Growth of Cloud Droplets in a Turbulent Environment

• Wojciech W. Grabowski ^[1] ; Lian-Ping Wang ^[2]
  1. [1] National Center for Atmospheric Research

     National Center for Atmospheric Research

     Estados Unidos

     
  2. [2] University of Delaware

     University of Delaware

     Estados Unidos

     
• Localización: Annual review of fluid mechanics, ISSN 0066-4189, Nº. 45, 2013, págs. 293-324
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • Motivated by the need to resolve the condensation-coalescence bottleneck in warm rain formation, a significant number of studies have emerged in the past 15 years concerning the growth of cloud droplets by water-vapor diffusion and by collision-coalescence in a turbulent environment. With regard to condensation, recent studies suggest that small-scale turbulence alone does not produce a significant broadening of the cloud-droplet spectrum because of the smearing of droplet-scale fluctuations by rapid turbulent and gravitational mixing. However, different diffusional-growth histories associated with large-eddy hopping could lead to a significant spectral broadening. In contrast, small-scale turbulence in cumulus clouds makes a significant contribution to the collision-coalescence of droplets, enhancing the collection kernel up to a factor of 5, especially for droplet pairs with a low gravitational collision rate. This moderate level of enhancement has a significant impact on warm rain initiation. The multiscale nature of turbulent cloud microphysical processes and open research issues are delineated throughout.