Ambient Heat – Starting from the forest’s ambient temperature and raising as a fire moves approaches, and decreasing as the fire passes by or dies our for lack of fuel or oxygen.

Ambient Temperature- Temperature to which environment will cool based upon Newton’s Law of Cooling

Dry Fuel- Fuel classified as having a lower moisture content requiring a lower flash point than wet fuel.

Elevation Assumption- Changes in ground level affect fire because of differences in oxygen

Elliptical Fire Theory- Theory that fire will form a perfect ellipse under perfect burn conditions. This implies that to properly account for fire flow, the polar radii can be shortened and lengthened accounting to different variables’ effects on fire.

FARSITE- Forestry Service’s fire approximation program based on Huygen’s Principle.

Fire – The chemical reaction of fuel, ignition heat, and oxygen which generates additional heat burning fuel and oxygen. Fire is self-perpetuating as long as sufficient fuel and oxygen remain.

Fire Acceleration- As fire grows larger, it accelerates faster. The heat assumption may account for this phenomenon.

Fire Arcs- The collection extensions of the fire radii from a single point.

Fire Flow – The most commonly understood definition of a fire, defined as the actual, observable movement of a fire through a forest.

Fire Perimeter- Collection of fire arcs that, with fire perimeter reduction, form a perimeter around the fire.

Fire Perimeter Reduction- For better efficiency, unneeded fire arcs are deleted in the middle of the fire.

Fire Radii- Polar extensions from a central ignition point. For example, 3 units at 30 degrees. Fire radii are susceptible to changes in lengths based upon factors involved in fire flow.

Fourier’s Law of Conduction- Law to describe conduction. Heat flow through air can be considered conduction.

Fuel- Every patch has fuel with different moisture contents. These moisture contents are simplified into two types of fuels requiring different prerequisites to burn then.

Fuel Type – Different types of fuels where each contain its own heat generation factors, ignition point values, dry and wet fuel ratings, etcetera. Some examples include trees and shrubs.

Fuel Type Assumption- As fire flows over different types of ground coverage, it will spread faster or slower depending upon the fuel type’s atomic structure and typical surface area.

Heat Flow – The transfer of heat in a forest as a fire moves, as well as, during everyday circumstances. Generally connected to fire flow because of the natural properties of fire which gives off heat as a byproduct, but can also be associated with ambient warming and cooling with the time of day.

Heat Assumption- Different amounts of heat cause fire to spread differentially. The hotter it is, the faster the fire flow.

Huygen’s Principle- FARSITE equation that uses wind and elevation to determine an ellipse that the fire will follow.

Ignition Point – Minimum temperature at which a fuel will ignite and become self sustaining based on fuel type and environmental factors.

Moisture Assumption- More moisture will slow fire spread.

Mini-Patches- Patches divided into 100 equal parts to better keep track of certain aspects in the program.

Newton’s Law of Cooling- Variable equation that accounts for cooling of patches during radiation, convection, and conduction.

Patches- Division of fuel type exactness and area. One patch is approximately 1 sq meter.

Piloted Flash Point/ Instantaneous – Point at which patch will combust whether or not fire is present.

Rapid Oxidization- The scientific term for the chemical reaction of fire. Rapidly taking of the oxygen in the fuel.

Spot Fires- A term for sparks that fly into the air and create fires in new places down wind.

Spread Rate- The rate at which fire can spread across the ground. Influenced by many environmental factors, heat, wind, and other factors.

Stefan-Boltzmann Law of Radiation- Law to give the amount of radiation emitted from an object based upon its emmisivity and temperature.
Unpiloted Flash Point/ Basic – Temperature which is required to burn a certain fuel.

Virtual Forest- Collection of patches that make up the forest environment.
Wet Fuel- Fuel classified as having a higher moisture content requiring a higher flash point than dry fuel .

Wind Assumption- Wind’s affect upon fire can be described as a vector of wind speed and fire spread.

Wind Vectoring- The process of correcting fire flow for wind.