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Questions and Answers
Topography can directly and indirectly affect fuels and their availability for combustion.
Topography can directly and indirectly affect fuels and their availability for combustion.
True (A)
Of the three primary environmental factors that influence fire behavior, which is the least variable?
Of the three primary environmental factors that influence fire behavior, which is the least variable?
Topography
The least critical form of heat transfer that influences the rate of spread in a running wild land fire is:
The least critical form of heat transfer that influences the rate of spread in a running wild land fire is:
Conduction
The point to which a combustible material must be heated to produce self-sustaining combustion is known as the:
The point to which a combustible material must be heated to produce self-sustaining combustion is known as the:
Fireline intensity is dependent upon:
Fireline intensity is dependent upon:
Two requirements for long range spotting are wind and a well developed convection column.
Two requirements for long range spotting are wind and a well developed convection column.
A fire that advances through canopies of brush and trees is known as a:
A fire that advances through canopies of brush and trees is known as a:
Fire is burning in litter on top of the ground, but occasionally carries into the crowns of individual trees, which produces burning embers that start new fires outside the fire perimeter.
Fire is burning in litter on top of the ground, but occasionally carries into the crowns of individual trees, which produces burning embers that start new fires outside the fire perimeter.
What happens when a fire begins burning into the crowns and spreads through the canopy?
What happens when a fire begins burning into the crowns and spreads through the canopy?
Upward moving air contracts and warms.
Upward moving air contracts and warms.
As air sinks, it:
As air sinks, it:
Why do dry climates usually have lower nighttime temperatures than humid climates?
Why do dry climates usually have lower nighttime temperatures than humid climates?
On average the RH doubles with each 20F decrease of temperature, or halves with each 20F increase in temperature.
On average the RH doubles with each 20F decrease of temperature, or halves with each 20F increase in temperature.
The lowest RH occurs with the highest temperature.
The lowest RH occurs with the highest temperature.
RH is usually lower on north aspects.
RH is usually lower on north aspects.
Cloudiness has little effect on relative humidity and temperature.
Cloudiness has little effect on relative humidity and temperature.
The type of vegetation has little effect on temperature and humidity.
The type of vegetation has little effect on temperature and humidity.
RH measures the amount of moisture in the air.
RH measures the amount of moisture in the air.
Clouds form in layers.
Clouds form in layers.
Gusty winds are categorized as:
Gusty winds are categorized as:
Smoke column spreads out after limited rise.
Smoke column spreads out after limited rise.
Clouds grow vertically.
Clouds grow vertically.
Firebrands are lifted into the convection column.
Firebrands are lifted into the convection column.
Temperature decreases with an increase in elevation when an inversion is present.
Temperature decreases with an increase in elevation when an inversion is present.
What is the general effect of stable air on wild land fires?
What is the general effect of stable air on wild land fires?
What conditions will occur under a surface inversion during the morning hours?
What conditions will occur under a surface inversion during the morning hours?
What are the different lighting processes that can lead to thunderstorm development?
What are the different lighting processes that can lead to thunderstorm development?
Unstable air can often be found in low pressure systems and on the leading edge of cold fronts.
Unstable air can often be found in low pressure systems and on the leading edge of cold fronts.
Unstable air can be formed by either heating the air near the ground or by cooling the air aloft.
Unstable air can be formed by either heating the air near the ground or by cooling the air aloft.
Wind direction is:
Wind direction is:
A wind is caused by:
A wind is caused by:
A slope wind is caused by:
A slope wind is caused by:
Foehn winds can adversely affect wild land fires because they can produce:
Foehn winds can adversely affect wild land fires because they can produce:
When stable air is forced over a mountain range, and then descends the leeward slopes as dry, warmed air, it is called:
When stable air is forced over a mountain range, and then descends the leeward slopes as dry, warmed air, it is called:
Bends in canyons are likely places for wind eddies to form.
Bends in canyons are likely places for wind eddies to form.
Local winds are best defined as:
Local winds are best defined as:
East, Mono, Santa Ana, and Chinook are all examples of:
East, Mono, Santa Ana, and Chinook are all examples of:
Air flows clockwise around low pressure systems and counterclockwise around high pressure systems.
Air flows clockwise around low pressure systems and counterclockwise around high pressure systems.
Slope affects fuel availability to burn because:
Slope affects fuel availability to burn because:
Select the correct statement regarding the shape of the country and its effect on wild land fire behavior.
Select the correct statement regarding the shape of the country and its effect on wild land fire behavior.
Aspect affects fuels and their availability to burn because:
Aspect affects fuels and their availability to burn because:
Select the statement that best describes the effect of slope steepness on fuel availability.
Select the statement that best describes the effect of slope steepness on fuel availability.
A fuel model is defined as:
A fuel model is defined as:
The 4 fuel groups as defined in the Fire Behavior Prediction System are:
The 4 fuel groups as defined in the Fire Behavior Prediction System are:
Available fuels are:
Available fuels are:
Fuel loading definition:
Fuel loading definition:
Fuel moisture content definition:
Fuel moisture content definition:
Fuel size and shape definition:
Fuel size and shape definition:
Fuel chemical content definition:
Fuel chemical content definition:
Which of the following fuel characteristics affect all 6 wild land fire behavior concerns; i.e. ignition, spread, intensity, spotting, torching, and crowning?
Which of the following fuel characteristics affect all 6 wild land fire behavior concerns; i.e. ignition, spread, intensity, spotting, torching, and crowning?
Which fuel has a higher surface-area-to-volume ratio?
Which fuel has a higher surface-area-to-volume ratio?
The 1 hour timelag fuel category is:
The 1 hour timelag fuel category is:
Fuel moisture timelag can best be described as:
Fuel moisture timelag can best be described as:
1 hour timelag fuel moisture is used in fire behavior calculations to determine:
1 hour timelag fuel moisture is used in fire behavior calculations to determine:
The five stages of vegetative development for live fuel moisture are:
The five stages of vegetative development for live fuel moisture are:
The following statement best describes timelag fuel categories:
The following statement best describes timelag fuel categories:
Foehn winds always cause fuels to gain in moisture content.
Foehn winds always cause fuels to gain in moisture content.
Dead grass reacts like a 1 hour timelag fuel.
Dead grass reacts like a 1 hour timelag fuel.
The fuel moisture at which fire will not spread is the:
The fuel moisture at which fire will not spread is the:
Inputs used to determine fine dead fuel moisture content are:
Inputs used to determine fine dead fuel moisture content are:
Select the fuel complex that would reach its moisture of extinction first during nighttime humidity recovery.
Select the fuel complex that would reach its moisture of extinction first during nighttime humidity recovery.
If the wet bulb is not read at its lowest point, what will happen?
If the wet bulb is not read at its lowest point, what will happen?
What weather processes can and should be monitored visually?
What weather processes can and should be monitored visually?
When a cold front or thunderstorms are forecast in the vicinity of a fire, what is the most important information a security weather watch can provide?
When a cold front or thunderstorms are forecast in the vicinity of a fire, what is the most important information a security weather watch can provide?
The criteria for determining a Red Flag Warning is a combination of high to extreme fire danger and a critical fire weather pattern such as:
The criteria for determining a Red Flag Warning is a combination of high to extreme fire danger and a critical fire weather pattern such as:
Spot weather forecasts are:
Spot weather forecasts are:
Initiate action based on ____ fire behavior.
Initiate action based on ____ fire behavior.
Fire which can generally be attacked at the head or flanks by persons using hand tools have flame lengths that are:
Fire which can generally be attacked at the head or flanks by persons using hand tools have flame lengths that are:
Effective windspeed is the mid-flame windspeed increased for the effect of slope on fire spread.
Effective windspeed is the mid-flame windspeed increased for the effect of slope on fire spread.
The surface fire characteristics chart relates:
The surface fire characteristics chart relates:
Regardless of fine dead fuel moisture percentage, rate of spread is determined by the live fuel moisture.
Regardless of fine dead fuel moisture percentage, rate of spread is determined by the live fuel moisture.
En route to a fire you notice that smoke from a burning haystack rises straight up. What could this indicate on a wild land fire?
En route to a fire you notice that smoke from a burning haystack rises straight up. What could this indicate on a wild land fire?
A ground fire has burned under a thick stand of pine reproduction. What potential problems could occur?
A ground fire has burned under a thick stand of pine reproduction. What potential problems could occur?
You are on a fire in the coast range of Southern California. The fire is burning above you on the slope. At 1800, you experience a sudden calm in the sea breeze. What might you expect to occur next?
You are on a fire in the coast range of Southern California. The fire is burning above you on the slope. At 1800, you experience a sudden calm in the sea breeze. What might you expect to occur next?
The convection column from your fire has developed to several thousand feet as a result of intense burning. You notice the top of the column has been sheared off. What could happen next?
The convection column from your fire has developed to several thousand feet as a result of intense burning. You notice the top of the column has been sheared off. What could happen next?
Wild land fire behavior in the third dimension:
Wild land fire behavior in the third dimension:
4 factors that are responsible for the occurrence of fire behavior in the third dimension are:
4 factors that are responsible for the occurrence of fire behavior in the third dimension are:
Three stages of crown fire development are:
Three stages of crown fire development are:
Crown fire development depends on crown flammability along with adequate surface-to-crown and crown-to-crown heat transfer.
Crown fire development depends on crown flammability along with adequate surface-to-crown and crown-to-crown heat transfer.
The factors that contribute to the spotting problem can be classified into three general areas:
The factors that contribute to the spotting problem can be classified into three general areas:
Probability of ignition is determined by:
Probability of ignition is determined by:
Vortices are grouped as vertical or horizontal depending on their axis of rotation.
Vortices are grouped as vertical or horizontal depending on their axis of rotation.
When the wild land fire environment is dominated by a ______ fire, the convection column overpowers the wind field.
When the wild land fire environment is dominated by a ______ fire, the convection column overpowers the wind field.
Continuous fine fuels, heavy fuel loadings, ladder fuels, crown spacing, and special fuel situations are fuel characteristics that should NOT be monitored.
Continuous fine fuels, heavy fuel loadings, ladder fuels, crown spacing, and special fuel situations are fuel characteristics that should NOT be monitored.
Low RH and a high 1000 hour timelag fuel moisture are both critical fuel moisture indicators that should be monitored.
Low RH and a high 1000 hour timelag fuel moisture are both critical fuel moisture indicators that should be monitored.
Steep slopes, chutes, saddles, and narrow canyons are terrain indicators that should be monitored.
Steep slopes, chutes, saddles, and narrow canyons are terrain indicators that should be monitored.
Strong surface winds, lenticular clouds, high fast moving clouds, approaching cold front, cumulonimbus development, and sudden calm or battling winds are all indicators of wind that are not of great concern to wild land firefighters.
Strong surface winds, lenticular clouds, high fast moving clouds, approaching cold front, cumulonimbus development, and sudden calm or battling winds are all indicators of wind that are not of great concern to wild land firefighters.
Which of the following is an indicator of stable air?
Which of the following is an indicator of stable air?
Which is an indicator of possible fire behavior problems?
Which is an indicator of possible fire behavior problems?
Study Notes
Topography and Fire Behavior
- Topography directly and indirectly influences combustible fuels and their availability for combustion.
- Among environmental factors affecting fire behavior, topography is the least variable.
Heat Transfer
- The least critical heat transfer method influencing wildland fire spread is conduction.
Fire Characteristics
- Ignition temperature is the heat required for self-sustaining combustion.
- Fireline intensity depends on fuel size, moisture, temperature, and compactness/arrangement.
Spotting and Crown Fires
- Long-range spotting requires wind and a developed convection column.
- Crown fires advance through tree canopies, while surface fires may produce torching and spotting.
Air Movement
- Upward moving air does not contract and warm; it expands and cools.
- As air sinks, it warms through increased pressure and compression.
Relative Humidity (RH) Dynamics
- In dry climates, lower nighttime temperatures result from reduced water vapor, which fails to retain heat.
- RH generally doubles with a 20°F decrease in temperature and halves with a 20°F increase.
- Lowest RH occurs at the highest temperatures.
Stability Indicators
- Stable air manifests in layers with clouds, while unstable air is characterized by gusty winds and vertically growing clouds.
Fire Behavior and Atmospheric Conditions
- Temperature generally decreases with elevation unless an inversion is present.
- Under stable air, fire activity generally decreases, and pollutants can accumulate under inversions.
- Unstable air often exists in low-pressure systems and can form through surface heating or upper air cooling.
Wind Effects
- Winds are named based on their originating direction, influencing fire spread.
- Foehn winds contribute to strong winds, warmer temperatures, and low humidity levels during wildland fires.
Fuel Characteristics
- Slope affects fuel availability; fuels are preheated during upslope movement.
- Aspect impacts moisture levels and vegetation types, influencing fire behavior.
- Fuel moisture content and size directly affect ignition, spread, intensity, and other fire behavior dynamics.
Timelag Fuel Categories
- Timelag categories (1-hour, 10-hour, etc.) denote the reaction time of dead fuels to moisture content changes.
- Fine dead fuel moisture is critical in determining ignition availability and fire spread, particularly in grass fuels.
Vegetation Development
- Vegetative stages are measured in percentages of moisture: 300%, 200%, 100%, 50%, and less than 30%.
- Cured cheatgrass reaches moisture of extinction faster during nighttime humidity recovery.
Monitoring Fire Indicators
- Key visual monitoring includes thunderstorm buildups, cloud types, and thermal air movement.
- Red Flag Warnings indicate combinations of fire danger factors like dry lightning, low RH, and unstable air patterns.
Wildfire Management Insights
- Effective firefighting involves recognizing fire behavior in three dimensions, including vertical movement and crowning phenomena.
- Factors for spotting problems include firebrand generation and transportation.
- Monitoring terrain and atmospheric conditions is crucial for effective fire response, with attention to features like steep slopes and wind patterns.
Fire Behavior Problems
- Indicators of fire behavior issues encompass phenomena such as well-formed smoke columns, crowning trees, and frequent spot fires.
- Continual observation of fuel hydration, meteorological conditions, and topography enhances firefighting efficacy.
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Description
Explore the critical factors influencing wildland fire behavior, including the role of topography, heat transfer methods, and fire characteristics. This quiz covers topics from spotting fires to air movement and relative humidity dynamics in the context of fire management.
