Blazing bushfires have ravaged parts of Australia, with firefighters battling around 80 fires across Queensland and 50 fires across New South Wales. In total around 400 residents have been evacuated. A total of 630 firefighters have been deployed to tackle the bushfires as they continue to run rampant in the region. But what exactly is a bushfire and how do they start?
What is a bushfire?
A bushfire is a fire that burns in grass, bush or woodland and can threaten life, property and the environment.
It is a combustion or burning of bush, forest or woodland area.
Bushfires are a natural hazard or disaster, common in Australia, but can also occur in many other places around the world where there are large amounts of wood, plant leaves or forest that can burn.
Bushfires may also be called wildfires, brushfires or forest fires.
The extent and ferociousness of a bushfire is determined by the weather, wind speed and humidity, topography and fuel.
How do bushfires start?
Australia’s bushfire season runs from October through March, when it is hottest and driest.
Bushfires are common throughout the year in Australia, but are more likely when the weather is very hot and dry.
The warmer the temperature, the more likely it is a fire will start or continue to thrive.
Bushfires, like all fires, require three ingredients: oxygen, heat, and fuel, which form the “fire triangle”.
Oxygen is a gas which makes up around one fifth of the Earth’s atmosphere, making it very flammable.
In places where oxygen is limited, such as inside logs or in roots growing underground, bushfires can burn slowly for days.
Smouldering fires, where there are fires with smoke but no flame, can suddenly flare up with hot windy conditions.
New bushfires can start because of an influx of new oxygen.
Plants provide the fuel for bushfires with dried grass and leaf litter being most likely to burn.
Green leaves are typically difficult to burn because of the high water content inside them, but in extreme cases they can also be set alight.
Some plants burn more easily than others, eucalyptus trees for instance, burn very easily.
The more fuel there is for a fire, the more likely the fire is to spread which is why fire managers often attempt to reduce the amount of fuel by removing dead plants and conducting controlled fires to burn small amounts of plans to reduce the risk of a large scale bushfire developing later.
To start a bushfire, you also need a point of ignition, which is the heat element of the fire triangle.
This can mainly be achieved in one of two ways: human activity or natural causes.
When human activities causes a bushfire it can be accidental or deliberate.
Whereas natural causes such as lightning can also ignite bushfires.