Particle Clustering in Turbulence: Implications for Early Cloud Development 
(Prof. Lance Collins, Cornell University in collaboration with the International
Centre for Turbulence Research).  Improved upon current microphysical
models, which predict condensational growth and cloud droplet
distributions far slower and narrower than observed.  In summary, the
role of turbulence in clouds is to enhance the collision and
coalescence rate of cloud droplets; to cause macroscopic mixing of
moist and dry air and microscopic clustering of inertial droplets. 
Clustering in clouds consequently generates fluctuations in
super-saturation of water vapour and increases collision frequency by
1-2 orders of magnitude.  In addition, aerosol particles in a
turbulent flow field preferentially cluster outside of vortices due
to a centrifugal effect, which broadens the drop size distribution
thus accounting for the size gap discrepancy.  Effects of various
fluid parameters upon particle size distribution and evolution were
also considered.  Further study includes additional experiments,
laboratory and field studies, probe of higher Reynolds numbers, and
integration to improve climate models.