hazards -conditions favouring intense wildfires

Question 1

what are the 3 elements needed for a wildfire to start?

Answer 1

.heat
.fuel
.oxygen

Question 2

what does heat allow for in the starting of a wildfire?

Answer 2

.allows fire to spread by evaporating moisture in fuels, allowing it to ignite and travel more easily

Question 3

what does fuel give in the starting of a wildfire?

Answer 3

.gives the fire a burneable material allowing the fire to advance

Question 4

what role does oxygen play in the starting of a wildfire?

Answer 4

.oxygen supports the oxidation process, creating heat and gases
.16% is required

Question 5

what are the 3 factors that favour an intense wildfire?

Answer 5

.vegetation type and fuel characteristics
.climate and recent weather changes
.climatic cycles

Question 6

where do wildfires travel faster?

Answer 6

.they travel faster uphill than downhill -so the steeper the slope the faster they travel

Question 7

what does vegetation type and fuel characteristics influence?

Answer 7

.influence the intensity -heat output and the rate of speed -degree of threat

Question 8

how does grassland affect the intensity of a wildfire?

Answer 8

.grassland creates a low heat output

Question 9

how does forested areas affect the intensity of a wildfire?

Answer 9

.forested areas create a high heat output

Question 10

what type of vegetation creates the ideal conditions for a wildfire?

Answer 10

.thick undergrowth with closely spaced trees
.eucalyptus and pine contain lots of oil so burn easily
.eucalyptus shed bark during a fire (firebrands) which encourages the spread
.fine, dry material catches fire easily eg -long grasses or twigs

Question 11

what kind of climate and recent weather conditions are needed to encourage a wildfire to start?

Answer 11

.enough rainfall for vegetation to grow -acts as a fuel
.a distinct dry season -this causes the vegetation to dry up and become more flammable
.strong winds provide oxygen and help the fire spread -they can also trigger lightning storms which are a natural trigger of wildfires

Question 12

how do climatic cycles affect the conditions which favour an intense wildfire?

Answer 12

.El Niño affects global climate and results in a general rise in temperatures, with some regions experiencing wetter weather and some experiencing drier conditions

Question 13

how does El Niño affect global climate?

Answer 13

.during an El Niño year, westerly trade winds weaken so less warm water is transferred westwards which reduces the pressure difference between west and east

Question 14

what results from a pressure difference between west and east?

Answer 14

.a rise in temperature of the eastern Pacific Ocean creating warmer weather in South America -this increases rainfall in South America causing drier conditions in south east Asia and sometimes drought - increasing the risk of wildfires