Fire Behavior & Weather Flashcards
7 cards from real RED CARD 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
Which fuel moisture level is considered critically dry and significantly increases fire danger?
Answer: Below 15%
Live fuel moisture below 15% is critically dry and represents extreme fire danger with rapid fire spread potential.
What is a 'fire whirl' and why is it dangerous to firefighters?
Answer: A spinning vortex of fire that can unpredictably change direction and carry embers long distances
Fire whirls are rotating columns of fire created by intense heat and turbulent winds that can move erratically and loft burning material far ahead of the main fire.
During a temperature inversion, how does smoke and fire behavior typically change?
Answer: Smoke is trapped near the ground and fire behavior is generally more moderate
Temperature inversions trap cooler air and smoke near the surface, suppressing convective columns and generally moderating fire behavior until the inversion breaks.
What does the term 'spotting distance' refer to in wildland fire behavior?
Answer: The distance burning embers are carried ahead of the main fire front
Spotting distance is how far firebrands (burning embers) are transported by wind or convection columns beyond the main fire, creating new ignition points.
Which type of wind shift is most dangerous for firefighters working near a fire's flanks?
Answer: A sudden 90-degree shift that converts a flank into a head
A 90-degree wind shift can instantly turn a slow-moving flank into a fast-advancing head fire, trapping firefighters who were working what seemed like a safe position.
What is the primary reason fire spreads faster uphill than on flat terrain?
Answer: Flames tilt toward unburned fuel on slopes, preheating it through radiation and convection
On slopes, flames lean toward the unburned fuel uphill, significantly increasing preheating through direct flame contact, radiation, and convection, accelerating spread rate.
What weather condition is associated with 'Haines Index' values of 5 or 6?
Answer: Very high potential for large fire growth due to dry, unstable atmosphere
A Haines Index of 5-6 indicates very high to extreme potential for large fire development based on atmospheric stability and moisture deficit in the lower atmosphere.