Strange 'Cloud Streets' in Warsaw, Poland - April 18, 2012

"'Cloud streets' are created when convection currents cut low-lying cumulus into long, clean strips."

Horizontal convective rolls, also known as horizontal roll vortices or cloud streets, are long rolls of counter-rotating air that are oriented approximately parallel to the ground in the planetary boundary layer.

Horizontal convective rolls are counter-rotating vortex rolls that are nearly aligned with the mean wind of the convective boundary layer.



Another video example of a "Cloud Street".



Source: Sheilaaliens