Hazards BK 6 - Fires in Nature Flashcards
when do fires occur
when oxygen combines with carbon, hydrogen and other organic material, producing flame, heat and light
what percentage of fires actually accounts for the 95% of areas burnt
3%
what are crown fires
fires that pass from one tree to another
what’s a surface fire
where a wall of fire along what’s called either a combustion front or flaming combustion
what’s a ground fire
one that moves slowly at ground level through what can be known as glowing combustion
how hot can ground temperatures get during surface fires
over 1000 degrees
what four things can impact the nature of the fire
plants involved
strength of winds
topography of the area
behaviour of the fire
what’s a retardant
chemicals sprayed on to fires in order to slow them down
define pyrophytic vegetation
phrophytes are plants adapted to tolerate fire, such as having thick bark etc
what temperatures do forest fires burn at
between 540 and 1100 degrees
what’s pyrolysis
a chemical reaction causing organic material to decompose as a result of high temperatures
what does flaming combustion do
burn wood and organic matter which releases energy
how can fire be used as a positive for regeneration
farmers and national park rangers around the world have used controlled burning for years and the minerals that are released from the burning of vegetation are beneficial to the soil
what’s a type of species that can withstand fire
baobab tree, because their bark tissue and high moisture content
what’s the three stages of a fire
preheating
flaming combustion
glowing combustion
what happens during preheating
temperature begins to rise, gases begin to be released and wood breaks down by the process of pyrolysis
what happens during flaming combustion
fast burning of wood, cracks develop in wood and releases more gases
energy is released by convection and radiation
what happens during glowing combustion
wood burns more slowly and at lower temperature, the fire consumes itself instead of the gases released by pyrolysis
what are the two biggest causes of wildfires
an ignition source
fuel
what are some examples of ignition sources of wildfires
lightning
climate change
arson
controlled burning
disposable bbq
lava flows
are fires usually caused by more natural or human causes
himan
what’s the main sauce of fuel for a wildfire
plants or vegetation
what’s 5 factors that will affect whether wildfires will start
presence of vegetation
climate
recent weather
wind
topography
what percentage of fires are triggered by people
80-90%
where do wildfires tend to happen
in rural areas usually but now because of humans they are occurring more in urban areas
what two things makes an area most likely to be affected by wildfires
dry vegetation and lightning strikes
what 3 semi arid locations are likely to have a wildfire
parts of austria lie
USA and canada
southern europe like france and italy etc
are wild fires seasonal or yearly
usually seasonal
what side of the equator do wildfires tend to occur on
south, such as south mercian and africa etc
what are species called that can withstand fire
pyrophytic
have wildfires impacted tropical rainforests yet
no, due to the humid climate but recent burning for forest clearing have got out of hand
what’s a specific area that wildfires have increasingly been a threat too
LA, California
what’s three reasons LA suffered many wildfires
-much of the area is covered by drought resistant chaparral, as the area is too dry for much tree growth
-a dry wind called santa ana that descends from local mountains increases dryness
-consists of low density buildings where vegetation is exposed to fire risk
what’s 3 social impacts of wildfires
-people may become trapped and killed
-communities may be split up if people move away following a fire
-visibility will be reduced by smoke and can cause accidents
what’s 3 economic impacts of wildfires
-wildfires are very expensive for emergency services to tackle
-infrastructure can be damaged and needs to be replaced
-timber can be burned the industry provides jobs and income
what’s 3 environmental impacts of wildfires
- some fires may benefit the ecosystem by clearing vegetation
-the structure of soil can be altered even it is exposed to high temperatures
-larger species of wildfire may be driven from an area by fire
what’s two responses to wildfires in terms of preparedness
-education, governments tend to provide guidance for people for explain warning systems and evacuation routes etc
-computer modelling, to understand and predict fire behaviour, studying ways to prepare for fires etc
what’s a response to fires in the short term
-sending out humanitarian aid, search and rescue teams, emergency services etc
what’s an example of a response to fires in terms of mitigation
The colarado state forest service, encourage the creation of fire adapted communities, providing home wonders and communities with advice on how to reduce property damage by fire
what’s an example of adaptation in response to a wildfire
Montecito, residents have to adapt by having a 35 meter space around their home built out of ember and fire resistant materials
