Due to an interplay between hydrodynamics and ring topology, the BR molecules tumble around the gradient direction, which is perpendicular to the vorticity and flow axes.
On the contrary, PCs become thin, orient themselves close to the flow axis and maintain a fixed, stretched and non-tumbling conformation under shear.
Pincho says... Liquids follow the rules of dimensional physics for X/Y/Z as mechanics... Supercell Storm Discovery
Which are observed in many ways...
Buoyancy Wave mechanics Snowflakes Raindrops Gravity Air Electrons