Question

Why rain drops have less velocity when they touch the ground?

Answer 1

All the rain drops do not fall with a constant velocity. The biggest ones having about 5mm as the diameter have a terminal velocity of about 10m/s and the rain drops of about 0.2mm in diameter touch the ground with a velocity of about 0.1 m/s.

Yes, drops of equal sizes fall approximately with the same terminal velocity. Thus, in actual rainfall, there is a spectrum of velocities with which the rain drops finally touch the ground.

Answer 2

due to wind and atmospheric friction and pressure rain drops aquire low velocity when touching ground..