S-290 (WEEK 4) Flashcards
U.1
(True / False) Topography can directly and indirectly affect furls and their availability for combustion.
True
U.1
Of the three primary environmental factors that influence fire behavior, which is the least variable?
Geography
U.1
The least critical form of heat transfer that influences rate of spread in a running wildland fire is:
Conduction (is the least)
U.1
The point to which a combustible material must be heated to produce self sustaining combustion is known as the:
Ignition temperature
U.1
Fireline intensity is dependent upon:
1- Fuel size 2- Fuel moisture 3- Fuel temperature 4- Fuel compactness and arrangement ***(All Of The Above)***
U.1
(True / False) Two requirements for long-range spotting are wind and well developed convection column.
True
U.1
A fire that advances through canopies of brush and trees is known as a:
Crown fire
U.1
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.
Surface fire with torching and spotting
U.1
Fire begins burning into the crowns and spreads through the canopy. There is a sudden increase in fireline intensity where the fire controls its environment. At one point flames can be seen carried high into the convection column with a whirling motion.
Crown fire with convention column and firewhirls
U.1
Fire is consuming the organic materials beneath the surface of the ground after the main fire has passed through and is spreading on the surface without flames. Occasionally the fire will ignite areas of unburned fuels on the surface and short fire runs take place.
Ground fire with smoldering and flare ups
U.2
(True / False) Upward moving air contracts and warms.
False
U.2
As air sinks, it:
Increases in pressure; warms and compresses
U.2
Why do dry climates usually have lower nightime temperatures than humid climates?
a
U.3 (Attachment)
Using the relative humidity table attached, what is the relative humidity at 1,200’ elevation when the dry bulb temperature is 76F and the wet bulb is 57F?
a
U.3 (Attachment)
Using the relative humidity table attached,
a
U.3
At 0930hrs, you have the following information; The dry bulb temperature is 65F and wet bulb is 46F. What will the minimum afternoon relative humidity be if the forecast maximum temperature is 83*F and the location is 1200’?
a
U.3
(True / False) On the average the relative humidity doubles with each 20* F decreases of temperature, or halves with each 20* F increase in temperature.
True
U.3
(True / False) The lowest relative humidity occurs with the highest temperature.
True
U.3
(True / False) Relative humidity is usually lower on north aspects.
False
U.3
(True / False) Cloudiness has little affect on relative humidity and temperature.
False
U.3
(True / False) The type of vegetation has little affect on temperature and humidity.
True
U.3
(True / False) Relative humidity measures the amount of moisture in the air.
True
U.4
Clouds form in layers.
Stable
U.4
Gusty winds.
Unstable
U.4
Smoke Column spreads out after limited rise.
Stable
U.4
Clouds grow vertically.
Unstable
U.4
Firebrands are lifted into convection column.
Unstable
U.4
(True / False) Temperature decreases with an increase in elevation when an inversion is present.
False
U.4
What is the general effect of stable air on wildland fires?
Fire activity decreases
U.4
What conditions will occur under a surface inversion during the morning hours?
1- Temperatures are cool, winds are calm or light
2- Fire activity decreased 3- Pollutants can accumulate under inversions
(All Of The Above)
U.4
What are the different lifting processes that can lead to thunderstorm development?
Frontal, orographic, thermal, convergence
U.4
(True / False) Unstable air can often be found in low pressure systems and on the leading edge of cold fronts.
True
U.4
(True / False) Unstable air can be formed by either heating the air near the ground or by cooling the air aloft.
True
U.5
Wind direction is:
The direction the wind is blowing from.
U.5
A slope wind is caused by:
Warm air rising and cold air settling.
U.5
Foehn winds can adversely affect wildland fires because they can produce:
Strong winds
U.5
When stable air is forced over a mountain range, and then descends the leeward slopes as dry, warmed air, it is called:
A foehn wind
U.5
(True / False) Bends in canyons are likely places for wind eddies to form.
True
U.5
Local winds are best defined as:
Small scale
U.5
East, Mono, Santa Ana, and Chinook are all examples of
Foehn Winds
U.5
(True / False) Air flows clockwise around low pressure systems and counterclockwise around high pressure systems.
False
U.6
Slope affects fuel availability to burn because:
Fuels are preheated upslope through radiation and convection; and Rolling firebrands ignite new fuels below (Both A and B)*
U.6
Select the correct statement regarding the shape of the country and its effect on wildland fire behavior.
The shape of the country can influence the curing of fuels as well as the intensity and spread of wildland fires.
U.6
Aspect affects fuels and their availability to burn because…
- Southwest slopes provide drier sites
- Vegetation type and fuel moisture content changes by aspect
- Shading on northern aspects can increase relative humidity
- *ALL OF THE ABOVE**
U.6
Select the statement that best describes the effect of slope steepness on fuel availability.
A fire starting at the base of a slope has more fuel available for spread
U.7
A fuel model is defined as….
A set of numbers that define fuel input for use in the surface fire spread model
U.7 The four (4) fuel groups defined in the fire behavior prediction system (FBPS) are:
Grass, shrub, timber, litter and logging slash
U.7
Available fuels are:
All dead and live fuels that will ingnite and continue to burn
U.7
Fuel loading:
The oven-dry weight of fuel in an given area, expressed in tons/acre or pounds/acre.
U.7
Fuel moisture content:
The amount of water in a fuel expressed as a percent of the oven-dry weight of that fuel
U.7
Fuel size and shape:
The surface-area to volume ratio
U.7
Fuel chemical content:
The presence of volatile substances in a fuel
U.7
Which of the following fuel characteristics affect all six wildland fire behavior concerns: ie ignition, spread, intensity, spotting, torching, and crowning?
Moisture content
U.7
Which fuel has the higher surface-area-to-volume ration?
GRASS
U.7
The 1-hour timelag fuel category is:
0.0 to 1/4inch in diameter
U.8
Fuel moisture timelag can best be described as:
The rate at which dead fuel gains or loses moisture
U.8
One hour timelag fuel moisture is used in fire behavior calculations to determine:
Whether large fuels are available for ignition and fire spread
U.8
The five stages of vegetation development for live fuel moistures are:
300%, 200%, 100%, 50% and less than 30%
U.8
The following statement best describes timelag fuel categories:
1 hour timelag fuels react to changes in relative humidity much faster than 100 hour fuels
U.8
(True / False)
Foehn winds always cause fuels to gain in moisture content.
FALSE
U.8
(True / False)
Dead grass reacts like a 1-hour timelag fuel.
TRUE
U.8
The fuel moisture at which fire will not spread is the:
Moisture of extinction
U.8
Inputs used to determine fine dead fuel moisture content are:
Time of day, month of year, dry bulb temperature, relative humidity, aspect, percent slope, shading of surface fuels
U.8
It is September 10, at 1000hours. Fuels are unshaded on an east aspect, 20% slope. Weather observations taken at the site are: Dry bulb temp. 81*F, relative humidity 14%. The fine dead fuel moisture is:
4%
U.8
It is Nov. 4 at 1600hours. Fuels are shrub on a west aspect, 35% slope. Weather observations taken at your location are: Dry bulb temp. 68*F. relative humidity 23% and cloud cover shading the fuels. The fine dead fuel moisture 1300 feet below you is:
8%
U.8
(True / False)
Only the 1000-hour timelag fuel moistrure is used when making wildland fire behavior predictions.
FALSE
U.8
Select the fuel complex that would reach its moisture of extinction first during nighttime humidity recovery.
Cured cheatgrass
U.9
If the wet bulb is not read at its lowest point, what will happen
The calculated relative humidity will be too high
U.9
What weather processes can and should be monitored visually?
- Thunderstorm buildups
- Clouds
- Approaching cold fronts
- Indications of a stable or unstable air
ALL OF THE ABOVE
U.9
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?
Strong shifting winds
U.9
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:
- Dry lightning
- Lightning following an extremely dry period
- Unusually low relative humidity
- Very dry and unstable air
ALL OF THE ABOVE
U.9
Spot weather forecasts are:
Forecasts that are issued to fit the time, topography and weather of a specific location
U.10
Initiate action based on ________ fire behavior.
Current and expected
U.10
Fire which can generally be attacked at the head or flanks by persons using hand tools have flame lengths that are _________.
Less than 4 feet
U.10
(True / False)
Effective windspeed is the midflame increased for the effect of slope on fire spread.
FALSE
U.10
The surface fire characteristic charts relates __________.
Rate of spread and flame length
U.10
(True / False)
Regardless of fine dead fuel moisture percentage, rate of spread is determined by the live fuel moisture.
FALSE
U.10
En route to a fire you notice that smoke from burning haystack rises straight up. What could this indicate on a wildland fire:
An unstable atmosphere may increase fire activity
U.10
A ground fire has burned under a thick stand of pine reproduction. What potential problems could occur?
A reburn possibly involving the canopies
U.10
You are on a fire in the coast range of Southern California. The fire is burning above you on the slope. At 1800 hours you experience a sudden calm in the sea breeze. What might you next expect to occur?
Wind may shift to downslope with possible foehn wind surfacing
U.10
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?
B) Expect moderate to long range spotting downwind
C) Strong winds aloft could surface on the fire
BOTH B and C are CORRECT
U.11
Wildland fire behavior in the third dimension:
- Presents a vertical dimension to fire suppression
- Exhibits crowning, spotting and vortex phenomena
ALL OF THE ABOVE
U.11
Four factors that are responsible for the occurrence of fire behavior in the third dimension are:
Available fuels, wind, high atmospheric moisture and instability
U.11
Three stages of crown fire development are:
1- Passive
2- Active
3- Independent
U.11
(True / False)
Crown fire development depends on crown flammability along with adequate surface-to-crown and crown-to-crown heat transfer.
TRUE
U.11
The factors that contribute to the spotting problem can be classified into three general areas….
1- Firebrand source
2- Transportation
3- The receiving fuel
U.11
Probability of ignition is determined by:
Fuel shading, fine dead fuel moisture percent and dry bulb temperature
U.11
With a fine dead fuel moisture of 8%, a dry bulb temp of 92*F and a cloud cover of 70&, what is the probability of ignition?
40
U.11
(True / False)
Vortices are grouped as vertical or horizontal depending on their axis of rotation.
TRUE
U.11
When the wildland fire environment is dominated by a ______ fire, the convection column overpowers the wind field.
Plume-dominated
U.12
(True / False)
Continuous fine fuels, heavy fuel loadings, ladder fuels, crown spacing and special fuel situations are fuel characteristics that should NOT be monitored.
FALSE
U.12
(True / False)
Low relative humidity and a high 1000 hour timelag fuel moisture are both critical fuel moisture indicators that should be monitored.
FALSE
U.12
(True / False)
Steep slopes, chutes, saddles and narrow canyons are terrain indicators that should be monitored.
TRUE
U.12
(True / False)
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 wildland firefighters.
FALSE
U.12
Which of the following is an indicator of stable air?
Inversion
U.12
Which is an indicator of possible fire behavior problems?
- Leaning, sheared, or well-developed smoke column
- Trees crowning
- Firewhirls beginning
- Frequent spot fires
- ALL OF THE ABOVE*
