Scientists Say: Blue whirl

Under the right conditions, these rare blue-flame phenomena swirl into existence

When floating fuel ignites, a pool fire forms (left). Sometimes, a pool fire rises into a tall yellow column called a fire whirl (center). And sometimes, that fire whirl stabilizes into a smaller — but much hotter — blue whirl (right).

H. Xio, M.J. Gollner, E.S. Oran/PNAS 2016

By Katie Grace Carpenter

November 24, 2025 at 6:30 am

Blue whirl (noun, “BLOO WURL”)

A blue whirl is a kind of flame that most often occurs when fuel burns while floating on the surface of water.

There are many different types of flames. They arise from different types of combustion — a chemical reaction that releases heat. A fresh campfire may blaze yellow, giving off lots of smoke and soot. A gas stove might burn blue, smokeless and super-duper hot. And floating fuel can ignite calmly spinning blue whirls.

Scientists discovered blue whirls by accident in 2016. They had been studying another kind of flame called a fire whirl. These flames look like swirling yellow tornadoes.

The team set up conditions to make fire whirls in the lab by burning fuel floating on water. This first creates what is called a pool fire. That’s when the floating fuel vaporizes first, and then that vapor burns. A pool fire often changes into a yellow fire column called a fire whirl.

But to the researchers’ surprise, some fire whirls suddenly changed. Chaotic, yellow fire tornadoes swirled into calm blue flames. In 2020, scientists mapped the structure of blue whirls. Four smaller flames come together to create this storm of fire perfection.

Blue whirls can form in liquid fuel floating on water. The fire shifts from a tornado to a steady blue flame, which is made up of four different types of flames.

Fire whirls can occur outside the lab. For example, when wind interacts with the fire just right — or just wrong — it can create a vortex of flame. When these occur in house or forest fires, they can threaten lives. Upward winds from the vortex can toss burning debris into the air. That can spread a fire.

Blue whirls burn without these wild wind patterns. That makes blue whirls more predictable than normal fire whirls. Blue whirls also burn “cleaner” than typical fire whirls. That is, they produce very little smoke and soot.

Scientists hope blue whirls may one day help clean up oil spills in the ocean. And because blue whirls burn cleaner and more predictably than most fire, they could also be used to build more efficient, cleaner-burning engines.