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Unravelling the microphysics of polar mesospheric cloud formation

Duft, Denis; Nachbar, Mario; Leisner, Thomas

Abstract:
Polar mesospheric clouds are the highest water ice clouds occurring in the terrestrial atmosphere. They form in the polar summer mesopause, the coldest region in the atmosphere. It has long been assumed that these clouds form by heterogeneous nucleation on meteoric smoke particles which are the remnants of material ablated from meteoroids in the upper atmosphere. However, until now little was known about the properties of these nanometre-sized particles and application of the classical theory for heterogeneous ice nucleation was impacted by large uncertainties. In this work, we performed laboratory measurements on the heterogeneous ice formation process at mesopause conditions on small (r=1 to 3 nm) iron silicate nanoparticles serving as meteoric smoke analogues. We observe that ice growth on these particles sets in for saturation ratios with respect to hexagonal ice below Sh=50, a value that is commonly exceeded during the polar mesospheric cloud season, affirming meteoric smoke particles as likely nuclei for heterogeneous ice formation in mesospheric clouds. We present a simple ice-activation model based on the Kelvin–Thomson equation that takes into account the water coverage of iron silicates of various compositions. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000094271
Veröffentlicht am 08.05.2019
Originalveröffentlichung
DOI: 10.5194/acp-19-2871-2019
Scopus
Zitationen: 2
Web of Science
Zitationen: 2
Coverbild
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung - Atmosphärische Aerosolforschung (IMK-AAF)
Publikationstyp Zeitschriftenaufsatz
Jahr 2019
Sprache Englisch
Identifikator ISSN: 1680-7324
KITopen-ID: 1000094271
HGF-Programm 12.04.02 (POF III, LK 01)
Erschienen in Atmospheric chemistry and physics
Band 19
Heft 5
Seiten 2871–2879
Bemerkung zur Veröffentlichung Gefördert durch den KIT-Publikationsfonds
Vorab online veröffentlicht am 06.03.2019
Nachgewiesen in Scopus
Web of Science
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