The following three descriptors are used to characterize flaming combustion: 1) Flame height is the vertical distance from the base to the tip of the flames. 2) Flame length is the actual length of the flames from the tip to the midpoint of the flame footprint. Under no-wind conditions on flat ground, flame length equals flame height. Otherwise flame length will exceed flame height regardless of whether a fire is backing or heading. 3) Flame zone depth is the distance from the leading edge to the trailing edge of the flaming front measured at the base of the flames.