Extraterrestrial visitors? Airborne jellyfish? Neither or both? What are the nebulous, ringed wraiths drifting above the world’s most active stratovolcano?
Rest easy, SETI: The ethereal structures that one Bronte, Sicily woman photographed from her home on April 5 are the simply closest thing to smoke rings that a volcano can make.
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Rising above Mount Etna’s volatile, 3,357m summit, the rings are actually clouds produced by venting gases. “Volcanic smoke rings” have appeared elsewhere, but it’s clearer now how they’re formed.
In fact, the rings aren’t “smoke” at all. During active periods, volcano calderas release gases like carbon dioxide and sulfur dioxide in short spurts. The hot gas surges upward through the atmosphere, and when it reacts with airborne vapor, it can create a cloud. The mechanism is similar to the one that forms plane contrails — only here, the staccato discharge makes ring-shaped cloud puffs.
It’s not unusual to see a single volcanic smoke ring at once. But lately, Mt. Etna has thrown up multiple rings on several occasions. The July 2023 eruption also produced several rings at once, and the phenomemon also occurred about a decade earlier. German volcanologist Tom Pfeiffer photographed the 2023 smoke rings for Hidden NY.
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“Being Etna, she exaggerates: not only one ring every now and then, but she made dozens if not hundreds during a few hours, often in a row,” he explained.
