Pg. 57

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Pg. 57 The discovery of controlling fire made
it an early technology. Examples of Fire use
today constructive -used for our
benefic destructive -causing us grief ADD Fire
triangle Fire is oxidation in action .....
combustion is the rapid reaction of oxygen and
organic material burning wood produces carbon
dioxide, water and heat
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Pg. 57 STAGES OF FIRE 1. Preheating (starting
the fire) a) water removed from
plant/organic material b) temperature of
material increases pyrolysis (chemical
structure of wood breaks down yields flammable
components) 2.) Flaming combustion stand
back!!! burninglots of energy released 3.)
Glowing combustion no flames but those embers
are hot! FIGURE LINK
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Pg. 57 HOW DOES FIRE SPREAD? 1) slowly along
the ground glowing combustion dominates 2)
wall of fire - flaming combustion dominates 3)
crown fire -fire in tree tops similar to wall of
fire just in the tree trops ADD Ladder Fuels
-stepping up from one fuel level to the
next. ND pg. 407 Fig. 14.2
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Pg. 58 WHAT HELPS THE SPREAD OF FIRE? 1) Wind -
pushes fire, feeds with oxygen 2) Fuel Type of
vegetation burning how much Oils in wood
(eucalyptus) highly flammable (chaparral) vs.
flame resistant a.) Branches close to ground
or not b.) Lots of shrubby under
story Remember ladder fuels. c.) Slash-
brush piles left from clearing vegitation 3)
Moisture - wet or dry and for how long
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Pg. 58 WHAT HELPS THE SPREAD OF FIRE? 4)
Topography of land - hills - fire burns faster up
slope - (convection heat rises so
preheats)- topography effects vegetation
types 5) Positive feedback - fire creates
unstable air and may create fire tornado-carry
burning debris and start new fires. Heat rises,
sucks in oxygen from sidesmore
combustion-compare to in space to the make
point Positive Feedback is a Vicious Cycle but
it is positive?
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ADD pg. 58 HOW DO HOMES CATCH ON FIRE? 1.)
Physical contact -Flames travels right to
home 2.) Radiant heat causes home materials to
ignite. warming your hands but be
careful Flames do not have to touch the
house. 3.) Firebrands- glowing embers blown by
the wind to new areas.
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ADD pg. 58 WHAT TO DO. 1.) HOME DESIGN A.)
set back from top of slope- 100 ft minimum. ND
pg. 420 fig. 14.25 B.) building materials
-flammable vs. nonflammable C.) design- no
overhanging decks/eaves D.) wide, easily
accessible driveways E.) Roof- fire proof
because of firebrands ND pg. 419 fig.
14.23 WHY?? on all
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ADD pg. 58 WHAT TO DO. 1.) LANDSCAPING A.)
keep a 30 barrier around home B.) Keep trees
trimmed (side and over roof) C.) use fire
resistant plants -succulent ice plant ND pg.
421 fig. 14.26 D.) Keep surrounding forest
thin-ladder fuels- remove ground level that
could spread to crown E.) keep slash -dead
stuff cleared out. Results ND pg. 418 fig.
14.22
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Pg. 58 WHERE DO FIRES OCCUR? General
Trend Regions that experience wet and dry
seasons (wetplant growth dryfire) Drought
areas Examples 1.) Great Lakes 1871 clearing
fields for ag. use lots of wood debris left.
Long dry spell. Strong winds. Result - huge
area burned farms and towns Peshtigo, WI wall
of flames moved fast 1100 casualties
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Pg. 59 2.) Chicago, IL-Oct. 8, 1871 Legend Mrs.
OLearys cow kicked a lantern over wind
whipped flames - heart of the city burned, 300
casualties. ADD 1.) Unusually dry summer 2.)
City had just finished building sidewalks out of
wood
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• Pg. 59
• 3.) CALIFORNIA ( S.F. and S. Calif.) is a
  location
• where fire is always a hazard certain times of
  year.
• WHY?
• vegetation type (chaparral - very flammable
• fire species - need fire to reseed)
• b) hilly - fire races uphill- CONVECTION
• c) homes built close to vegetation and on steep
  hills
• d) drought not uncommon
• e) warm winds common
• f) people/wacko in the woods - can start fires -
  arsonist

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ADD pg.59 Baja vs. Southern California Southern
California 1.) Fires in the early, cooler, wetter
season are put out quickly-allows maximal plant
growth. 2.) This leaves (not intended) lots of
highly flammable chaparral to burn in the drier
autumn. 3.) Fires are fought energetically and
with lots of a.) leaves behind dense
overgrowths of chaparral. b.) as chaparral grows
it becomes more flammable. 4.) Warm, dry winds
occur in autumn when we have lots of
fuel RESULTS leaves lots of flammable fuel for
the hot dry season
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ADD pg.59 Baja vs. Southern California Baja 1.)
Fires are NOT fought energetically and with
little a.) leaves little overgrowth of
chaparral. b.) as chaparral grows it becomes
more flammable. SO. We have less chaparral AND
it is less flammable. 2.) Warm, dry winds occur
in autumn BUT dont have much fuel to feed
fires. RESULT less fuel during the hot dry
autumn.
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ADD pg.59 Baja vs. Southern California
Total Area Area Burned Burned Burned After Sept. 1 Number of Fires
S.C. 2,019 166 8.2 72 203
BAJA 1,202 95 7.9 20 488
1000s hectares
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ADD pg.59 Baja vs. Southern California
Distribution 1.) S.C. a few biggies-and burns
higher 2.) Baja a bunch of little ones ND pg.
424 fig.14.28 BIG QUESTION Should we continue
to fight big fires or let the early season fires
go more?
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Pg. 59 IF YOU LIVE IN A FIRE PRONE AREA WHAT
CAN YOU DO? 1.) Build for fire NO Wood roof,
wood house, wood deck, no. veg. near house
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QUIZ 1.) Which of the following best describes
the southern California case history (compared
to Baja) a.) let little fires burn b.) fight
little fires c.) spend little money fighting
fire d.) results in a small amount of flammable
material for the hot dry season 2.) Why are
fires a continual hazard in southern
California? A) older vegetation resists burning
B) moist conditions are common C) homes on
hillsides D) cool moist winds are common
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• QUIZ
• 3.) Which of the following best represents the
  safest
• course of action when designing landscaping
• a.) 50 setback from top of slope and dense
  underbrush
• b.) fire wood stored near the house and a 30
  barrier
• surrounding the house
• c.) trimming overhanging trees and removing
  slash(debris)
• d.) building on top of a hill and planning up to
  the house
• 4.) Which of the following is significant in
  aiding the spread of fires
• A) types of vegetation and topography
• B) size of house and building material
• C) number of rivers in area and moisture
• how many lakes there are in an area and fuel

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• QUIZ
• 5.) What best describes how convection causes
  burning
• A) Heat rises and fire burns up hill
• B) Heat rises and fire burns down hill
• C) Heat sinks and fire burns up hill
• D) Heat sinks and fire burns down hill
• 6.) What best describes how radiation causes
  burning?
• The fire has to physically touch the side of the
  house
• B) The heat of the fire has to rise uphill to the
  house
• C) Firebrands drift onto new areas causing new
  small fires
• D) The flames give off energy that begins to warm
  things
• around it without touching them

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QUIZ 7.) What best describes the conditions in
the Great Lakes region in 1871 A) Dry, high
winds, high topography B) Dry, low winds, high
topography C) Dry, high winds, low topography D)
Dry, low winds, low topography 8.) Which of the
following best describes a fires
positive feedback behavior? A) a fire burning
down hill causing less burning B) A fire sends
out firebrands causing the fire to get bigger
and bigger C) moist air causing less burning D) a
fire running out of fuel
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QUIZ 9) What contributed to the Chicago fires of
1871? A) wooden sidewalks, dry conditions, and a
cow B) wooden sidewalks, moist conditions, and a
cow C) stone sidewalks, dry conditions, and an
ostrich D) wooden sidewalks, dry conditions, and
an ostrich