Satellite swirls: Vortex streets off the Canary Islands

An impressive weather phenomenon recently occurred off the Canary Islands, but it can only be observed from space.

What was invisible from the ground was a spectacular sight seen from space. These Von Kármán vortex streets formed in the Canaries as a repeating pattern of swirling vortices.

Suitable conditions on the leeward side of small, but mountainous islands are needed for their formation. In this case, a strong north-east trade wind was the trigger for these special cloud forms.

When the wind flows around the high altitude volcanoes of the Canary Islands, two counter-rotating air vortices form downwind, which oscillate back and forth at regular intervals. The clouds follow the air flow and make these vortices visible.

Their appearance depends on land topography and wind speed. If the wind is too weak, the air flow merges again without turbulence. If turbulence is too strong, more chaotic swirls occur instead of a symmetrical vortex street.

The most pronounced vortex streets were in the lee of La Palma and Gran Canaria, where topography is ideal with volcanoes over 2000 m high. Tenerife, El Hierro and La Gomera also had smaller, but still pronounced vortices.

Fuerteventura and Lanzarote, on the other hand, are much flatter so no cloud vortices formed here.