The breakup of levitating water drops observed with a high speed camera School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, UK
11 Oct 2011
Received: 06 April 2011 – Published in Atmos. Chem. Phys. Discuss.: 15 April 2011 Abstract. Collision-induced water drop breakup in a vertical wind tunnel was observed
using a high speed camera for interactions between larger drop sizes (up to
7 mm diameter) than have previously been experimentally observed. Three
distinct collisional breakup types were observed and the drop size
distributions from each were analysed for comparison with predictions of
fragment distributions from larger drops by two sets of established
breakup parameterisations. The observations showed some similarities with
both parameterisations but also some marked differences for the breakup
types that could be compared, particularly for fragments 1 mm and smaller.
Modifications to the parameterisations are suggested and examined. Presented
is also currently the largest dataset of bag breakup distributions observed.
Differences between this and other experimental research studies and
modelling parameterisations, and the associated implications for
interpreting results are discussed. Additionally, the stochastic coalescence
and breakup equation was solved computationally using a breakup
parameterisation, and the evolving drop-size distribution for a range of
initial conditions was examined. Initial cloud liquid water content was
found to have the greatest influence on the resulting distribution, whereas
initial drop number was found to have relatively little influence. This may
have implications when considering the effect of aerosol on cloud evolution,
raindrop formation and resulting drop size distributions. Calculations
presented show that, using an ideal initial cloud drop-size distribution,
~1–3% of the total fragments are contributed from collisional
breakup between drops of 4 and 6 mm.
Revised: 19 September 2011 – Accepted: 27 September 2011 – Published: 11 October 2011
Citation: Emersic, C. and Connolly, P. J.: The breakup of levitating water drops observed with a high speed camera, Atmos. Chem. Phys., 11, 10205-10218, doi:10.5194/acp-11-10205-2011, 2011.