Term
|
Definition
| basic principles and mechanisms of the combustion process |
|
|
Term
|
Definition
|
|
Term
| photosynthesis (chemical equation) |
|
Definition
| CO2 + H20 + solar energy -> (C6H10O5)n + O |
|
|
Term
| combustion (chemical equation) |
|
Definition
| (C6H10O5)n + O + ignition temperature -> CO2 + H2O + heat |
|
|
Term
|
Definition
-thermal degradation of fuel
-chemical decomposition through application of heat
-pyrolysis="heat divided" |
|
|
Term
|
Definition
-endothermic reactions, dehydrate the fuel, fuel brought to ignition/kindling temp.
-volatiles released |
|
|
Term
|
Definition
-exothermic reaction, processes fuel based on combustion chemical equation
-may or may not involve flame |
|
|
Term
|
Definition
| point of transition between preignition and combustion, the temperature at which a pilot source of heat is no longer needed |
|
|
Term
|
Definition
-termination of combustion
-occurs when not enough heat is available to sustain the combustion process w/o pilot heat source |
|
|
Term
| fire fundamentals triangle |
|
Definition
|
|
Term
|
Definition
-principle constituent of all higher plants
-condensation polymer of the hexose sugar D-glucose
-a major contributor of combustible volatiles |
|
|
Term
|
Definition
-gives wood it's stiffness
-aromatic polymer, 4+ major phenylpropane monomers per molecule
-dead fuels have progressively higher lignin contents as they age
-when heated, produces carbaceous char, which is required for glowing combustion |
|
|
Term
|
Definition
- a class of compounds consisting of: aliphatic and aromatic hydrocarbons, alcohols, aldehydes, gums, sugars
-seasonal fluxtuations in content of volatiles
-flammable |
|
|
Term
|
Definition
| a function of the kinetic energy of the motion of a substance's molecules |
|
|
Term
|
Definition
-thermal energy, the energy of molecular motion
-essential for a wildland fire to start and continue to burn
-energy in transit as the result of a temperature difference |
|
|
Term
|
Definition
| -total heat required to raise the temperature of a unit mass of a fuel to the ignition temperature |
|
|
Term
|
Definition
-energy that maintains the chain reaction of combustion
- aka heat value/heat content
-total amount of heat released when a unit quantity of a fuel is oxidized completely |
|
|
Term
|
Definition
-aka heat release/heat intensity
-amount of heat produced per unit of fuel consumed per unit of time or energy per unit area
-not a property of the fuel, but of the energy transfer process |
|
|
Term
|
Definition
-the process or mechanism by which the energy is moved from one source to another
-occurs whenever there is a temperature difference in a medium or between media
-3 basic mechanisms: radiation, convection, conduction |
|
|
Term
|
Definition
-the transfer of heat by molecular activity from one part of a substance to another or between substances in contact w/o appreciable movement of the substance as a whole
-varying ability of different soils and of water to absorb and conduct heat has a profound effect on local and global climate and weather
-heat flows from a region of high temps. to one of low temps. |
|
|
Term
|
Definition
-the transfer of heat by the movement of a gas or liquid
-primarily responsible for preheating the higher shrub layers and crown canopy
-to or from a solid involving movement of a surrounding fluid |
|
|
Term
|
Definition
-radiant energy
-electromagnetic waves travel @ speed of light |
|
|
Term
|
Definition
| removes volatiles by the distillation of water and extractives |
|
|
Term
|
Definition
| organic forest horizons that accumulate over mineral soil |
|
|
Term
|
Definition
-ratio of the actual carbon contained in the emissions of carbon dioxide compared to that theoretically possible if all of the carbon were released as carbon dioxide
-the remainder comes out as particulates (tar, ash), CO, CH4, NMHC |
|
|
Term
|
Definition
| -all vegetative and animal material including the roots deep in the soil |
|
|
Term
|
Definition
-plant material above mineral soil
-considered "total fuel" |
|
|
Term
|
Definition
-material on a site that might burn in a most intense fire
-value < total fuel |
|
|
Term
|
Definition
fuel that is available for cobustion in a given fire
-depends on environmental conditions |
|
|
Term
|
Definition
| -description of fuel itself |
|
|
Term
|
Definition
-dependent on changing environmental conditions
-related to moisture content |
|
|
Term
|
Definition
-both human and natural
-can impact fuel state |
|
|
Term
|
Definition
-impact fuel state
-dirunal changes, synoptic weather changes, seasonal change
-fire weather is a dominant factor in determining the fire potential for a day |
|
|
Term
| biological/physiological cycles |
|
Definition
-greenup/curing, leaf drop, decay, plan succession
-impacts fuel types and states |
|
|
Term
|
Definition
| -determined by changes throughout the year, in both weather and fuel |
|
|
Term
|
Definition
-determined by multi-year weather patterns
-important to fire planning, preparedness, and prescribed fire
-largely determines the amount and kind of vegetation in an area, sets the pattern for variation |
|
|
Term
|
Definition
-lowest layer of the atmosphere
-temp generally decreases with altitude
-the region of changeable weather
-contains 3/4 of earth's atmosphere by weight
[image] |
|
|
Term
| standard atmospheric pressure |
|
Definition
-normal pressure exerted by the atmosphere at sea level
-total weight of a 1-inch square of air from sea level to the top of the atmosphere averages 14.7lb or 29.32 inches of mercury |
|
|
Term
|
Definition
| ability of the atmosphere to retain heat through absorption by water vapor and other gases |
|
|
Term
|
Definition
| temperature to which air must be cooled to reach its saturation point at constant pressure |
|
|
Term
|
Definition
| ratio of the amount of moisture in the air to the amount that the air could hold at the same temperature if it were saturated |
|
|
Term
|
Definition
| lowest temperature to which the air can be cooled by evaporating water into it at constant pressure |
|
|
Term
|
Definition
| -resistance of the atmosphere to vertical motion |
|
|
Term
|
Definition
| change in temperature with altitude |
|
|
Term
|
Definition
-atmospheric movement occurs without heat or mass added into the system
-lapse rate continuously changes as air circulates within the atmosphere (warmed by compression, cooled by expansion) |
|
|
Term
|
Definition
| 5.5 degrees/1000 feet, meaning a bubble/layer of dry air will always have a temp decrease of 5.5 degrees/1000 feet when lifted due to decreasing pressure and expansion. Opposite if downward. |
|
|
Term
| moist adiabatic lapse rate |
|
Definition
-3 degrees F/1000 feet, meaning a bubble/layer of wet air will always have a temp decrease of 3 degrees F/1000 feet when lifted due to decreasing pressure and expansion. Opposite if downward.
-rises and cools @ dry rate until it reaches its saturation point
-when air rises, it cools with a corresponding rise in relative humidity |
|
|
Term
|
Definition
-encourages the vertical movement of air and tends to increase fire activity
-if fuel, topography, other weather elements are held constant, unstable air will enhance the vertical development (shape), rapid expansion (growth), and increased proportions (size) of smoke columns, as compared to stable conditions |
|
|
Term
|
Definition
-if lapse rate is > 5.5 F/1000 ft
-discourages the vertical movement of air
-usually decreases or holds down fire activity |
|
|
Term
|
Definition
| -a layer of very stable air where the temperature increases with altitude |
|
|
Term
| radiation/nighttime inversion |
|
Definition
-most common type inversion
-form when air is cooled at night by contact with the earth's surface
-cool, heavier air below warmer air |
|
|
Term
|
Definition
-cool, moist air from the ocean spreads over low-lying land
-topped w/ much warmer, drier, relatively unstable air |
|
|
Term
|
Definition
-associated w/ high pressure systems in upper atmosphere
-sinking air warms and dries as it descends to lower altitudes
-results in layer of warm/dry air that becomes progressively warmer/drier as it drops closer to the surface
-slow process occurs over days |
|
|
Term
|
Definition
-air heated strongly near the ground, then lifts
-cools as forced aloft |
|
|
Term
|
Definition
-mass of moving air is forced to rise because of presence of a slope
-in mountainous terrain |
|
|
Term
|
Definition
| -moving, cooler air mass pushes its way under and lifts a warmer air mass |
|
|
Term
|
Definition
-excess air forced upward because more air is moving into an area that is moving out
-can occur independently, or be present during frontal, orographic or thermal lifting |
|
|
Term
| cumulus stage of thunderstorm |
|
Definition
-rising column of moist air develops a cumulus cloud that grows vertically
-clouds have strong indrafts into the base of the cloud that may increase surface winds
-updrafts causes wind direction to change because air moves towards cloud |
|
|
Term
| mature stage of thunderstorm |
|
Definition
-begins when rain/virga starts to fall
-downdraft in rain part of cloud, updraft remains in rest
-anvil-shaped layer of ice crystals forms, and lightning happens (cumulonimbus cloud)
-downdrafts that reach the ground result in cool, gusty surface winds |
|
|
Term
| dissipating stage of thunderstorm |
|
Definition
-entire thunderstorm becomes and area of downdrafts
-gradually, downdraft weakens, rain subsides, clouds dissipate |
|
|
Term
|
Definition
| horizontal movement of air relative to earth's surface |
|
|
Term
|
Definition
| winds produced because air moves from high pressure to low pressure areas |
|
|
Term
|
Definition
| winds that blow in the upper atmosphere, unaffected by friction from terrain or other surface characteristics |
|
|
Term
|
Definition
| winds that occur at the top of the frictional disturbance layer, which is dependent on surface characteristics |
|
|
Term
|
Definition
| pressure differences across landscape |
|
|
Term
|
Definition
| in N. hemisphere, air is deflected to the right as earth rotates on its axis, causing constant motion of air (wind) |
|
|
Term
|
Definition
the boundary between two air masses of different temperatures and other characteristics
-generally, air masses are stable ahead of a front, unstable near the front, and stable behind the front |
|
|
Term
|
Definition
| -smaller-scale winds caused by local temperature differences |
|
|
Term
|
Definition
flow of air inland from over the water, forcing the warm air over the land to rise and cool adiabatically
-completes circulation cell in absence of strong general winds |
|
|
Term
|
Definition
reverse of daytime sea breeze
-land surfaces cool more quickly than water at night, causing a difference in air pressure. |
|
|
Term
|
Definition
convective type of wind
-local diurnal winds present on all sloping surfaces
-upslope during the day as the result of surface heating
-downslope at night due to surface cooling |
|
|
Term
|
Definition
-warm air sheath next to a slope serves as a natural chimney and provides a path of least resistance for the upward flow of warm air
-layer of warm air is turbulent and bouyant, increasing in depth as it progresses up slope
-daytime process, reverses @ night |
|
|
Term
|
Definition
-shallow movement of cooled air sliding down a slope
-principal force is gravity
-continue through night until morning |
|
|
Term
|
Definition
-mechanical way that topography affects wind
-large drainage in a plateau region or any area allowing a general wind flow diverts some of the wind flow and sends it in a direction parallel to the drainage |
|
|
Term
| venturi efffect on wind based on topography |
|
Definition
-mechanical way that topography affects wind
-air pouring through a pass, saddle, or gorge speeds up |
|
|
Term
|
Definition
-waves imparted to general wind flow due to passage of wind across mountains
-most likely when air mass is stable aloft |
|
|
Term
| thermal turbulence (wind) |
|
Definition
-caused by differential surface heating
-can have large effect on low-level wind
-diff. land surfaces absorb, reflect, and radiate varying amounts of heat
-often makes winds gusty and erratic |
|
|
Term
|
Definition
-special case of general winds
-occur as heavy, stable air pushes across a mountain range and then descends the slopes on the leeward side, becoming warmer and drier due to compression
-tend to be stronger at night because they combine with downcanyon winds |
|
|
Term
|
Definition
| a general term referring to the recurrence of fire in a given area over time |
|
|
Term
|
Definition
(aka fire occurrence, fire incidence)
a single fire or series of fires within an area at a particular time |
|
|
Term
|
Definition
(aka fire-free interval, fire-return interval)
the number of years between two successive fire events in a given area |
|
|
Term
| mean fire return interval |
|
Definition
(aka mean fire interval) arithmetic average of all fire intervals in a given area over a given time period
-typically applied in fire regimes of low to moderate severity, using data from multiple fires in the same stand |
|
|
Term
|
Definition
(aka natural fire rotation) the length of time necessary for an area equal in size to the study area to burn
-fire regimes of moderate to high severity |
|
|
Term
|
Definition
the average stand age of a forest whose age distribution fits a mathematical distribution (negative exponential or Weibull)
-fire regimes of moderate to high severity |
|
|
Term
| point frequency (of fire occurrence) |
|
Definition
the mean fire-return interval at a single point on the landscape
-assumes fires will burn across this point at the mean frequency, usually with considerable variation around the mean
-ideally represents data from single tree, but more realistically, represents data from a group of nearby trees (once data sample gets bigger, it becomes an area frequency) |
|
|
Term
| area frequency (of fire occurrence) |
|
Definition
mean fire-return interval for a unit area of landscape
-commonly used in fire regimes where the only botanical evidence in most stands is of the last fire, so that evidence must be compiled from many stands across the landscape
-stand ages are a common data source |
|
|
Term
|
Definition
(NFR): the average number of years required in nature to burn over and reproduce an area equal to the total area under consideration
NFR (yr) = Total Time Period
Proportion of area burned in period |
|
|
Term
|
Definition
early ecologist who felt that plant communities move through a directional, cumulative, predictable, nonrandom change in species composition over time, ultimately leading to to a steady-state or "climax" community where further changes were inconsequential
-he felt disturbance, like fire, was external to the succession process and disrupted an equilibrium |
|
|
Term
| Fire regime: tall grass prairie |
|
Definition
-principally shaped by fire
-if burning suppressed, this regime succeeds to shrubs and trees
-impacts this ecosystem by 1)altering soil pH and 2) eliminating weeds
-annuals proliferate briefly after a burn, perennials persist throughout and are invigorated by fire's consuming of accumulated litter |
|
|
Term
|
Definition
-chamise a primary component, which changes physiologically after ~20yrs to become more flammable
-wildfire here difficult to control due to lots of VOCs in plants
-vigorous regrowth after fire |
|
|
Term
| Fire regime: ponderosa pine |
|
Definition
-adapted well to frequent, low-intensity surface fires
-trees develop a thick bark after ~5yrs of age that protects from low-intensity fire
-broadcast underburning a common management strategy |
|
|
Term
|
Definition
-large fires can occur any time within the life-history of dominant species
-main tree species plays multiple successional roles
-dominant tree species grows large, lives long and experiences infrequent, high-intensity crown fires |
|
|
Term
| Fire regime: loblolly and shortleaf pine |
|
Definition
-largest timber group in SE US
-most knowledge based on old field abandonment successions
-surviving seedlings develop resistance to burning and are subsequently favored by frequent surface fires
-if no fire for ~25 years, succession gives way to hardwoods because pine duff covered mineral soil which is best for pine germination |
|
|
Term
| Fire regime: lodgepole pine |
|
Definition
-principle species has serotinous cones, therefore post-fire regeneration is very successful
-high intensity crown fires every 200-300 years |
|
|
Term
|
Definition
places with natural boundary against fire
-provide good case study of fire regime sans human influence, or at least pre-management regimes |
|
|
Term
|
Definition
| type of fire that burns subsurface fuels within the duff layer; smolders |
|
|
Term
|
Definition
| type of fire that spreads by flaming combustion through fuels @ or near the ground surface |
|
|
Term
|
Definition
| type of fire that burns into and through the tree canopy |
|
|
Term
|
Definition
| when a fire spreads rapidly |
|
|
Term
|
Definition
| when a fire spreads slowly with low flames |
|
|
Term
|
Definition
| when a fire has no flame and is barely spreading |
|
|
Term
|
Definition
| when a fire produces sparks or embers that are carried beyond the active fire |
|
|
Term
|
Definition
| fires that are caused by new ignition from spotting |
|
|
Term
|
Definition
| when a fire moves from the surface to the crowns of individual trees |
|
|
Term
|
Definition
| when a fire moves from tree to tree independent of a surface fire |
|
|
Term
|
Definition
| when a fire suddenly accelerates in spread rate or intensity for a short duration in part of the fire zone |
|
|
Term
|
Definition
| when a fire experiences a dramatic change in the behavior of the entire fire, transition to "severe" fire |
|
|
Term
| fire environment triangle |
|
Definition
|
|
