Ordered arrangement of clouds
These are weakly formed gravity clouds or density clouds. Clouds are formed from condensation, which is just tiny water (and other gases) droplets and vapor. As such, these tiny droplets and vapors will flow like ripples on the surface of water in a slow breeze. What you're seeing here is light-action wave ripples in the atmosphere and the resulting effect on the tiny droplets, is a wave-like or ripple-like pattern.