%0 Journal Article
%T Aerosol Scavenging during the Early Growth Stage of Ice Crystal Formation
%A Gianni Santachiara
%A Matteo Piazza
%A Franco Belosi
%J Atmospheric and Climate Sciences
%P 395-409
%@ 2160-0422
%D 2018
%I Scientific Research Publishing
%R 10.4236/acs.2018.84026
%X This paper
investigated the possibility that aerosol particles are scavenged during the
first and fast diffusional growth of small ice crystals. After ice phase
formation, riming, scavenging and aggregation may lead to the collection of
additional aerosol particles. Therefore, particles left after ice evaporation
in hydrometeors, called ice residuals, may not currently be identical to ice
nucleating particles. To overcome this problem, the largest ice crystals are
removed during sampling in clouds and only crystals in the initial phase of
growth, with diameters lower than 20 - 30 ¦Ìm, are usually
considered. Published papers assume that no aerosol scavenging takes place
during the initial phase of growth of small ice crystals. The aim of this paper
was to ascertain if this assumption is valid. Experiments were performed in a
cold laboratory by considering ice crystals growing in the presence of
supercooled droplets. Results showed that crystals can scavenge aerosol even in
the first stage of growth. Theoretical considerations show that aerosol
scavenging cannot be <span>explained by Brownian
diffusion, inertial impaction or interception </span>processes. We suggest that
the presence of aerosol in the pristine ice crystals may be due to
diffusiophoretic force. During diffusive crystal growth, a flow called Stefan¡¯s
flow exists near the hydrometeor surface, driving the nearby aerosol particles
towards the surface of the growing hydrometeors.
%K Ice Crystals
%K Ice Nucleating Particles
%K Aerosol Scavenging
%K Diffusiophoresis
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=87795