small raindrop
Area swept is
smaller
than area of
drop Collision-Coalescence
Big
water drops fall faster than small drops
As big drops fall, they collide with smaller drops
Some of the smaller drops stick to the big drops
As big drops fall, they collide with smaller drops
Some of the smaller drops stick to the big drops
Collision-Coalescence
Drops can grow by this process in warm clouds with
no iceOccurs in warm tropical clouds
Collection
Efficiency 10-50%