Wildfires Flashcards
Wildfire/bushfire
any rural fire which is uncontrolled and spreading
What do fires need?
Fuel, heat and oxygen
Are wildfires natural
No. Biggest cause is arson. Other causes include lightning, smoking, campfires, debris burning and children.
Heat transfer
Radiation is the transfer of fire to an adjacent object by causing it to combust without touching it. Convection is similar to radiation but in an upward direction. Finally, conduction occurs when flames are in direct contact with another fuel.
What 3 things effect wildfires behaviour
Fuel, topography, weather
Topography
. Slopes - fires move quick uphill than on flatland
. Heat rises
Fuel
. Anything that can burn
. Some fuels are more flammable
. Can be change by us
Weather
. Greatest influence, no control over
. Sun heats up and dries things out
. Moisture - rain, snow, fog
. Wind provides oxygen, carries sparks and dries things quicker
. Wind direction can change fire direction
Ladder fuels
. Fuels that allow the fire to move vertically
. On the ground it is easier to control
. Ladder fuels can move a fire from the ground into the trees
. Fires on the ground are smaller and sparks don’t spread as easily
. Cutting off low branches can stop the fire reaching the canopy
. Properties are safer without ladder fuels
Vegetation
. Most vegetation will burn if exposed to sufficient heat
. Likelihood is often dependent on the plant’s water content
. Following dry climatic conditions, many plants have lower levels of water retained within them and some may be completely dry
. Succulent plants (e.g. Cacti) which store their own water are harder to burn than normal vegetation
. Additionally, certain plant species promote wildfires (e.g. Eucalyptus) as they use the nutrients released from the ash as well as making use of additional light provided by surrounding vegetation being burned to death
. Some pine species have adapted so that their cones only open when there has been a fire, enabling seeds to fall to the ground and germinate in the newly nutrient rich soil below
El Niño
. Climate cycle in the Pacific Ocean with a global impact on weather patterns
. Begins when warm water in the western tropical Pacific Ocean shifts eastward along the equator toward the coast of South America
. Normally, this warm water pools near Indonesia and the Philippines
. This is capable of leading to dry conditions and weather significantly hotter than average
Indian Ocean dipole
. Difference in sea-surface temperatures in opposite parts of the Indian Ocean
. Temperatures in the eastern part of the ocean oscillate between warm and cold compared with the western part, cycling through phases referred to as “positive”, “neutral” and “negative”.
The dipole’s positive phase this year - the strongest for six decades - meant warmer sea temperatures in the western Indian Ocean region, with the opposite in the east
. When an Indian Ocean dipole event occurs, the rainfall tends to move with the warm waters, so you get more rainfall than normal over the East African countries
. In the east of the Indian Ocean, sea surface temperatures will be colder than normal and that place will get a reduced amount of rainfall
Primary impacts: environmental
- Destruction of habitats and ecosystems
- Death and injury of animals, which impacts on food chains and food webs
- Short-term surge of carbon dioxide due to the burning of carbon stores (trees)
- Atmospheric pollution resulting from smoke and water pollution as toxic ash gets washed into water courses
Primary impacts: social
- Loss of life and injury
- Displacement - people being forced to temporarily live elsewhere
- Disruption to power supplies if power lines damaged by strong winds
- Damage to mobile phone stations and telephone exchanges affecting communications
Primary impacts: economic
- Damage/destruction of structures (homes, public buildings such as schools, fences and field boundaries)
- Financial loss (loss of earnings, damage costs)
- Destruction of businesses
- Loss of crops and livestock
