Glossary

Term	Definition
Alignment of Forces	There are three primary forces causing variations in fire behavior. They are wind, slope, and preheat. When these forces align, the fire is going to be at its maximum intensity. When these forces are not in alignment, the intensity is lower than the maximum. This is the alignment of forces concept.
Dominant Force	The dominant force is one of the primary forces slope, wind, or preheat. Any one of these forces can dominate the fire behavior. This is important because if the dominant force changes, the character of the fire will change also. For instance, a wind driven fire will, in effect, flatten the effects of terrain and reduce fuel temperature and moisture variations. When this fire burns to a location that is sheltered from wind, a new dominant force will drive the fire.
Fire Behavior	Measurable attributes of a fire quantified by flame length, rate of spread, and fireline intensity.
Fire Signature	A fire signature is the observed fire behavior within the current alignment of forces. The fire signature is the ground truth. It is how the fire will behave in similar conditions.
Trigger Point	A trigger point is a place on the terrain where a change in the alignment of forces will change the fire behavior, creating either an opportunity or a danger. Trigger points are a time and/or place the tactic or placement of resources needs to be changed to assure firefighter safety. There are two crucial trigger points to establish -- one is where the fire will change; the other is when and where the fire triggers a decision to change tactics.