Freezing of water droplets colliding with kaolinite particles

Erik Anders Svensson; Christophe Eric Ludovic Delval; P J H Freiherr von Und zu Hessberg; Matthew Stanley Johnson; J. B. C. Pettersson

Freezing of water droplets colliding with kaolinite particles

Erik Anders Svensson, Christophe Eric Ludovic Delval, P J H Freiherr von Und zu Hessberg, Matthew Stanley Johnson, J. B. C. Pettersson

Department of Chemistry

25 Citations (Scopus)

Abstract

Contact freezing of single supercooled water droplets colliding with kaolinite dust particles
has been investigated. The experiments were performed with droplets levitated
in an electrodynamic balance at temperatures from 240 to 268 K. Under dry conditions
freezing 5 was observed to occur below 249 K, while a freezing threshold of 267 K was
observed at high relative humidity. The effect of relative humidity is attributed to an
influence on the contact freezing process for the kaolinite-water droplet system, and
it is not related to the lifetime of the droplets in the electrodynamic balance. Freezing
probabilities per collision were derived assuming that collisions at the lowest temper10
ature employed had a probability of unity. The data recorded at high humidity should
be most relevant to atmospheric conditions, and the results indicate that parameterizations
currently used in modelling studies to describe freezing rates are appropriate for
kaolinite aerosol particles. Mechanisms for contact freezing are briefly discussed.

Original language	English
Journal	Atmospheric Chemistry and Physics
Volume	9
Issue number	13
Pages (from-to)	4295-4300
Number of pages	6
ISSN	1680-7316
Publication status	Published - 27 Jan 2009

Cite this

@article{70c0727005c911df825d000ea68e967b,

title = "Freezing of water droplets colliding with kaolinite particles",

abstract = "Contact freezing of single supercooled water droplets colliding with kaolinite dust particleshas been investigated. The experiments were performed with droplets levitatedin an electrodynamic balance at temperatures from 240 to 268 K. Under dry conditionsfreezing 5 was observed to occur below 249 K, while a freezing threshold of 267 K wasobserved at high relative humidity. The effect of relative humidity is attributed to aninfluence on the contact freezing process for the kaolinite-water droplet system, andit is not related to the lifetime of the droplets in the electrodynamic balance. Freezingprobabilities per collision were derived assuming that collisions at the lowest temper10ature employed had a probability of unity. The data recorded at high humidity shouldbe most relevant to atmospheric conditions, and the results indicate that parameterizationscurrently used in modelling studies to describe freezing rates are appropriate forkaolinite aerosol particles. Mechanisms for contact freezing are briefly discussed.",

author = "Svensson, {Erik Anders} and Delval, {Christophe Eric Ludovic} and {Freiherr von Und zu Hessberg}, {P J H} and Johnson, {Matthew Stanley} and Pettersson, {J. B. C.}",

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journal = "Atmospheric Chemistry and Physics",

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TY - JOUR

T1 - Freezing of water droplets colliding with kaolinite particles

AU - Svensson, Erik Anders

AU - Delval, Christophe Eric Ludovic

AU - Freiherr von Und zu Hessberg, P J H

AU - Johnson, Matthew Stanley

AU - Pettersson, J. B. C.

PY - 2009/1/27

Y1 - 2009/1/27

N2 - Contact freezing of single supercooled water droplets colliding with kaolinite dust particleshas been investigated. The experiments were performed with droplets levitatedin an electrodynamic balance at temperatures from 240 to 268 K. Under dry conditionsfreezing 5 was observed to occur below 249 K, while a freezing threshold of 267 K wasobserved at high relative humidity. The effect of relative humidity is attributed to aninfluence on the contact freezing process for the kaolinite-water droplet system, andit is not related to the lifetime of the droplets in the electrodynamic balance. Freezingprobabilities per collision were derived assuming that collisions at the lowest temper10ature employed had a probability of unity. The data recorded at high humidity shouldbe most relevant to atmospheric conditions, and the results indicate that parameterizationscurrently used in modelling studies to describe freezing rates are appropriate forkaolinite aerosol particles. Mechanisms for contact freezing are briefly discussed.

AB - Contact freezing of single supercooled water droplets colliding with kaolinite dust particleshas been investigated. The experiments were performed with droplets levitatedin an electrodynamic balance at temperatures from 240 to 268 K. Under dry conditionsfreezing 5 was observed to occur below 249 K, while a freezing threshold of 267 K wasobserved at high relative humidity. The effect of relative humidity is attributed to aninfluence on the contact freezing process for the kaolinite-water droplet system, andit is not related to the lifetime of the droplets in the electrodynamic balance. Freezingprobabilities per collision were derived assuming that collisions at the lowest temper10ature employed had a probability of unity. The data recorded at high humidity shouldbe most relevant to atmospheric conditions, and the results indicate that parameterizationscurrently used in modelling studies to describe freezing rates are appropriate forkaolinite aerosol particles. Mechanisms for contact freezing are briefly discussed.

M3 - Journal article

SN - 1680-7316

VL - 9

SP - 4295

EP - 4300

JO - Atmospheric Chemistry and Physics

JF - Atmospheric Chemistry and Physics

IS - 13

ER -