V. Stoyanova et al., FREEZING OF WATER DROPLETS SEEDED WITH ATMOSPHERIC AEROSOLS AND ICE NUCLEATION ACTIVITY OF THE AEROSOLS, Journal of aerosol science, 25(5), 1994, pp. 867-877
A method is proposed for analysing the kinetics of droplet freezing, w
hich makes it possible to determine the nucleation rate from the tempe
rature derivative of the logarithm of the relative number of unfrozen
droplets. Experiments were carried out by freezing droplets of distill
ed water either unseeded or seeded with aerosol dust, and by employing
this method the ice nucleation rate was determined. It was found that
while in the unseeded droplets ice nucleation is controlled by only o
ne type of nucleation-active centre, in the seeded droplets it is stim
ulated by the presence of three new types of active centres introduced
by the aerosol seeds. Each type of active centre is characterized qua
ntitatively by an activity factor and a corresponding ''wetting'' angl
e. The theoretically expected linear dependence of the nucleation rate
on the concentration of aerosol seeds is experimentally confirmed and
the relative number of the aerosol-introduced active centres is calcu
lated.