What characterizes a flare up?

• A. A long, steady increase in fire intensity
• B. A temporary lull in spread
• C. A gradual cooling of fuels
• D. A sudden but short-lived rise in rate of spread or fire intensity usually attributed to wind, fuel, or topographical changes; flaring proceeds a blowup.

Answer: (D)

A flare up is a sudden but short-lived surge in fire intensity or rate of spread caused by a brief change in conditions—often a gust of wind, the arrival of new fuel, or a terrain feature that creates a momentary boost in heat, oxygen, or flame contact. This quick spike can precede a blowup, making it a warning sign that fire behavior is ramping up rapidly.

Why this fits best: it captures both the abrupt nature and the typically temporary duration of the event, plus the common causes (wind, fuel, topography) and the sequence that flares can lead to a blowup. The other options describe things that don’t match a flare up: a long, steady increase implies sustained growth rather than a brief spike; a temporary lull is the opposite of a surge; and a gradual cooling of fuels would reduce activity rather than cause a sudden rise.