Impact of turbulence on cloud microphysics of water droplets population

This work focuses on the turbulent shear-less mixing structure of a cloud/clear-air interface with physical parameters typical of cumulus warm clouds. We investigate the effect of turbulence on the droplet size distribution, in particular we focus on the distribution’s broaden- ing and on the collision kernel. We performed numerical experiments via Direct Numerical Simulations (DNS) of turbulent interfaces sub- ject to density stratification and vapor density fluctuation. Specifically, an initial super-saturation around 2% and a dissipation rate of turbu- lent kinetic energy of 100 $cm{^2}$/$s{^3}$ are set in the DNSs. The Taylor’s Reynolds number is between 150 and 300. The total number of par- ticles is around 5-10 millions, matching an initial liquid water content of 0.8 g/$m{^3}$ . Through these experiments, we provide a measure of the kernel of collisional integral operators to be compared with literature models [Saffman Turner, 1955] and possibly used inside drops Population Balance Equations (PBE) that include both processes of drops’ growth by condensation/evaporation and aggregation.