Hawaii Fire Tornado
Firefighters watch a "fire tornado" wreathed with dust and smoke as it swirls on the south slope of Hawaii's Mauna Kea volcano Sunday. The fiery column was spawned during a 1,400-acre (566-hectare) brush fire triggered by regional drought.
Also known as fire whirls, fire devils, or even firenados, these whirlwinds of flame are not really rare, just rarely documented, said Jason Forthofer, a mechanical engineer at the U.S. Forest Services's Missoula Fire Sciences Laboratory in Montana.
For instance, fire tornadoes were recently reported in the state of São Paulo, Brazil, where a three-month long drought has also led to several brush fires.
Forthofer studies fire tornadoes with the aim of protecting firefighters.
"If we can identify conditions that are conducive to fire whirls, that would be a heads-up for firefighters, because there have been some [people] that have been burned by them," he said.
Fire-Tornado Pictures: Why They Form, How to Fight Them
Recent "firenadoes" in Brazil and Hawaii aren't rare, just rarely reported, an expert says: Large-scale versions occur once a year in the U.S.