Life cycle of a droplet

  • Growth by collision

  • the drop initially forms in the updraft of the cloud near cloud base

  • it grows in size by collisions

  • since Vg = w + Vt

    • Vg = ground relative fall speed of the drop
    • w = updraft velocity
    • Vt = drop's terminal velocity
  • then the drop will begin to fall when Vt > w