Homogeneous Nucleation Rate for Highly Supercooled Cirrus Cloud Droplets

Sassen, Kenneth; Dodd, Gregory C.

doi:10.1175/1520-0469(1988)045<1357:hnrfhs>2.0.co;2

Cited by 168 publications

(144 citation statements)

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“…Sassen and Dodd (1988) formulated a parameterization of homogeneous freezing of solution droplets at cirrus condition, based on earlier observations that the median homogeneous freezing temperatures of emulsified drops were depressed by solutes to an even greater extent than the lowering of the melting point, so that…”

Section: Freezing Point Depression and Water Activity Parameterizationsmentioning

confidence: 55%

Ice nucleation by surrogates for atmospheric mineral dust and mineral dust/sulfate particles at cirrus temperatures

Archuleta

DeMott²,

Kreidenweis³

2005

Atmos. Chem. Phys.

276

377

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Abstract. This study examines the potential role of some types of mineral dust and mineral dust with sulfuric acid coatings as heterogeneous ice nuclei at cirrus temperatures. Commercially-available nanoscale powder samples of aluminum oxide, alumina-silicate and iron oxide were used as surrogates for atmospheric mineral dust particles, with and without multilayer coverage of sulfuric acid. A sample of Asian dust aerosol particles was also studied. Measurements of ice nucleation were made using a continuous-flow icethermal diffusion chamber (CFDC) operated to expose sizeselected aerosol particles to temperatures between −45 and −60 • C and a range of relative humidity above ice-saturated conditions. Pure metal oxide particles supported heterogeneous ice nucleation at lower relative humidities than those required to homogeneously freeze sulfuric acid solution particles at sizes larger than about 50 nm. The ice nucleation behavior of the same metal oxides coated with sulfuric acid indicate heterogeneous freezing at lower relative humidities than those calculated for homogeneous freezing of the diluted particle coatings. The effect of soluble coatings on the ice activation relative humidity varied with the respective uncoated core particle types, but for all types the heterogeneous freezing rates increased with particle size for the same thermodynamic conditions. For a selected size of 200 nm, the natural mineral dust particles were the most effective ice nuclei tested, supporting heterogeneous ice formation at an ice relative humidity of approximately 135%, irrespective of temperature. Modified homogeneous freezing parameterizations and theoretical formulations are shown to have application to the description of heterogeneous freezing of mineral dust-like particles with soluble coatings.

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Section: Freezing Point Depression and Water Activity Parameterizationsmentioning

confidence: 55%

Ice nucleation by surrogates for atmospheric mineral dust and mineral dust/sulfate particles at cirrus temperatures

Archuleta

DeMott²,

Kreidenweis³

2005

Atmos. Chem. Phys.

276

377

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“…For example, upper tropospheric aerosols are thought to play a role in heterogeneous ( chemistry Hu and Abbatt 1997;Lary et al ) 1997 , in midlatitude ozone depletion ( ) Solomon et al 1997 , in climate forcing ( ) Charlson et al 1992;Pandis et al 1995 , ( and in cirrus cloud formation DeMott and Rogers 1990; Sassen and Dodd 1988; ) Tabazadeh et al 1997 . To characterize the role of particles in the atmosphere, there is a need for laboratory experiments on model aerosols.…”

Section: Introductionmentioning

confidence: 99%

Design and Characterization of a Fluidized Bed Aerosol Generator: A Source for Dry, Submicrometer Aerosol

Prenni¹,

Siefert²,

Onasch³

et al. 2000

Aerosol Science and Technology

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ABSTRACT. A uidized bed aerosol generator has been designed and built for the purpose of generating a constant output of dry, submicrometer particles with a large number density. The output of the uidized bed for generating aerosol particles from dry soot powder has been characterized using a differential mobility analyzer and a condensation particle counter. The particle size distribution is bimodal, with a mode in the submicrometer diameter size range and a mode in the supermicrometer diameter size range. The larger diameter mode is fully separated from the smaller mode and can thus be easily removed from the aerosol ow using impaction techniques. The distribution in the submicrometer size range is nearly log-normal, with a count median diameter falling between 0.1 and 0.3 micrometers. A number density of ) 10 5 particles cm I 3 of soot particles in the submicrometer ( ) range can be produced, constant to within 25% 1 standard deviation over a 4 h time period. The number density of particles produced in the submicrometer range was found to vary with the ratio of soot to bronze beads in the bed mixture, whether or not a feed system was used, and nitrogen ow rate through the uidized bed and feed system.

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“…Further, it is expected that we could reduce the noise level, hence S/N ratio, of detected signal by more than one order of magnitude by the use of a Lock-in amplifier (this type of amplifier is useful equipment to detect the objective signal buried in random noises by the integration of signals). Since the model predicted that the value of liquid water in the convective region near the cloud base is about 0.05 mg/cm2 in terms of liquid water path (Sassen and Dodd, 1988), these water droplets may be detectable by use of the microwave telescope equipped with this type of amplifier.…”

Section: Discussionmentioning

confidence: 99%

“…These models indicate that the dominant process which controls the freezing of the supercooled water droplets is homogeneous nucleation. Sassen and Dodd (1988) evaluated the homogeneous nucleation rate to account for the vertical profiles of the concentrations of the droplets and crystals observed near the cloud base by in situ measurements. However, the evaluated value is very large compared with that c1992, Meteorological Society of Japan predicted by classical theory, but very small compared with that of laboratory measurements.…”

Section: Introductionmentioning

confidence: 99%

Utilization of the 4m Microwave Telescope for the Measurement of Liquid Water Path in Cirrus Clouds

Imasu¹,

Iwasaka

1992

Journal of the Meteorological Society of Japan

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Homogeneous Nucleation Rate for Highly Supercooled Cirrus Cloud Droplets

Cited by 168 publications

References 0 publications

Ice nucleation by surrogates for atmospheric mineral dust and mineral dust/sulfate particles at cirrus temperatures

Ice nucleation by surrogates for atmospheric mineral dust and mineral dust/sulfate particles at cirrus temperatures

Design and Characterization of a Fluidized Bed Aerosol Generator: A Source for Dry, Submicrometer Aerosol

Utilization of the 4m Microwave Telescope for the Measurement of Liquid Water Path in Cirrus Clouds

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