The spherical shape of raindrops is due to
Atmospheric friction of air
The gravity of spherical earth
The surface tension of rainwater
The viscosity of rainwater
The spherical shape of raindrops is due to Surface tension of rainwater
Raindrops start to form in a roughly spherical structure due to the surface tension of water. This surface tension is the "skin" of a body of water that makes the molecules stick together. The cause is the weak hydrogen bonds that occur between water molecules.