S-190 Exam Questions with 100% Correct
Answers
Wildland/Urban Interface
Line, area, or zone where structures and other human development meet or intermingle with
undeveloped wildland or vegetative fuels.
Convection Column
Rising column of heated air or gases above a continuing heat or fire source.
Fire Spread
Since there are 60 minutes in an hour and just over 60 ft. (18 m) in a chain, using the rule of
thumb will give you a reasonably accurate measurement of the fire's forward progress. For
example:
1 ft. (0.3 m)/minute = 1 chain/hour
10 ft. (3 m)/minute = 10 chains/hour
A fire that burns an area 10 chains by 10 chains is a 10-acre fire.
Conduction
When two objects of different temperatures contact each other directly or through a medium,
heat conducts from the warmer object to the cooler one until their temperatures equalize.
Convection
Hot convected gases moving up a slope can dry out fuels lowering their ignition temperature.
These fuels also become preheated by the convected heat, thus increasing their susceptibility
to ignition and more rapid fire spread.
Radiation
,1—Heat waves, sometimes called infrared rays, radiate in all directions from the heat source.
2—Heat waves travel through air until they are totally or partially absorbed by an opaque
object.
3—The opaque object gains heat and in turn radiates heat from its surface.
Aspect
The aspect of a slope determines the effect of the sun's heat on the slope's plants and trees, air
temperature, and moisture retention of the soil. Solar radiant heating can influence fire
behavior by influencing fuel moisture and ignition points. The southern slopes are more
susceptible to fires than northern slopes.
Slope
-Uphill side of a fire—flames are closer to the fuel dehydrating, preheating, and igniting them
sooner than they would if they were on level ground
-Wind currents normally move uphill during the day and tend to push heat and flames toward
new fuels
-Upslope fires create a draft, increasing the ROS. One serious concern about fires burning
down steep slopes is the possibility of burning material rolling downhill, which can ignite
fuels below starting another fire.
Calculating Slope
The percentage of slope is based on the ratio of vertical rise to horizontal distance.
To calculate a slope's percentage, follow these steps:
1. Measure the amount of vertical elevation change then...
2. Divide that number by the horizontal distance and...
3. To change the final number into a percent, multiply by 100.
, Saddle
Depression or pass in a ridgeline; low area on a ridgeline between two higher points.
Chute
A chute is a steep V-shaped drainage
Chimney
Steep, narrow draws or canyons in which heated air rises rapidly as it would in a flue pipe.
3 Types of Canyons
Box canyons
Narrow canyons
Wide canyons
Box Canyons
Air will be drawn in from the canyon bottom creating very strong upslope drafts. These
upslope drafts create rapid fire spread up the canyon, also referred to as the chimney effect
Narrow Canyons
Fire in a steep, narrow canyon can easily spread to fuels on the opposite side by radiation and
spotting. You can expect wind eddies and strong upslope air movement at sharp bends in the
canyon.
Wide Canyons
The direction, or orientation, of a canyon can alter the prevailing wind direction.
Fuel Groups
Answers
Wildland/Urban Interface
Line, area, or zone where structures and other human development meet or intermingle with
undeveloped wildland or vegetative fuels.
Convection Column
Rising column of heated air or gases above a continuing heat or fire source.
Fire Spread
Since there are 60 minutes in an hour and just over 60 ft. (18 m) in a chain, using the rule of
thumb will give you a reasonably accurate measurement of the fire's forward progress. For
example:
1 ft. (0.3 m)/minute = 1 chain/hour
10 ft. (3 m)/minute = 10 chains/hour
A fire that burns an area 10 chains by 10 chains is a 10-acre fire.
Conduction
When two objects of different temperatures contact each other directly or through a medium,
heat conducts from the warmer object to the cooler one until their temperatures equalize.
Convection
Hot convected gases moving up a slope can dry out fuels lowering their ignition temperature.
These fuels also become preheated by the convected heat, thus increasing their susceptibility
to ignition and more rapid fire spread.
Radiation
,1—Heat waves, sometimes called infrared rays, radiate in all directions from the heat source.
2—Heat waves travel through air until they are totally or partially absorbed by an opaque
object.
3—The opaque object gains heat and in turn radiates heat from its surface.
Aspect
The aspect of a slope determines the effect of the sun's heat on the slope's plants and trees, air
temperature, and moisture retention of the soil. Solar radiant heating can influence fire
behavior by influencing fuel moisture and ignition points. The southern slopes are more
susceptible to fires than northern slopes.
Slope
-Uphill side of a fire—flames are closer to the fuel dehydrating, preheating, and igniting them
sooner than they would if they were on level ground
-Wind currents normally move uphill during the day and tend to push heat and flames toward
new fuels
-Upslope fires create a draft, increasing the ROS. One serious concern about fires burning
down steep slopes is the possibility of burning material rolling downhill, which can ignite
fuels below starting another fire.
Calculating Slope
The percentage of slope is based on the ratio of vertical rise to horizontal distance.
To calculate a slope's percentage, follow these steps:
1. Measure the amount of vertical elevation change then...
2. Divide that number by the horizontal distance and...
3. To change the final number into a percent, multiply by 100.
, Saddle
Depression or pass in a ridgeline; low area on a ridgeline between two higher points.
Chute
A chute is a steep V-shaped drainage
Chimney
Steep, narrow draws or canyons in which heated air rises rapidly as it would in a flue pipe.
3 Types of Canyons
Box canyons
Narrow canyons
Wide canyons
Box Canyons
Air will be drawn in from the canyon bottom creating very strong upslope drafts. These
upslope drafts create rapid fire spread up the canyon, also referred to as the chimney effect
Narrow Canyons
Fire in a steep, narrow canyon can easily spread to fuels on the opposite side by radiation and
spotting. You can expect wind eddies and strong upslope air movement at sharp bends in the
canyon.
Wide Canyons
The direction, or orientation, of a canyon can alter the prevailing wind direction.
Fuel Groups
