This looks like a series of breaking waves, and it's caused by shearing winds -- the wind above the cloud layer and below the cloud layer differ significantly, and in the middle, in between, you get this undulating of the air, and if the difference in those speeds is just right, the tops of the undulations curl over in these beautiful breaking wave-like vortices.
次々と砕ける波頭の形に見えます これは風の力で雲がずれる時に 雲の上側の層と下側の層で 風の速度が異なっていて その間に挟まれた雲の層に 空気のうねりが生じます 互いの速度が うまい具合になると うねりの先端が巻き込まれ 砕ける波の美しい渦が生じます