Title Ice nucleation properties of mineral dust particles; determination of onset RHi, IN active fraction, nucleation time-lag, and the effect of active sites on contact angles
Author Kulkarni, G.; Dobbie, S.
Author Affil Kulkarni, G., University of Leeds, School of Earth and Environment, Leeds, United Kingdom
Source Atmospheric Chemistry and Physics, 10(1), p.95-105, . Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1680- 7316
Publication Date 2010
Notes In English. Published in Atmospheric Chemistry and Physics Discussions: 6 May 2009, http://www.atmos-chem-phys- discuss.net/9/11299/2009/acpd-9-11299- 2009.html ; accessed in May, 2011. 48 refs. GeoRef Acc. No: 310482
Index Terms aerosols; aluminum; climatic change; crystal growth; crystals; dust; experimentation; humidity; ice; ice crystals; metals; minerals; nucleation; nucleation rate; sediments; temperature; Senegal--Dakar; Nigeria; Spain; Africa; alkali metals; alkaline earth metals; atmosphere; calcium; chemical reactions; clastic sediments; climate change; crystallization; Dakar Senegal; Europe; experimental studies; heterogeneous materials; Iberian Peninsula; iron; magnesium; rates; saturation; Senegal; silica; sodium; southeastern Spain; Southern Europe; West Africa
Abstract A newly developed ice nucleation experimental set up was used to investigate the heterogeneous ice nucleation properties of three Saharan and one Spanish dust particle samples. It was observed that the spread in the onset relative humidities with respect to ice (RHi) for Saharan dust particles varied from 104% to 110%, whereas for the Spanish dust from 106% to 110%. The elemental composition analysis shows a prominent Ca feature in the Spanish dust sample which could potentially explain the differences in nucleation threshold. Although the spread in the onset RHi for the three Saharan dust samples were in agreement, the active fractions and nucleation time-lags calculated at various temperature and RHi conditions were found to differ. This could be due to the subtle variation in the elemental composition of the dust samples, and surface irregularities like steps, cracks, cavities etc. A combination of classical nucleation theory and active site theory is used to understand the importance of these surface irregularities on the nucleability parameter, contact angle that is widely used in ice cloud modeling. These calculations show that the surface irregularities can reduce the contact angle by approximately 10 degrees.
URL http://www.atmos-chem-phys.net/10/95/2010/acp-10-95-2010.pdf
Publication Type journal article
Record ID 65007117