Raindrops
Overview
Raindrops are, well, raindrops. They fall from clouds as precipitation, especially those of the nimbus variety.
The Shape of a Raindrop
I learned very recently that the typical shape associated with raindrops is actually very much incorrect. Water droplets falling as precipitation are generally round at small sizes (1-2 mm), and then flatten out on the bottom as they grow larger.
These images are sourced from NASA.