Fire Behavior & Weather Flashcards
7 cards from real S-130 practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Fire Behavior & Weather flashcards as text
What is the primary cause of the 'afternoon peak' in fire danger that typically occurs between 2:00 PM and 4:00 PM?
Answer: Maximum temperature combined with minimum relative humidity creates the most critical fire weather conditions
The afternoon peak in fire danger results from daily maximum temperatures and minimum relative humidity occurring simultaneously, creating the driest and most ignition-prone conditions.
How do 'fuels' in the context of the fire triangle contribute to fire behavior intensity?
Answer: The quantity, arrangement, moisture content, and type of fuels all directly influence fire intensity and rate of spread
Fuel characteristics including quantity, continuity, moisture content, size, and arrangement collectively determine how much energy a fire releases and how fast it spreads.
What phenomenon causes fires to burn more intensely and spread faster on steep slopes?
Answer: Slope preheats uphill fuels through convective and radiant heat, and chimney effect accelerates uphill spread
On steep slopes, heat rises and preheats fuels above the fire, and the chimney effect channels hot gases uphill, dramatically accelerating the rate of spread up the slope.
What is 'crowning' in wildland fire behavior?
Answer: Fire that moves through the tops of trees independently of or in conjunction with surface fire
Crowning occurs when fire moves through the tree canopy and can be passive (dependent on surface fire) or active (self-sustaining), and is associated with extreme rates of spread.
Which wind pattern is most commonly associated with dangerous Foehn (downslope) winds in the western United States?
Answer: Dry, warm air that compresses and heats as it descends the leeward side of a mountain range
Foehn winds (called Santa Ana in Southern California) are dry, warm winds created when air descends and compresses on the leeward side of mountains, dramatically reducing humidity and increasing fire danger.
In the context of wildland fire, what does 'backing fire' mean?
Answer: A fire spreading into the wind or downhill, moving slowly with lower intensity
A backing fire spreads against the wind or downhill, resulting in slower spread rates, lower flame lengths, and generally lower intensity than head fire or flanking fire.
What is the significance of 'critical fire weather' as defined in S-130 training?
Answer: A combination of low humidity, high temperature, and strong winds that dramatically increases fire danger
Critical fire weather refers to the combination of low relative humidity (typically below 25%), high temperatures, and strong or erratic winds that create extreme fire behavior potential.