Wildfires

1. Whether lightning or humans start more wildfires

About 85% of wildfires are started by humans, while the rest are started by lightning.
However, lightning-caused fires burn more total acreage.
This is because they occur in remote areas, go unnoticed longer, and are harder to fight.

2. Factors that strongly influence wildfire potential

Wildfire potential depends on vegetation type, topography, and weather.
Dry fuels burn more easily, fires burn uphill faster, and hot, dry, windy conditions increase spread.
Strong winds and steep slopes greatly accelerate fire growth.

3. What surface fires and crown fires are

Surface fires burn grasses, pine needles, shrubs, and low vegetation and can spread quickly.
Crown fires burn through tree canopies and are the hottest, fastest, and most dangerous fires.
Crown fires are often driven by strong winds and steep terrain.

4. The three stages of a wildfire

The three stages are preignition, combustion, and smoldering/extinction.
Preignition dries fuels, combustion releases heat through chemical reactions, and smoldering burns slowly under ash.
These stages explain how fires start, grow, and eventually die out.

5. Largest wildfire in U.S. history

The Great Fire of 1910 was the largest wildfire in U.S. history.
It burned 3 million acres in two days across the Northwest.
It killed 87 people, including 78 firefighters.

6. Original and current U.S. Forest Service fire policies

After 1910, the Forest Service adopted a policy of aggressively suppressing all wildfires.
This led to fuel buildup and larger, more intense fires.
In 1972, the policy shifted to fire mitigation and management, allowing some fires to burn naturally.

7. Benefits of forest and grassland wildfires

Wildfires reduce fuel buildup and prevent catastrophic fires.
They improve ecosystem health and wildlife habitat.
Some plants, like lodgepole pines, require fire for seed germination.

8. Difference between a fire weather watch and warning

A fire weather watch means dangerous fire conditions are possible in 12–72 hours.
A fire weather warning means fires are occurring or likely within 24 hours.
Warnings indicate more immediate danger.

9. Dangers of firebrands and wildfire safety practices

Burning embers (firebrands) are the main cause of homes igniting in subdivisions.
They can travel long distances on strong winds and ignite flammable roofs.
Creating defensible space and evacuating early are key safety practices.

10. Purpose of a fireline and a backburn

A fireline removes vegetation down to bare soil to stop surface fires.
A backburn removes fuel ahead of an advancing fire.
Backburns are always set in conjunction with an existing fireline.

11. Why fire retardants are colored red

Fire retardants are colored red so firefighters can see where drops have been made.
This helps guide firefighting strategy and avoid duplicate drops.

12. Advantage of helitankers over air tankers

Helitankers allow more precise water or retardant drops.
They can refill from small water sources, including swimming pools.
Some carry water cannons, like fire trucks.

13. Main function of a smoke jumper

Smoke jumpers are deployed when fires are too remote for hotshot crews.
They perform indirect attacks, constructing firelines and slowing spread.
They are not dropped directly into fires.

14. What fire shelters are designed to do (and not do)

Fire shelters are a last-resort safety device that reflect heat and trap breathable air.
They are not designed for direct or sustained flame contact.
Firefighters must clear the area before deployment.

15. Factors contributing to the Granite Mountain Hotshots’ deaths

A sudden downdraft changed the fire’s direction.
The crew left a burned safety zone and did not reach the Boulder Springs Ranch.
The fire was too intense for their shelters, and their location was not known to air crews.