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Bush firefighter > Bush fire behavior > Flashcards

Bush fire behavior Flashcards

1
Q

Fuel varies in its —-, —-, —-, —-, and —-

A

Type, Amount, size, Moister content and Arrangement

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2
Q

what are Fires affected mainly by?

A

Fuel, weather, and typography.

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3
Q

what are the types of fuel?

A

Grass

Leaf litter: also known as surface litter

Humus/duff: decomposing/decomposed leaf litter

Small herbs/shrubs: called near-surface litter

Shrubs: heathlands and understory layer in forests. The things below the trees.

Trees:

Fine fuels

Heavy fuels: also known as course fuels

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4
Q

Does grass burn slowly or fast? what determines the risk of grass fires?

A

burns rapidly. dryness determines the level of danger and risk of fire starting.

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5
Q

How do trees burn?

A

dense forests usually burn slower than grass but more intensely

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6
Q

Why is Eucalyptus bark dangerous?

A

Eucalyptus bark often causes spotting.

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7
Q

What are the differences between Fine fuels and heavy fuels?

A

Fine fuels are less than 6mm, (like twigs, grass and leaves). It burns easily and quickly, often causing spotting and more fires due to ember attacks.

Heavy fuels are more than 6mm (things like sticks and logs). it Burns slower due to its size, and it’s less easily ignited.

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8
Q

Fire is mainly spread by which fuel?

A

fine fuels. usually, the more fine fuels, the faster the rate of spread.

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9
Q

What most often causes heavy fuels to ignite?

A

heavy fuels to burn as the fire front spreads over the top of it

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10
Q

which bruns faster? Sparsely placed fuel or closely placed fuel?

A

Fuel that is grouped together (fine fuel especially) burns faster than sparse fuel.

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11
Q

Loosely pilled —- burns quickly and intensely.

A

fine fuel

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12
Q

A ladder of fuel leading upwards leads to what?

A

the fire spreading upwards (crown fire)

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13
Q

Which is better for fires, high or low moisture content?

A

Dry stuff burns more easily and faster than wet stuff

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14
Q

What makes fuel moisture content vary?

A

Weather conditions, whether the plant is living or dead, the type of plant, and dryness of the soil. Heavy fuel takes longer to dry out.

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15
Q

Dead fuel ether gives of or takes up moister based on which factors?

A

daily humidity (fine fuels change quickly, heavy fuels rarely change much), time since last rainfall (fine fuels change quicker than heavy fuels), dryness of soil (wet soil makes things wet, dry soil makes things dry)

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16
Q

How do you Measure moisture content?

A

fuel moisture content can be estimated based on weather conditions and current dryness. The most common method is a device called the Wiltronics ME2000 fine fuel moisture meter. Grass and croplands can be measured by appearance.

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17
Q

What are the key parts of weather?

A

Temperature:

Wind speed

Relative Humidity

Atmospheric stability

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18
Q

why does temperature matter in firefighting?

A

heat=dry fuel=easier ignition

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19
Q

what are the factors that make wind matter in firefighting

A

Wind increases the speed and fierceness of fire by giving it oxygen, bending the fire closer to the ground ahead of itself, causing it to ignite more easily due to radiation, bending the convection column over fuel and drying it out, causing spot fires due to wind carrying off light materials that have caught on fire. Changes in wind direction can be very dangerous for afire, especially if they happen quickly and without prior knowledge.

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20
Q

what is Relative Humidity?

A

how much water that is in the air

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21
Q

why does Relative Humidity matter in fire fighting?

A

Fine fuel moisture levels vary depending on humidity. dry fuel bad

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22
Q

What is the daily humidity cycle?

A

as heat rises across the day, humidity drops; as the night comes and temperatures fall, humidity rises.

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23
Q

Atmospheric stability=?

A

Atmospheric stability is the vertical movement of air patterns. Hot air rises, and cold air replaces it.

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24
Q

Stable Atmospheric conditions: are characterised by what?

A

Stratus clouds (layered type), smoke columns that drift apart after rising a limited amount, layers of fog, light and easily predictable winds.

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25
Q

are Stable Atmospheric conditions good or bad for fire fighters

A

good. Fires are predictable in this circumstance.

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26
Q

Unstable atmospheric conditions are characterised by what?

A

cumulus clouds (cottonwool type) with notable upward growth, smoke collins that rise to great heights, gusty and unpredictable winds, strong winds that may come from thunderstorms or rain clouds, whirlwinds can occur, and sometimes blue sky.

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27
Q

Down bursts=?

A

gusts of strong air that travels downward and then outward.

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28
Q

what are the two types of downbursts?

A

They can be dry downbursts (caused by normal clouds) or wet downbursts (caused by thunderstorms).

29
Q

how long do downbursts last?

A

They tend to last from 10-30 mins

30
Q

what signals a dry downburst?

A

Dry downbursts can only be signalled by virga (rain that doesn’t reach the ground)

31
Q

How do people measure atmospheric stability?

A

it is ranked on the conscious Haines index or cHaines index for short

32
Q

How do Slopes affect fire, and why?

A

due to radiant heat preheating to fuel in front of the fire when travelling up hill, fires will burn faster when travelling up a slope

33
Q

For every —-degrees of upslope, double the rate of spread.

A

10

34
Q

What is an Aspect?

A

it Is the direction that a slope or feature faces

35
Q

How do Aspects affect fire, and why?

A

Due to the sun’s radiation, aspects on the north and west faces will be dryer and more easily ignited.

36
Q

Aspects on the — and —faces will be dryer and more easily ignited. —- and —-facing aspects will become dangerous and unpredictable in droughts

A

Aspects on the north and west faces will be dryer and more easily ignited. Aspects on the south and east faces will be dryer and more easily ignited

37
Q

how do Topography and wind interact?

A

it can behave complexly. Often, exposed faces have increased wind while their other side is calm, though not always; sometimes, the wind can move in the opposite direction on the lee side.

38
Q

what is Vortricty-driven lateral spread (VLS)?

A

It causes the fire on the lee side of the incline to behave erratically, moving in directions not in line with the prevailing wind direction. It can move at a right angle and cause spotting on the lee side

39
Q

VLS usually occurs when a wind speed higher than —- meets an incline above —.

A

usually occurs when a wind speed higher than 25km meets an incline above 25.

40
Q

How does Elevation affect a fire?

A

It can influence weather and vegetation. The temperature drops as you increase in elevation; however, the temperature decrease is mainly cancelled out by the decrease in humidity and exposure to the sun. Fires behave differently at higher elevations; thus, fires that span many elevation levels are difficult to fight.

41
Q

what are the three types of bushfires learnt in this chapter?

A

Surface fires:

Ground fire

Crown fires

42
Q

What is a surface fire?

A

Surface fires are fires that burn along the ground and do not burn the crowns of trees. They are a very common type of fire and burn fuel, such as grass and shrubs.

43
Q

what is a ground fire?

A

Ground fires burn material in the soil, such as peat and low-ground material, like leaf litter. They don’t produce a lot of smoke and often go unnoticed later, causing surface fires. They occur in a few parts of Australia.

44
Q

what is a crown fire?

A

Crown fires burn on the tops of trees, often ahead of intense surface fires. They are the most dangerous type of fire due to increased movement speed caused by higher wind, and falling branches that can start surface fires. They are often accompanied by short or long-distance spotting (two and a half km is not uncommon)

45
Q

what are the 7 Fire ground safety rules learnt in this chapter?

A

Maintain situational awareness: look for hazards; what’s happening now? What could happen?

. Use safety techniques that match the situation: start from a safe anchor point, always have an escape route, and stay out of dead man’s zone.

. Safety refuges must be available: single refuges must be within 100m of each other, and multiple in each direction can be up to 250m away. They must be 4 times as deep as the likely flame height.

. Escape roasts may include rivers, trails, prepared roasts ect.
. Keep at least 30m away from bulldozers or other vehicles unless being signaled by the driver.

. Only travel in trucks or tankers. Grassfires can be fought from crew operational ares. Use seatbelts

. Beware of vehicle and equipment hazards

. Know and practice survival techniques

46
Q

What are support operations, and what do they involved?

A

they are Operations that are done by non-active firefighters or brigades near the incident.
Catering: food, water
Logistics: transport, extra equipment etc
Communications: calling out brigade members to the fire, meetings, correspondence etc
First aid
Maintaining brigade facilities and equipment

47
Q

what are the 3 ways bush fires can involve buildings?

A

Radiation: The building may ignite due to radiant temperatures from a nearby fire

Direct flame content: buildings may ignite due to direct contact with nearby burning materials

Ember attack: are the most common and dangerous method if bullying ignition. The can enter through windows or air vents and ignite flammable materials inside; they can also be caught on corners, fences or any other fixtures around the house.

48
Q

What is the rear/heel of the bush fire? How does it behave?

A

This is the opposite of the head of the fire. It has the slowest spread and lowest flame height.

49
Q

What is the point of origin? How should you interact with it?

A

Point of origin: Where the fire started. it should be left alone for investigators to examine later.

50
Q

what is the Flank/side?

A

Flank/side: This is less intense than the head of the fire. From the back, it can be described as the left or right flank.

51
Q

What are the Fingers? why do they happen?

A

Fingers: strips of fire that have advanced beyond the head of the fire due to varying winds

52
Q

what is the Head of the fire?

A

the Head of the fire: also called the fire front. This point has the fastest spread and most intense heat and flame height, and it is affected by wind, topography, and fuel.

53
Q

what are Spot fires?

A

Spot fires: small fires started by embers

54
Q

what are the Factors in spotting?

A

Atmospheric instability affects the convection column, which affects the severity of the spread. Fuel also affects how far the embers will travel. Eqaliptus stringy bark = intense short spotting (2km), and candle bark = long-distance spotting.
Atmospheric instability affects the convection column, which affects the severity of the spread. Fuel also affects how far the embers will travel. Eqaliptus stringy bark = intense short spotting (2km), and candle bark = long-distance spotting.

55
Q

what are the Dangers of spotting?

A

they can cause the main fire to exhilarate in spread and speed, and it can be dangerous for firefighters due to inclosing them and cutting off escape routes. If mutiny spot fires start around you, you must evacuate immediately unless you are certain that your crew has enough resources and a large safe zone.

56
Q

Species in the sclerophyll forest=?

A

mostly eucalypt trees.

57
Q

Fuel in sclerophyll forest=?

A

mainly leaf litter (fine fuel). Eucalypt leaves are highly flammable if enough of them accumulate, fires can spread upwards and cause a crown fire.

58
Q

How do Fires on a moderate fire day in sclerophyll forests often behave?

A

a typical dry sclerophyll forest fire with moderate fuel under low to moderate fire danger conditions will have flame hights of about 2m - 3m and will be unlikely to spot. It will travel at about 100 meters per hour.

59
Q

How do Fires on a high fire day in sclerophyll forests often behave?

A

In high-fire danger situations, the same fire may have flame heights of 7m-8m, travel a km per hour, and spot up to 2km ahead.

60
Q

How do Fires on an extreme fire day in sclerophyll forests often behave?

A

Under extreme conditions, the fire would crown it would move at couple km an hour and spot 6km head.

61
Q

Scrub in sclerophyll forest=?

A

Fires that involve scrub are far more unpredictable and travel far faster, even under the same conditions.

62
Q

heath fire=?

A

Fires can behave wildly due to the inconsistent spacing. Some areas have little fuel while others teem with it with only a small space between them.

63
Q

Open scrub fires=?

A

Sometimes, the scrub will be too far apart to support a fire, but if conditions (mainly wind) are intense enough it can occur.

64
Q

what are the Fire characteristics of a pine plantation?

A

it changes as the pine trees grow. Young trees will be surrounded by grass and just be grass-fired. From the ages of 3 to 6, even smaller fires will crown easily, and from the ages of 7 to 10, the canopy will fill in, and the grass on the floor will die and be replaced with pine needles; these are at their most combustible when they turn red.

65
Q

How do Older pine forest fires behave?

A

from 11-20 pine trees may be harvested, and the grass can reappear. Pine slash may be left around. Fires in pine needle duff may smoulder and spread through root systems.

66
Q

Fire in extreme conditions=?

A

The traits of extreme fires are extensive spotting, thick smoke that impacts visibility, and sudden flare-ups due to hills or new fuel.

67
Q

Safeguarding the community=?

A

You may stop fighting the fire and instead focus on moving people to more defendable locations and keeping them safe rather than stopping the spread.

68
Q

Firefighting in extreme conditions=?

A

can be dangerous and difficult. Communications often get overloaded, and people and people can be excited or afraid.

69
Q
A

Bush firefighter (4 decks)

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