- [Narrator] On average, wildfires burn
up to five million acres of land
in the United States each year.
While they can start
naturally, wildfires are often
caused by humans with
devastating consequences.
Wildfires are large, uncontrolled infernos
that burn and quickly spread
through wild landscapes.
Types of wildfires may
include forest, brush,
and peatland fires, depending
on the landscapes affected.
Wildfires require three components,
known as the fire triangle.
A heat source, fuel, and oxygen.
Heat sources, such as the
sun, a hot bolt of lightning,
or a smoldering match
can supply enough heat
to spark a fire.
That spark then turns
into flames when fuel
or any flammable material is present.
Dry, dead grasses, leaves, and trees
are common fuels for wildfires,
but so are living vegetation,
called green fuels.
Pine trees and other evergreens contain
flammable oils that can burn
when exposed to a heat source.
As the fuel burns, the
resulting flames feed
and thrive off of oxygen.
When air movement or wind
occurs, not only is more oxygen
supplied to the fire, but
it may also help transport
and spread the flames.
Since wildfires occur
outdoors, they have a nearly
endless supply of oxygen
from our atmosphere to burn.
Many wildfires are the
result of natural causes.
A warmer climate and weather
patterns like El Nino
can create the hot, dry
conditions necessary
for fires to erupt.
However, about 90% of wildfires are caused
by human activity, such
as campfires that become
uncontrollable, improperly
handled cigarettes, or arson.
Although wildfires occur
worldwide, they are most common
in the Western United States.
There, high temperatures, drought,
and frequent lightning and
thunderstorms can create
the perfect setting for wildfires.
While they can be destructive,
and sometimes even deadly
for humans, wildfires do play
an important role in nature.
They can help a forest by
removing harmful insects
or diseased plants and they
can clear thick canopies
to help sunshine reach
seedlings on a forest floor.
By being aware of the conditions necessary
for wildfires to occur, they
can be managed and prevented,
thereby saving lives and making way
for the positive effects of wildfires.
(gentle music)
