@article {1382,
	title = {Deposition ice nucleation on soot at temperatures relevant for the lower troposphere},
	journal = {Journal of Geophysical Research-Atmospheres},
	volume = {111},
	number = {D4},
	year = {2006},
	note = {ISI Document Delivery No.: 021EPTimes Cited: 36Cited Reference Count: 43},
	month = {Feb},
	pages = {9},
	type = {Article},
	abstract = {The ice nucleating efficiency of many important atmospheric particles remains poorly understood. Here we investigate the ice nucleation properties of a range of soot types including soot that has been treated with atmospherically relevant amounts of ozone. We focus on deposition nucleation below water saturation and at temperatures ranging from 243 to 258 K. For our experimental conditions, ice nucleation never occurred at temperatures above 248 K and below water saturation. Below 248 K, ice occasionally formed in our experiments with no indication of the formation of water droplets prior to ice formation. However, even at these temperatures the relative humidity with respect to ice (RHi) was close to water saturation when ice nucleation was observed, suggesting water nucleation may have occurred first followed by ice nucleation during the condensation process. We also performed a complimentary set of experiments where we held soot particles at 248 K and RHi = 124 +/- 4\%, which is just below water saturation, for a period of 8 hours. From these measurements we calculated an upper limit of the heterogeneous ice nucleation rate coefficient of 0.1 cm(-2) s(-1). If the number of soot particles is 1.5 x 10(5) L-1 in the atmosphere ( which corresponds to urban-influenced rural areas), then the number of ice particles produced below water saturation at these conditions is at most 0.1 particles L-1 on the basis of our upper limit. We conclude from our studies that deposition nucleation of ice on most types of soot particles is not important in the Earth{\textquoteright}s troposphere above 243 K and below water saturation.},
	keywords = {ACID, AEROSOL, CARBON, CLOUDS, crystallization, CRYSTALS, deliquescence, EXHAUST, PARTICLES, WATER},
	isbn = {0148-0227},
	url = {<Go to ISI>://000235966800008},
	author = {Dymarska, M. and Murray, B. J. and Sun, L. M. and Eastwood, M. L. and Knopf, D. A. and Bertram, A. K.}
}
@article {1218,
	title = {The formation of cubic ice under conditions relevant to Earth{\textquoteright}s atmosphere},
	journal = {Nature},
	volume = {434},
	number = {7030},
	year = {2005},
	note = {ISI Document Delivery No.: 904JUTimes Cited: 61Cited Reference Count: 30},
	month = {Mar},
	pages = {202-205},
	type = {Article},
	abstract = {An important mechanism for ice cloud formation in the Earth{\textquoteright}s atmosphere is homogeneous nucleation of ice in aqueous droplets, and this process is generally assumed to produce hexagonal ice(1,2). However, there are some reports that the metastable crystalline phase of ice, cubic ice, may form in the Earth{\textquoteright}s atmosphere(3-5). Here we present laboratory experiments demonstrating that cubic ice forms when micrometre-sized droplets of pure water and aqueous solutions freeze homogeneously at cooling rates approaching those found in the atmosphere. We find that the formation of cubic ice is dominant when droplets freeze at temperatures below 190 K, which is in the temperature range relevant for polar stratospheric clouds and clouds in the tropical tropopause region. These results, together with heat transfer calculations, suggest that cubic ice will form in the Earth{\textquoteright}s atmosphere. If there were a significant fraction of cubic ice in some cold clouds this could increase their water vapour pressure, and modify their microphysics and ice particle size distributions(5). Under specific conditions this may lead to enhanced dehydration of the tropopause region(5).},
	keywords = {CHEMISTRY, CLOUDS, crystallization, HALO, LIQUID WATER, MICROPHYSICS, NUCLEATION, PHASE-TRANSITIONS, X-RAY-DIFFRACTION},
	isbn = {0028-0836},
	url = {<Go to ISI>://000227494500041},
	author = {Murray, B. J. and Knopf, D. A. and Bertram, A. K.}
}
