What stage of fire development is characterized by heat release and expansion?

The growth stage of fire development is characterized by significant heat release and the expansion of flames. During this phase, the fire begins to spread more rapidly due to the increased availability of fuel as materials within the environment ignite. The temperature rises, and the fire transitions from being confined to its ignition source to a wider area, intensifying its growth.

As the fire continues to develop during this stage, it consumes combustible materials, producing more smoke and flames, leading to further ignition of surrounding fuels. This behavior is critical for firefighters to understand, as it highlights moments when the fire can quickly become more dangerous and uncontrollable.

In contrast, the initial stage involves the first few moments after ignition, where heat release is minimal and the fire is still localized. The fully developed stage indicates that the fire has reached its peak intensity and is burning efficiently, while the decay stage represents a decline in heat and flame as fuels are exhausted and the fire begins to diminish. Recognizing these stages helps responders formulate appropriate strategies for intervention and control.