Fire tornado: A rare phenomenon

Dramatic thunderstorms, lightning, and hailstorms create havoc, but have you ever thought what a fire tornado can do? It is a rare occurrence but some parts of the world, like the Californian Forest fires, have experienced it where major fire outbreaks have taken place. Fire tornadoes can be a common sight in areas where there are active volcanoes. Smaller-scale fire whirls can appear in bonfires. In some parts of the world, it is known as firenado while in others, like Australia they are called pyrotornado. Historically, firenadoes have caused massive destruction to property, wildlife, and human life. Here’s all your kids need to know about these scary fire whirls. 

What are fire tornadoes? 
Fire tornadoes, also called fire whirls, are rare atmospheric tornado events. They are a whirlwind induced by fire and often composed of smoke or ash. A tornado like this starts with a strong warm wind made visible by smoke, with intense rising heat and turbulent wind conditions to form whirling eddies of air. When such winds are strong, they can contract a tornado like a vortex tube formation that sucks in debris and combustible gases creating fire. Fire tornadoes are not like classic tornadoes because their vorticity or the spinning capacity is derived from the temperature, lifting surface winds instead of the rapid air mass found within a regular tornado. 

How are they formed? 
A fire tornado usually consists of a burning core and a rotating pocket of air. This type of tornado is usually generated when a wildfire or firestorm creates wind that turns into a spinning flame vortex. Most fire tornadoes are fuelled by carbon-rich gases released by burning vegetation on the ground level. These gases then get sucked up by the air reaching the core where there is enough heated oxygen to ignite it.  

Fire tornadoes can reach up to 1,090 degree Celsius. These are usually 10-50 m tall and a few meters wide. Depending upon the intensity, a fire tornado can last for a few minutes or can go up to an hour if the speed is high and it goes up by more than 1km. Fire tornadoes have the power to uproot big trees, burn a person alive if he comes in contact, and can cause multiple fires as they spread quickly. Topography and wind conditions determine the strength and formation of a fire tornado. 

Classification of fire tornadoes 
These rare and violent natural occurrences have the ability to spread across a massive forest causing havoc. Fire tornadoes are classified into three categories: 

• Type 1: Over the burning area it can be stable and centered. 
• Type 2: It can be stable and transient around the downwind burning area. 
• Type 3: Windy and steady, centered over an area adjacent to the burning area. 

Blue whirl 
Recently, scientists have found a new kind of tornado, known as the ‘blue whirl’. It is thought to be a bubble mode of the vortex breakdown formed over a water surface that provides a smooth boundary. The most fascinating idea of the blue whirl is the yellow flame indicating soot-free combustion. The fast-mixing capacity of fuels favours the soot-free sight like the jet diffusion flames.