n. Flame length is the distance from the ground at the leading edge of the flame to tip of the flame.
Flame length is referenced to the leading edge mainly because it then follows the streamlines in the flame. It has also been defined alternatively as the cord length from the tip of the flame to a point along the base of the flame midway between the leading and trailing edge. The former is the preferred definition.
Regardless of which definition is followed, it is critical to specify which definition is being used in relation to data that have been collected; likewise, it is also critical to verify which definition is being used in relation to data received from others. See Anderson and others (2006) for further discussion.