What is the difference between a head fire and a backing fire?

What is the difference between a head fire and a backing fire?

• A. A head fire moves downhill, while a backing fire moves uphill.
• B. A head fire moves with the wind and uphill, spreading rapidly.
• C. They are the same; no difference.
• D. Head and backing fires describe the same pattern.

Answer: (C)

The key idea is how wind and slope shape the two edges of a fire. The head fire is the leading edge that advances fastest, driven by the wind and typically moving uphill, because flames and heat preheat fuels upslope and the wind pushes the flames into unburned fuel. The backing fire is the opposite edge that moves against the wind and tends to go downhill, spreading more slowly and with lower intensity. So they are not the same fire pattern; they behave differently because wind direction and slope affect spread rate and flame behavior at each edge.

The key idea is how wind and slope shape the two edges of a fire. The head fire is the leading edge that advances fastest, driven by the wind and typically moving uphill, because flames and heat preheat fuels upslope and the wind pushes the flames into unburned fuel. The backing fire is the opposite edge that moves against the wind and tends to go downhill, spreading more slowly and with lower intensity. So they are not the same fire pattern; they behave differently because wind direction and slope affect spread rate and flame behavior at each edge.