Mount Etna, Sicily’s iconic volcano, is renowned for the formation of seemingly perfect smoke rings. Today, it delivered a mesmerizing performance, producing dozens of near perfectly formed rings.
The ‘smoke rings’ of Etna, while appearing as delicate wisps of smoke, are technically vortex rings. A vortex ring is a donut-shaped structure of rotating fluid or gas. In Etna’s case, these rings consist primarily of volcanic gases like water vapor, carbon dioxide, and sulfur dioxide.
Local photographer Maria Liotta captured these stunning photos and shared them with Extreme Pursuit.
The formation of Etna’s vortex rings depends on several factors:
- Gas Velocity: When volcanic gases are expelled from the volcano at high speed, a velocity gradient forms within the gas plume.
- Vent Constriction: A confined vent or narrow conduit within the volcano acts as a bottleneck for the rising gases.
- Friction: The friction between the speeding gases and the vent walls causes the outer edges of the plume to slow down compared to the center.
- Rotation: This differential speed imparts a rotational motion to the gas. As the gas exits the vent, the rotation causes it to curl back on itself, creating the distinct toroidal shape.
While vortex rings can form at other volcanoes, Etna appears particularly adept at producing them. Scientists theorize that the volcano’s complex internal structure, with multiple vents and conduits, provides ideal circumstances for the necessary conditions to converge.
Photos supplied and courtesy of Maria Liotta