Fire Exam 2

What are the 3 components of the fire triangle?

Heat

Fuel

Oxygen

What is fire?

Rapid exothermic combustion between a fuel and an oxidant that releases energy + byproducts

What is the current composition of Earths atmosphere?

78% Nitrogen

21% Oxygen

1% Other gasses

Historically, fires ignited due to ______ ______, primarily ______ and ___________ _________

Abiotic Factors

Lightning

Spontaneous Combustion

Initial heat to start a fire is _____

Ignition

What is actually burning in a fire?

Flammable gases

Sustaining fire is dependent on what 3 factors?

Weather

Topography

Fuel

Landscape fire patterns are determined by what 3 factors?

Climate

Ignitions

Vegetation

What does a blue flame indicate?

Complete combustion

What does a yellow flame indicate?

Incomplete combustion

What are the 5 phases of combustion?

Preignition

Ignition

Flaming Combustion

Glowing Combustion

Extinction

What is preignition?

Fuels must be a certain temperature to ignite, this varies by fuel types

What are the 3 phases of preignition?

Dehydration

Volatilization

Pyrolysis

What is Dehydration? (in regards to preignition)

Fuels must be dry enough to ignite

What is volatilization?

Conversion of waxes/oils to vapor

What is pyrolysis?

Thermal degradation to volatile gases, semi-volatile tar, and solid char

What does white smoke indicate?

Water Vapor

Green fuels

What does black smoke indicate?

Volatile fire

Heavy fuels not fully consumed

Sometimes manmade materials

What does gray smoke indicate?

Fire winding down

Smoldering

What is required for ignition?

Initial heat

T/F: a spreading fire is a series of smaller ignitions

True (technically)

What does ignition temp vary by?

Fuel moisture

Fuel Type

Relative concentration of fuel and oxygen

What are the primary volatile compounds in wildland fires?

Terpenoids

What highly influences time to ignition?

Fuel moisture

What is flaming combustion?

The active flaming stage, where oils are volatized & burned

What is an example of a green fuel that can significantly contribute to flaming combustion?

Gallberry

Palmetto

Wax Myrtle

What is glowing combustion?

After volatile oils are consumed, solids begin to burn

What are the 2 primary soilids in wildland fuels?

Cellulose & lignin

What is the complete combustion formula for cellulose?

6CO2 + 6H2O + ignition heat → C6H12O6 + 6O2 + Heat

T/F: Fire often results in complete combustion

False (INcomplete combustion)

Why does fire often results in incomplete combustion?

Lignin & cellulose are not glucose

Secondary compounds do not have same ignition temp

What are some additional byproducts that are created by incomplete combustion?

Unburned hydrocarbons

Carbon monoxide

Particulates

Mineral (or ash) content

What emissions from prescribed fire are particularly dangerous to human health?

Carbon Monoxide (CO)

PM < 2.5

Where on the fire line poses the most risk for carbon monoxide poisoning? (According to Dr. Lane)

Idling on the UTV

What is smoldering?

A type of combustion that occurs at low temperatures, often with wet or subterranean fuels or following a surface fire

What is extinction? (In regards to fire, not the ESA)

The termination of combustion

What are several factors that extinction relies upon?

Fuel limitations

Insufficient Oxygen

Insufficient heat to sustain process

What is a head fire?

Fire burning with the wind

Why are head fires so volatile? (HINT: what are they doing to unburned fuels?)

Preheating

What is a backing fire?

Fire burning against the wind?

How do underground fires start?

Either through soils (peat) or with tree stumps

What can you do to extinguish underground fires?

Nothing

What is Heat? (not the 1995 Robert DeNiro movie)

Energy movement as a result of temperature differences

How is heat generated

By chemical processes

What are the 3 ways heat can be transferred?

Conduction

Convection

Radiation

What is conduction?

Movement from one part of fuel to another

What is convection?

Transfer of heat by movement of a gas or liquid

What is radiation?

Heat movement through waves traveling at the speed of light

What does heated air do?

Rises

T/F Conduction is important for upward movement of heat

False (downward movement)

T/F: Cellulose is a very poor conductor of heat

True

What commonly dehydrates and preheats fuels?

Radiation (usually from the sun)

What is residence time?

How long flaming front stays in one place

What are the four primary characteristics that describe fuels?

Fuel Type

Fuel Arrangement

Fuel Size & Moisture

Fuel Load & Duff Conditions

What is fuel type?

Refers to the different sizes of live or dead vegetation arranged on the ground

What are the 2 broad fuel types?

Light & Heavy

What are light fuels? (Fine Fuels)

Any fuel with a diameter </= 1”

T/F: Fine Fuels have a high surface area to volume ratio

True

A high surface area to volume ratio means that fine fuels have/are: (I hope i worded this good enough)

Quicker drying

Quicker dehydration during preignition

Lower ignition temperature

Easily extinguished after rapidly spreading fires with little residual smoke

Whats a factor that matters with light fuels? (HINT: see picture)

Compaction

What are heavy fuels?

Fuels >/= 1” Diameter

What is an issue that is caused by heavy fuels?

Smoldering

T/F: Cool season burns produce more smoke than warm season burns

False (flipped)

What does KBDI stand for?

Keetch-Byram Drought Index

Dead fuel moisture is assessed using ______

Timelag

How big is a 1 Hour fuel?

< 0.25” in diameter

How big is a 10 Hour fuel?

0.25-1” in diameter

How big is a 100-hour fuel?

1-3” in diameter

How big is a 1000 hour fuel?

3->8” in diameter

What has a huge effect on 1 hour fuel moisture?

Relative Humidity

If your RH is < _____ avoid burning

30%

RH is naturally at lowest between what hours?

1-3 pm

What is percent fuel moisture?

How much moisture fuels can hold

What is the recommended fuel moisture to avoid burning 100/1000 hr fuels?

17%

What is moisture of extinction?

Fuel moisture content at which a fire will not spread, spreads only sporadically, and in a non predictable manner

What is fuel arrangement?

How the fuels are arranged horizontally & vertically

2 main categories of horizontal fuel

Patchy

Continuous

What the minimum size for a fire break?

No smaller than 1 ½ x flame length; 3 ft min

What are the 4 main categories of vertical fuels?

Ground fuels

Surface fuels

Ladder fuels

Aerial or canopy fuels

What are ground fuels?

Below surface litter, includes duff, peat, roots, etc.

What are surface fuels?

All combustibles on or near the surface

What are Ladder fuels?

Create a continuity between surface and canopy, allowing fire to carry into tree crown relatively easily

What are Aerial or Canopy fuels?

Tree canopy, including branches, twigs, needles, etc.

What is fuel loading?

The quantity of fuels in an area, represented most commonly by tons/acre

What does Rough mean?

Years since last burn

You receive a call from John Landowner asking you to burn his stand. He says that it has a 5 year rough, what does that mean?

5 years since last burn

What 2 ways is fuel loading measured?

Direct measurement via sampling

Estimation via photo comparisons

Fuel loading & continuity can be directly measured using the _________ ________ method

Planar intercept

What is a major challenge you will encounter in roughs >5 years?

Duff

What is duff? (We didn’t go over the definition in class, but still good to know)

Decaying forest floor litter

Major challenges duff presents

Smoldering/smoke issues

Tree death if feeder roots get burned

What might a burn be considered if substantial duff is present?

Restoration or first entry

To avoid burning duff, 3 steps should be followed prior to a burn

Know the last day of rain

Know current drought conditions

Know current moisture level of duff in stand

T/F: after a hurricane, the KBDI will be around 800

False (800 is death valley dry)

What do restoration burns aim to remove?

½ - 1” of duff

_____ is the key factor for determining what will burn

Moisture

2 major drivers in wind

Temperature gradients between equator & poles

Earth’s spin

What is the Coriolis effect?

Wind travels east/west on the equator because it has to travel farther than the poles

T/F: North America is affected by Westerlies

True

Southeast weather is affected by the _____

ENSO = El Niño-Southern Oscillation Cycle