Complex sentence: If the vortex's expansion is obstructed and symmetry is broken, the vortex breaks into a sickle form, still invisible, and because of the central and surface tension-forces it shrinks through an intermediate state of a cylinder and finally into a ball.
Split into simpler sentences: If the vortex's expansion is obstructed, and symmetry is broken, the vortex will break into cyclical form. Still invisible, and due to the central and surface tension-forces, it shrinks to an intermediate state of a cylinder, and finally into a ball.