Surface Tension
One day I was ironing some clothes and noticed some water droplets on the board. I took this picture to demonstrate that blood, although different from water will form a sphere due to cohesive forces. Cohesive forces as in the attraction of like molecules to each other.
A paper-clip floating on water due to surface tension.
A water bug walking on the water due to surface tension.
Blood drops in flight will oscillate, but will quickly damp and form a sphere. Damping time has been determined to be 0.05 sec for a typical drop of .05 ml.
