Wildfire

Origen: A fire that starts in the wild land
- Depends on origin:
  - Bush fire
  - Brush fire
  - Desert fire
  - Forest fire
  - Grass fire
  - Hill fire
  - Peat fire
  - Vegetation fire (Veld fire)
- Trigger: Human activities, agriculture, Arson, cigarettes, lightning, Sparks from something, Spontaneous combustion and volcanic eruptions
  - Cause of ignition, physical properties, combustible and weather
- Behavior: Fast onset and might be difficult to get away
- Place: All dry areas; Common in summer season
Other: It is possible to predict potential risk, and estimate the onset
- Fire triangle: Oxygen, Fuel (combustible material) and Heat
  - Heat create fire, but a higher temperature is needed to evaporate water
- Wildfire front: Where unburned meets flames
- Smoldering transition: Between unburned and burned
- Heat transfer: 800 degrees C in front of a wildfire front; materials ignite faster
- Flashover/ torching: Dry tree canopies; ignite faster
- Wood:
  - Water vaporizes at 100 degrees C
  - Pyrolysis at 230 degrees C: creates flammable gases
  - Smolder at 380 degrees C
  - Ignite at 590 degrees C
- Precaution:
  - Need flammable materials to spread:
    - Four types:
      - Ground (roots, duff and organic matter)
      - Crawling/ surface (low-lying vegetation)
      - Ladder (small threes etc)
      - Crown/ Canopy/ aerial (tall threes etc)
    - Forward rate of spread (FROS):
      - Forest: 10.8 km/h
      - Grassland: 22 km/h
      - Spread faster during day: 5 x
    - Stark effect: The heat creates wind: 80 km/h; fire spreads faster
    - Fires starts more frequent between 12.00 and 14.00
      - A fire day starts at 10.00 in the morning and last 24 hours
    - Closedown of Society: Fast and relatively long lasting

Del dette: