Cloud vortices are produced “when air moving over the smooth ocean surface is forced over some obstacle, like an island. The disturbance creates eddies in the air, which have blown the clouds into the pattern seen here. At the center of each eddy is a dark, cloud-free circle, which gets progressively smaller as the turbulence in the air subsides.”
These phenomena are also known as Von Karman vortices. “Von Karman vortices form nearly everywhere that fluid flow is disturbed by an object.”
The images show a cloud vortex swirling behind Jan Mayen Island in the Greenland Sea, another one near Heard Island, in the Indian Ocean and two formed by the winds rushing over the Cape Verde Islands.