Most think a raindrop has the shape of a tear drop, but in actuality, raindrops start off as a sphere. As they fall, and move through the air, the raindrop will turn more into a hamburger shape. This is due to the flow of air around the drop.
Sometimes raindrops will catch up together and join together as they fall. Once they get to heavy, they will split into multiple raindrops again.
Most raindrops are between .5 mm to 4.0 mm in size.