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
What is a 'chimney' terrain feature and why does it pose extreme danger to firefighters?
Answer: A steep, narrow drainage or draw that funnels and accelerates fire uphill like a flue
Chimneys are steep, narrow drainages that act like flues, channeling and accelerating fire uphill at extreme speeds while blocking escape routes for firefighters working inside them.
What is the primary function of a 'convective column' in a large, active wildland fire?
Answer: It draws in surface air from all directions to feed combustion and can transport firebrands long distances aloft
A convective column (or smoke column) draws in oxygen-rich air from surrounding areas to sustain combustion and can loft burning embers miles ahead of the fire through its updraft.
Which atmospheric condition causes a 'blow-up' fire or extreme fire behavior event?
Answer: Unstable atmosphere with low humidity, strong winds, and critically dry fuels combining to create rapid, explosive fire growth
Blow-up fires result from an unstable atmosphere combined with low humidity, strong winds, and dry fuels interacting to produce sudden, extreme fire growth that can overwhelm suppression efforts.
How does a 'thermal belt' affect nighttime fire behavior in mountainous terrain?
Answer: It is a mid-slope zone of warmer temperatures and lower humidity that maintains active fire behavior overnight
Thermal belts occur at mid-slope elevations where cold air drainage prevents temperature from dropping as much as in valleys or ridges, keeping relative humidity lower and fire more active at night.
What is 'dead fuel moisture' and how does it differ from 'live fuel moisture'?
Answer: Dead fuel moisture reflects equilibrium with atmospheric humidity; live fuel moisture reflects physiological water content of living plants
Dead fuel moisture equilibrates with ambient air temperature and humidity, while live fuel moisture depends on plant physiology and seasonal drought stress, making them respond to weather on very different timescales.
Under which condition does 'crown fire' most likely transition from passive to active (running) crown fire?
Answer: When surface fire intensity is sufficient to continuously ignite crown fuels and winds carry the fire from crown to crown
Active (running) crown fire occurs when wind is strong enough to continuously spread fire through the canopy and surface fire intensity is sufficient to maintain that crown ignition without relying on individual tree torching.
What is the significance of the '1 o'clock fuel moisture' reading in daily fire weather monitoring?
Answer: It captures fuel moisture near the peak drying period of the day when fire danger is typically greatest
The 1 o'clock (1300 hours) fuel moisture sample is collected near peak afternoon heating and minimum humidity, representing the most critically dry fuel conditions of the day.