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 the 'dew point' and why is it important to wildland firefighters?
Answer: The temperature at which air becomes saturated and moisture condenses, indicating atmospheric humidity
Dew point is the temperature at which air becomes fully saturated with moisture; a low dew point means dry air, which dries fuels and promotes more aggressive fire behavior.
How does a 'cold front' passage typically affect ongoing wildland fire behavior?
Answer: It can cause erratic, gusty winds and rapid wind shifts before conditions eventually moderate
Cold front passage often produces gusty, shifting winds ahead of and during passage that can dramatically and unpredictably alter fire behavior before cooler, more stable air arrives.
Which of the following best describes 'fine fuels' in the context of fire behavior?
Answer: Small diameter dead fuels (grasses, pine needles) that dry and ignite quickly
Fine fuels are small-diameter dead materials (typically under 1/4 inch) like grasses, leaves, and pine needles that respond rapidly to moisture changes and ignite and burn quickly.
What does 'rate of spread' (ROS) measure in wildland fire behavior?
Answer: The speed at which the fire perimeter advances across the landscape
Rate of spread measures how fast the fire's head or perimeter advances, typically expressed in chains per hour or feet per minute, directly affecting firefighter safety decisions.
During Red Flag Warning conditions, which combination of factors is typically present?
Answer: Low relative humidity, high winds, and critically dry fuels
Red Flag Warnings are issued when relative humidity is very low (often below 15%), winds are high, and fuels are critically dry—conditions that support rapid fire growth and extreme behavior.
What is 'torching' in wildland fire behavior terminology?
Answer: Individual trees or small groups igniting and burning from crown to base
Torching occurs when the foliage of an individual tree or small group of trees ignites and burns intensely, often generating firebrands and indicating transition toward crown fire conditions.
How does relative humidity (RH) below 25% affect dead fine fuel moisture in wildland fires?
Answer: Fine fuels quickly equilibrate to critically low moisture levels, significantly increasing ignitability
Dead fine fuels rapidly equilibrate with surrounding air humidity; RH below 25% drives fine fuel moisture to critically low levels (often below 6-8%) that support rapid ignition and spread.