A Torrent from Hell

Tokyo will probably not forget 1923 in a hurry. The Hifukusho-Ato region of Tokyo was shaken to its foundation by a violent Great Kanto earthquake which ignited a large firestorm and produced a mammoth fire tornado that killed 38,000 people in just 15 minutes.

That deadly statistic clearly casts no doubt on how dangerous fire tornadoes can be. But just what sparks this fearsome beast of nature? What do they look like? Do they disperse? Let’s have a closer look at this natural phenomenon, shall we…

How do they form?
Fire Tornadoes are colloquially known as fire whirls, fire devils and firenadoes. They tend to spawn from wildfires, forming when intense heat and turbulent wind conditions converge to form whirling swirls of air. These swirls can tighten into a tornado-like column.

The core of the column is fire and there is a pocket of spiralling air that feeds oxygen to the core. The temperature inside the core of a fire tornado can reach up to 1,100 degrees Celsius! Fire tornadoes can set ablaze objects in their paths and hurl burning embers hundreds of meters into the air. When the burning embers fall, they can start new spot fires, spreading wildfire.

Fire tornadoes are usually anywhere between 10-30 meters tall, although records show that under the right conditions, large-scale ones have stretched to more than 300 metres in height and 3 metres in width!

These large-scale tornadoes can exceed wind speeds of more than 160 km/h and occur at least once yearly in the US. Most fire tornadoes last only a few minutes but some have been known to persist over an hour. They may vary in colour—from ash and greyish to red and orange (depending on the temperature of the fire and what is on fire).

Fire tornadoes in Singapore
From the above information, I’m sure most of us can safely assume that fire tornadoes are natural phenomenons that only occur in dry, arid places that are prone to bushfires. What are the odds of such a phenomenon occurring in Singapore—one in a million chances? How about one chance in a billion?

Well, truth be told, as a natural phenomenon, it has yet to happen. But did you know it is a daily occurrence as a man-made phenomenon? Here at Science Centre Singapore, there is a towering six metre-tall glass exhibit that houses a flammable liquid at its base. And at precisely 3 pm each day, the liquid is set alight, sucking in the surrounding air through natural convection.

 Air enters the fire via a series of guide vanes at the base of the fire. It flows towards the fire in a spiralling motion, intensifying as it moves towards the core of the flame. The intense spiralling motion stretches into a column of fire—emulating a naturally-occurring fire tornado.

We owe the design of this impressive structure to Dr Her-Mann Tsai, our very own research fellow at the Science Centre who also invented the fire tornado cauldron that housed the Olympic flame at the Singapore 2010 Youth Olympic Games. The prolific innovator has also designed a fire tornado lamp, which is a miniaturised version of the Science Centre exhibit.

Caught out in the wild
Now that you know how impressive but destructive this lean mean towering flame can be, I do not suggest you get mesmerised and stand rooted to the ground in the event you actually encounter a fire tornado in the wild. That would spell dire consequences!

Your best bet for staying alive is to walk the same line Jenny Curran advised Forrest Gump in the 1994 hit movie, Forrest Gump: “Listen, you promise me something, OK? Just if you’re ever in trouble, don’t be brave. You just run, OK? Just run away.”

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