Moon and Smoke Rings from Mt. Etna

Explanation: Yes, but can your volcano do this? To the surprise of some, Mt. Etna emits, on occasion, smoke rings. Technically known as vortex rings , the walls of the volcano slightly slow the outside of emitted smoke puffs , causing the inside gas to move faster. A circle of low pressure develops so that the emitted puff of volcanic gas and ash loops around in a ring , a familiar geometric structure that can be surprisingly stable as it rises. Smoke ring s are quite rare and need a coincidence of the right geometry of the vent, the right speed of ejected smoke , and the relative calmness of the outside atmosphere. In the featured image taken about two weeks ago from Gangi , Sicily , Italy , multiple volcanic smoke rings are visible. The scene is shaded by the red light of a dawn Sun , while a crescent Moon is visible in the background.