On Thursday, a pinhole eye appeared on imagery from a variety of satellites off the coast of California. With a lack of meteorological context, the swirl appears as a small hurricane. Fear not, Californians, this feature is a mere vortex embedded in a harmless stratocumulus cloud deck. So how did this hurricane-looking feature form?
(via MODIS-Aqua & NASA Worldview)
It's a called a "von Kármán vortex". It forms when air is diverted around an object that sticks up above the plane of a surface. In this case, the air was forced around the hilly terrain of San Clemente Island. As air moved southeasterly, the island forced the air around it causing the wind to change speed and direction. As the wind changes speed and direction it can begin to rotate as seen in the gif below.
(via GOES-East & COD Meteorology)
This phenomenon happens with or without clouds present but the clouds to provide gorgeous illustrations for the human eye. In a stroke of luck, a U.S. Marine was flying an F18 Hornet off the coast of San Diego. Sure enough, he got the shot and it's mind blowing.
These vortices are fairly common in certain places around the world including the Canary Islands off the western coast of Africa. In the case below, the wind direction was persistent enough to cause many vortices in a row. The result is beautiful.
(via NASA Earth Observatory)