S-190 Principles of Wildland Fire Behavior Latest Update with Certified Solutions
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Course
S-290
Institution
S-290
S-190 Principles of Wildland Fire Behavior Latest Update with Certified Solutions
Wildland Fire -️️ Unplanned and unwanted fire requiring suppression action; an uncontrolled fire, usually spreading through vegetative fuels. These fires can threaten structures or other improvements
Fire Behavi...
S-190 Principles of Wildland Fire Behavior Latest Update with Certified Solutions Wildland Fire -✔️✔️ Unplanned and unwanted fire requiring suppression action; an uncontrolled fire, usually spreading through vegetative fuels. These fires can threaten structures or other improvements Fire Behavior -✔️✔️ Manner in which a fire reacts to the variables of fuel, weather, and topography Topography -✔️✔️ Land surface configuration Crew -✔️✔️ Organized group of firefighters under the leadership of a crew leader or other designated supervisor; sometimes referred to as a "company" in municipal departments Aspect -✔️✔️ Compass direction toward which a slope faces Slope -✔️✔️ - Natural or artificial topographic incline; degree of deviation from horizontal - fires typically move faster going uphill than downhill - flames are closer to the fuel dehydrating, preheating, and igniting them sooner - 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 Barrier -✔️✔️ Any obstruction of the spread of fire; typically an area or strip devoid of combustible fuel Fireline Intensity -✔️✔️ Rate of heat energy released per unit time per unit length of fire front. Numerically, it is the product of the heat of combustion, quantity of fuel consumed in the fire front, and the rate of spread of a fire in Btu per second per foot (kilojoules per second per meter) of fire front Rate of Spread (ROS) -✔️✔️ relative activity of a fire in extending its horizontal dimensions. expressed as rate of increase of the total perimeter of a fire, as rate of forward spread of the fire front, or as rate of increase in area, depending on the intended use of the information. usually expressed in chains or acres per hour for a specific period in the fire's history North Facing Slopes -✔️✔️ tend to have more shade. as a result north facing slopes have heavier fuels, lower temperatures, higher humidity, and higher fuel moistures. a north facing aspect will have less fire activity than a south facing slope East Facing Slopes -✔️✔️ eastern and southern slope exposures have about equal solar heating as the sun moves across the sky from east to west. with sunrise, east facing slopes will have earlier heating, but also earlier cooling as the sun tracks across the sky West Facing Slopes -✔️✔️ similar to eastern and southeastern slopes, southwestern, and western slops exposures have about equal solar heating as the sun moves across the sky from east to west. west facing slopes will have later heating and cooling during the course of the day South Facing Slopes -✔️✔️ in the northern hemisphere, the slopes facing south receive direct sun rays and become hotter than slopes facing any other direction. the higher temp on the souther exposures results in lower humidity, rapid loss of fuel and soil moisture, and drier, lighter flashy fuels such as grass. all of these things make southern slops more susceptible to fires than northern slopes Concerns of Downhill Burning -✔️✔️ - serious concern is the possibility of burning material rolling downhill, which can ignite fuels below starting another fire - fighting fires on a steep slope demands your undivided attention Safety Zone -✔️✔️ recently burned area or one cleared of vegetation used for escape in the event a line is outflanked or a spot fire outside a control line renders the line unsafe. in firing operations, crews progress so as to maintain a safety zone close at hand, allowing the fuels inside the control line to be consumed before going ahead. sometimes called safety island or safe refuge Escape Routes -✔️✔️ pathway to safety. it can lead to an already burned area, a previously constructed safety area, a meadow that will not burn, or natural rocky area that is large enough to take refuge without being burned. when escape routes deviate from a defined physical path, they must be clearly marked Slope Measurement -✔️✔️ - "rise over run" 1.) measure the amount of vertical elevation change 2.) divide that number by the horizontal distance 3.) the 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 steep V -shaped drainage and a saddle is a common name for the depression between two adjacent hilltops Chutes and Saddles Can? -✔️✔️ - drastically accelerate fires - alter the flow of winds causing erratic fire behavior - change the rate and direction of spread by acting as chimneys Chimneys -✔️✔️ steep, narrow draws or canyons in which heated air rises rapidly as it would in a flue pipe Box Canyons -✔️✔️ fires starting near the base of box canyons and narrow canyons may react similar to a fire in a wood burning stove or fireplace. 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
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