Water Droplet Nucleation at Tropospheric Conditions

0349147 - ÚCHP 2011 RIV US eng J - Journal Article
Hyvärinen, A.-P. - Brus, David - Wedekind, J. - Lihavainen, H.
How Ambient Pressure Influences Water Droplet Nucleation at Tropospheric Conditions.
Geophysical Research Letters. Roč. 37, - (2010), L21802. ISSN 0094-8276. E-ISSN 1944-8007
Institutional research plan: CEZ:AV0Z40720504
Keywords : nucleations theories * ambient pressure * condensation of droplets
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 3.505, year: 2010

Nucleation theories typically neglect the influence of the ambient pressure on the condensation of droplets from a supersaturated vapor, despite increasing experimental evidence. We have applied a recently presented model that incorporates this effect to the homogeneous nucleation rates of water at tropospheric conditions. We measured experimental pressure dependent nucleation rates of water in helium at low to intermediate pressures (70-200 kPa) and at temperatures from 240-270 K with the laminar flow diffusion chamber. The observed pressure effect shows a clear positive effect (increasing nucleation rate with increasing pressure) at 270 K and a weaker effect with lower temperatures, consistent with the theory. The experimental pressure effect was more pronounced than predicted by theory. The same principle of the pressure effect should also hold for heterogeneous nucleation of water, which implies that water vapor removal by droplet nucleation of water may be suppressed at tropospheric conditions.
Permanent Link: http://hdl.handle.net/11104/0189462