  This article discusses a potential impact of turbulent velocity fluctuations
of the air on a drizzle formation in Cumulus clouds. Two different
representations of turbulent velocity fluctuations for a microphysics
formulated in a Lagrangian framework are discussed - random walk model and the
interpolation, and its effect on microphysical properties of the cloud
investigated.
  Turbulent velocity fluctuations significantly enhances velocity differences
between colliding droplets, especially those having small sizes. As a result
drizzle forms faster in simulations including a representation of turbulence.
Both representations of turbulent velocity fluctuations, random walk and
interpolation, have similar effect on droplet spectrum evolution, but
interpolation of the velocity does account for a possible anisotropy in the air
velocity.
  All discussed simulations show relatively large standard deviation
($\sim$1${\mu}m$) of the cloud droplet distribution from the onset of cloud
formation is observed. Because coalesence processes aerosol inside cloud
droplets, detail information about aerosol is available. Results from numerical
simulations show that changes in aerosol spectrum due to aerosol processing
during droplet coalescence are relatively small during $\sim$20 min. of the
cloud evolution simulated with numerical model.
  Drizzle forms initially near the cloud edge, either near the cloud top, where
the mass of water is the largest, or near the entrainment eddies.
