Karman vortices downstream of the Kurils

Karman vortices downstream of the Kurils

In meteorology, gases and liquids are considered continuous media (fluids), and the corresponding physical processes in the atmosphere are governed by the laws of fluid dynamics. Cloud formations provide a clear visualization of highly complex processes of flow, wave formation, turbulence, and mixing.
Sequences of vortices, which form when air flows around relatively small obstacles, are known as von Kármán vortex streets. Behind the obstacles, vortices are periodically shed, forming two staggered rows with the direction of rotation opposite in each row. The characteristic scale of the vortex streets depends on the dimensions of the obstacle interacting with the flow. Such phenomena are typically described using the Reynolds number, which is a dimensionless parameter expressing the ratio of inertial to viscous forces within the flow. Von Kármán vortex streets only occur within a specific range of Reynolds numbers.
In this case, multiple vortex streets can be observed forming downstream of the Kuril Islands. A cyclonic low-pressure system (with a central pressure of 983 hPa and wind speeds up to 90 km/h) is located approximately 1,500 km southeast of the island chain and is “sucking” air masses from the Sea of Okhotsk at speeds of around 30-40 km/h through the straits between the islands.
The extensive field of low-altitude closed convective cloud cells formed as cold continental air was carried over the comparatively warm waters of the North Pacific. This is leading to a strong thermal contrast between the air and to the sea and to convective instability. The cloud field acts as a passive tracer of atmospheric flow, making the vortex-shedding processes and resulting von Kármán vortex streets clearly visible.

Further reading

Karman Vortex (Cloud Structures, Brockmann Consult)
Kármán vortex street (Wikipedia)
Vortex Variety Hour (NASA Science)
Earth from Orbit: von Kármán Vortices (NOAA NESDIS)