"Bushfire is an Australian word that is used to refer to any fire burning out of control in bushland areas. In other countries, and increasingly in Australia, the term 'wildfire' is used to describe such events. Bushfires are common in Australia and are associated with the explosive burning of the 'bush', the eucalyptus forests and woodlands. Grassfires are also common."
For a fire to start, the following three things need to be present:
- Fuel (a material that can burn)
- Ignition (heat)
- Oxygen
Fuel:
The greater the fuel load, the hotter and more intense a fire is. The main fuel in bushfires is dry trees, sticks and debris. During droughts or windy, hot, dry conditions, the leaves and small branches of trees can become very dry and flammable (easy to ignite).
Ignition:
The graph below shows the causes of bushfires in Australia. Fires can also be a result of accidents (fore example when a mower blade hits a rock and produces sparks, or power lines are brought down in a strong wind.)
The greater the fuel load, the hotter and more intense a fire is. The main fuel in bushfires is dry trees, sticks and debris. During droughts or windy, hot, dry conditions, the leaves and small branches of trees can become very dry and flammable (easy to ignite).
Ignition:
The graph below shows the causes of bushfires in Australia. Fires can also be a result of accidents (fore example when a mower blade hits a rock and produces sparks, or power lines are brought down in a strong wind.)
Oxygen:
Fires require oxygen, and once lit, a fire will only continue to burn if it has a supply of oxygen. Loose litter on the ground is vulnerable to fire in open spaces because there is plenty of oxygen available for it to burn.
Fires require oxygen, and once lit, a fire will only continue to burn if it has a supply of oxygen. Loose litter on the ground is vulnerable to fire in open spaces because there is plenty of oxygen available for it to burn.
How bushfires attack:
- The fire front: Flames at the front of the fire will ignite anything flammable with which they come into contact. In eucalyptus forests, fires can advance at alarming speeds.
- Embers: Spot fires can break out when hot embers (burning debris such as twigs, leaves, bark) from the fire front are picked up by winds and deposited elsewhere. Embers can be carried as far as 30kms downwind of the fire front.
- Wind: Winds drive a fire by delivering a continuous supply of oxygen. They also blow the flames towards fresh fuel.
Click here to read about some of Australia's worst bushfires:
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Complete the following questions in your work book:
- Define the term 'bushfire'
- What three things must be present for a fire to occur?
- Explain what an ember attack is
- How do winds influence bushfires?
- Have a look at the Department of Fire & Emergency Services (DFES) website and then with a partner, make a "Bushfire Information" poster to inform people of WA of the dangers of bushfires and what safety measures they can take to reduce the risk. Download this DFES "Prepare, Act, Survive" attachment to help as well.
- Complete the interactive activity on page 107 of Pearson
DFES Prepare, Act, Survive | |
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