The weight of the droplet is also small so that slight upward air currents can easily suspend the droplet and allow it to evaporate as it falls slowly through the drier atmosphere below. Relate the concept of acceleration due to gravity to the terminal velocity of the raindrops. Describe how the process of collision and coalescence produces precipitation. Warm clouds form above the freezing point of water. Precipitation is formed by collisions.
Larger droplets fall faster than smaller droplets due to a greater terminal velocity.
It is the larger droplet falling through the smaller ones that grows by coalescing. Coalescence is enhanced when colliding drops have opposite electric charge. Size is also enhanced by the time a falling drop spends in a cloud. Thick clouds with strong vertical updrafts form the largest drops. A warm towering cumulus congestus because the strong updrafts increase the time spent in colliding and coalescing.