Fire Behavior Terminology

  • Smoldering: no flame, barely spreading
  • Creeping: low flame and slow spread
  • Flame Length: length from base to tip, not vertically
  • Rate of Spread: chains per hour = feet per minute
  • Running: definite flames, rapid spread to surface fuels with well-defined head
  • Torching: fire runs up ladder fuels into crowns of individual trees, no spread from crown to crown
  • Crowning: fire spreading from crown to crown, either dependent or independent of surface fire

Fuels Observations

  • 1 hour – less than ¼ inch diameter
  • 10 hour – ¼ inch to 1 inch diameter
  • 100 hour – 1 inch to 3 inch diameter
  • 1000 hour – > 3 inch diameter

Fire Severity Related to Relative Humidity & Fuel MoistureFire Severity Related to Fuel Moisture