What characteristic feature indicates that a fire is moving quickly?

A characteristic feature that indicates a fire is moving quickly is large alligatoring. This phenomenon occurs when there is rapid and intense heat, which creates deep, pronounced patterns in the charred surfaces of wood. The appearance resembles the scales of an alligator, and this effect is usually associated with flames consuming the material at a fast rate due to an abundant supply of fuel and oxygen.

When a fire spreads quickly, it generates significant heat, leading to more extreme degradation of the exposed surfaces. In contrast, even charring would suggest a more controlled or slower burn, while low smoke production might indicate incomplete combustion or a lack of available fuel, both of which are not indicative of rapid fire spread. Similarly, a minimal heat signature would suggest that the fire is not strong or active, further ruling it out as a characteristic of a quickly moving fire. Therefore, large alligatoring effectively serves as a crucial indicator of a fast-moving fire due to the intense burning conditions that facilitate such a pattern.