FIRE

Fire – The rapid combination of oxygen, hydrogen, and other elements of organic material in a reaction that produces flame, heat, and light.

Photosynthesis 6CO 2 + 6h light  C 6 H 12 O 6 + 6O 2 (energy) (chemical energy)

Fire C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + heat (chemical energy) (energy)

Chemically, Fire = respiration

Also, fire = decomposition

The fuel of wildfires is all of the stored chemical energy produced in photosynthesis

Fire is necessary In some environments, decomposition cannot keep up with the production of plant material.

Fire recycles nutrients and regenerates plant communities.

Is there a problem with fighting all wildfires?

2009 Statistics from the CDC 2565 deaths, mostly from smoke and toxic gases, not burns. 85% in homes

Wildfires are almost all started by humans or lightning.

Fire Tetrahedron

Fuel  Starve the fire

Heat  Cool the fire

Oxygen  Smother the fire

Sustaining chemical reaction  Interfere in the chemical chain reaction

Fuel Categories Grasses Shrubs Trees Slash Ladder fuels – when liter and shrubs act as a ladder for fire to climb up into the crowns of trees.

Pyrolysis Flaming combustion – When wood surface heats up to ~325 0 C (615 0 F), it breaks down and produces gases that support flames.

Glowing combustion – produced from the wood itself actually burning.

Spread of Fire Fuel – Energy release in a fire depends on chemical composition of plants and organic debris. Example: oils of eucalyptus trees.

Wind – strong wind causes… 1.Continuous supply of oxygen to the fire. 2.Pushes flames and heat towards more fuel. 3.Produces firebrands that can start spot fires.

Topography – Fire moves faster upslope.

Fire Behavior 1.Fire causes hot, unstable rise of air. 2.This can produce fire tornadoes with winds of up to 250kph (150mph).

Fire Weather What kind of weather patterns produce the greatest fire hazard?

Cold fronts – As cold fronts move through the West in summer, they may produce lots of lightning but little rain.

Strong high pressure over the Great Basin or Rocky Mountains.

Chinook winds in the Rockies. Santa Ana winds in California.

What type of climate pattern produces the greatest fire hazard?

Peshtigo, Wisconsin – worst forest fire in U. S. history. On that same day, Oct. 8, 1871, the great Chicago fire started.