▶️ The Science of Wildfires

By SCOTT ELNES
CENTRAL OREGON DAILY NEWS METEOROLOGIST

It can spread up to a football field per second, and unlike humans, it actually runs faster uphill.

I am of course talking about wildfires. And when it comes to wildfires, just remember the number three.

Fire needs three things to start: Oxygen, Heat and Fuel.

Fire needs three things to spread: Fuels, weather and one other major factor, topography. In fact, according to the Australian Academy Of Sciences, fire doubles its speed for every 10 degrees of inclination.

When it comes to wildfires, weather is a major player that requires three things as well: Temperature, wind and moisture.

So let’s talk about fuels.

When wood gets to 572 degrees Fahrenheit or 300 degrees celsius, it reaches its flashpoint and releases flammable gases that, with spark and oxygen, create fire.

Wood from trees and brush along with dried leaves and plants create the fuel for fire. And the hotter it’s been, the more that fuel is dry and hot, bringing it ever closer to that flashpoint.

Once a fire has started, those fuels, along with how dry the air is, how steep it is, the amount of oxygen the wind is bringing and a hundred other factors can make a fire burn out of control faster than a human can run.

And to make matters worse, while lightning from a thunderstorm can start a wildfire, the smoke and rising hot air from a fire can actually create its own wind, and even a cloud called a pyrocumulonimbus cloud, that can actually create more lightning and start more fires.

For much of the 20th century, we believed that the best way to fight fire was to completely put them out. With more fuel and bigger fires, federal agencies have changed their approach letting some fires burn naturally.

But if a fire is threatening something important, we still race to put it out.

Believe it nor not, our planet actually depends on wildfires. Lodgepole pines, a common tree in Central Oregon, literally cannot reproduce until the heat of fire melts the resin on its cones and releases its seeds.

If we had no fires, these trees would die out.

By far, the biggest source of wildfires is humans.

But in an interesting twist, it is the fires created by Mother Nature that often become the largest. As they may go unnoticed, take longer to get to and offer more steep terrain to expand into.

So finding the balance of a good thing, and too much of a good thing is relevant now, more than ever.

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