Fires in nature Flashcards
What are wildfires, what are the types and how do they behave?
There are three types of fire:
- Ground fire
- Surface fire
- Canopy fire
Heat transfer process heats the vegetation ahead of the flames which can cause rapid spread of the fire, this can also be done by ignitors which are blown from the main fire to further ahead.
Conduction also occurs which is when the heat from the main fire causes vegetation nearby to combust.
Ladder affect occurs as the fire moves upwards from ground to canopy.
Natural and human causes of wildfires?
Majority of wildfires which threaten lives are result of human actions such as discarded cigarettes and poorly controlled campfires, broken power lines etc.
Naturally started by lightning strikes.
Environmental impacts of wildfires?
- Destruction of habitats/eco-systems
- Short term serge of CO2 due to combustion.
- Increased carbon emissions = EGE
- Lack of vegetation increases flood risk.
Social impacts of wildfires?
- Loss of life and injury
- Displacement of people as forced to evacuate
- New employment streams needed
- New rules and regulations put in place
Economic impacts of wildfires?
- Damage to structures
- Financial loss through loss of income and damage costs
- Cost of rebuilding or relocation
- Cost of future preparedness.
Political impacts of wildfires?
- Pressure on local authorities an emergency services
- Develop strategies for preparedness/mitigation.
What conditions favour wildfires?
Vegetation type:
- Forest fires more intense than grassland fires.
- Moisture content also has huge impact, favour dry conditions.
- Nature of fuel also important- trees/plants high in oil are volatile.
Climate/ weather conditions:
- Heatwaves and drought conditions create favourable conditions and most occur after or during prolonged dry periods.
- Strong dry winds also needed.
How do wildfires impact global systems?
- Local eco-systems affected, habitats destroyed and animals killed
- Toxic ash washed into water cycle
- Loss of vegetation affects water cycle less precipitation and more run off.
- Burning releases CO2 increases climate change and reduces carbon stores.
Risk management of wildfires through preparedness ?
- Early detection of hazards and the suppression of wildfires is important.
- In USA weather service issues warnings to fire stations and residents when critical conditions occur.
- Red flag warning issued when conditions for extreme fire behaviour may be met in 24hrs.
- Fire breaks around homes remove all vegetation so that nothing can be ignited.
- Clear evacuation routes and practices so people know exactly what to do.
Risk management of wildfires through mitigation?
- Early fire detection can be done through satellites and infra-red sensors.
- NASA developing drones for surveying vast areas of land - Can often be controlled through back burning which is when they burn ahead of the fire so it cannot relight.
- Disaster/fire aid and insurance can help mitigate the impacts.
Risk management of wildfires through prevention?
- Controlled burning reduces the amount of fuel available.
- Public awareness needed such as ‘fire bans’ during fire season.
- Smokey bear in USA 96% recognise and 70% know message.
Risk management of wild fires through adaptation?
- Involves learning to live with the hazard
- Burn away old diseased wood to enable free moist growth.
- Planning regulations to reduce access to high risk areas as well as specifications on building materials used.
When was the Paradise fire?
- Began 8th of November 2018.
- Embers flew 2.5 miles ahead of fire front
- Temperatures over 1150 degrees.
Causes of the paradise wildfire?
- Electricity company thought to be blamed for not keeping up with the maintenance of their electricity pylons.
What conditions favoured the Paradise wildfire?
- Drought conditions for 7 months prior.
- Low humidity with hot gusting dry winds (25-35mph)
