In fire behavior taxonomy, what defines the difference between vertical and horizontal vortices?

The distinction between vertical and horizontal vortices in fire behavior taxonomy is defined by the axis of rotation. Vertical vortices rotate around a vertical axis, which can contribute to fire intensity and spread by influencing the upward movement of fire, heat, and smoke. This type of vortex typically occurs in the presence of a strong thermal updraft, which might push fire behavior to more extreme levels, especially in hot, dry conditions.

On the other hand, horizontal vortices rotate around a horizontal axis. They are often associated with wind and can contribute to changes in the direction of fire spread. Horizontal vortices can create erratic fire behavior, as they might push hot gases and embers across a fire line or cause flame angles to shift unexpectedly.

The other factors, such as wind speed, type of vegetation, and fire size, may influence fire behavior and the development of vortices but do not define the difference between vertical and horizontal vortices themselves. Understanding the axis of rotation is critical to predicting how these vortices will affect fire dynamics, thus providing essential knowledge for managing fire situations effectively.