From thundering pyroclastic flows to scorching rivers of lava, volcanoes are famed for their furious fireworks. They can, however, be just as awe-inspiring during their quieter moments—like when a simmering peak blows a lazy smoke ring into the sky.

Such ephemeral apparitions have been spotted flitting above multiple volcanoes across the world, but it’s been unclear how they are made. Although they can be hundreds of feet across, the rings are short-lived and unpredictable, making them difficult to study. That’s why scientists led by Fabio Pulvirenti, a senior fellow at NASA’s Jet Propulsion Laboratory, decided to do the next best thing and simulate them on a computer.

The team’s virtual volcano, presented at a gathering of the Asia Oceania