The Science of Wildfires

So, what is fire, exactly? What causes fires in the wild, and how do we put them out? SciShow answers your burning questions about the science of fire. (See what we did there?)

Hosted by: Michael Aranda
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[heatherheward]

As a fire educator at the University of Idaho I appreciated this positive shout out to fire. We need more things like this. My only complaint is that the image of a "dense" forest was of a bald cypress swamp that does not burn often anyway. With so many stock images of crowded pine stands I am not sure why that was used.

[RainAngel]

My uncle lives in a small town that recently burned down because of a wildfire. Only his house and a few commercial areas were spared. He saw it coming and started spraying the house down with his garden hose, just soaked everything. He lost the shed, but the house was barely singed.

[phrygianphreak]

I'm surprised they didn't mention the human adaptation to wildfires.
For example, the Native Americans would commonly practice slash-and-burn. Other cultures did this, but usually only to farmlands. Native Americans, however, noticed how fertile land was after a wildfire and began setting off huge wildfires every decade or so, usually when they noticed a dense layer of dead leaves on the ground that began to choke out the lower lying grass and flowers. Its interesting how we, at least in america, went from taking care of not enough wildfires to causing too many.

[springbok]

I’m here after a fairly fierce fire started on Table Mountain, Cape Town. I have not seen a fire move so quickly and intensely before inside a city. This is the first time that a fire moved around the mountain, gutting parts of one of Africa’s best universities (UCT) before moving into suburbs and setting trees and houses on fire. Fortunately the fire teams have brought it under control.

Thanks for this video, I know a little bit more about forest fires now.

[FirekillerDnB]

Glad to see my profession being highlighted on this video. I've got 10 years experience in many fuel types. from the northwest "rain forests" to the rocky mountains. even the swamps of the south. Different fuels cause different fire behavior.
I'm curious how you got that number that 95% of fires are human caused. that might have been true 30 years ago but i don't think that's the case anymore. I'd say 80% of the fires i've been on have been caused by lightening. But I work on a hand crew. we go where there are no roads to get into the fire. This number must count all the grass fires on the side of the road and stuff like that.

[cloverhighfive]

I remember when Michael was not sure he'd be good at this. Wow. Michael, you're good at this. Very happy you're an official co-host :D

[leoyan]

Great!!! I like SciShows narrated by Michael Aranda better than anyone else from SciShow.

[MoStLyaWaKE]

This video was shown in my fire fighting training course. I think I was the only guy there that had watched some of your videos beforehand.

[KingDecahedron]

Fire actually needs 4 things; heat. oxygen, fuel and Marshmallows !

[SmashtheCmachine]

I knew quite a bit about this subject, but leave it to Scishow to inform me of what I did not!

I knew about the cycle of fires involving the nutrients, and providing moisture/sunlight to new vegetation, and the three factors contributing to them, but about the "sticky-water", and the science of firefighting, I was pretty clueless.

[OurayTheOwl]

I literally hiked through a wildfire this past Tuesday on my weekly hike. It had mostly run its course with only small pockets of flames, but the fire still burned underground nearly melting my boots in certain areas and continued to smolder for days after my pass through. And yes, it was due to human neglect.

[CrownGamingAU]

Oh, okay. A wildfire is faster than me and it can follow me up and down hills. Anybody know any good deals on house-boats?

[Fionasichanie]

Most of the wildfires in California leave confusing aftermath photos such as trees burnt from the inside with leaves still intact yet cars nearby with melted out windows and aluminum!

[Irrazzo]

In one documentary, they said that grasses are younger plants in the evolutionary than trees, and appeared around 100 million years (or a bit more, I forgot). According to that documentary, much of the land was covered in forest. Some grasses evolved to burn lightly with high temperature which led to thousands of years of global and heavy wildfires. Grass was fighting the trees, claiming territory.

[erin]

I prefer Michael's delivery to Hank's. Hank speaks so quickly and drops consonants, particularly toward the end of sentences. Enunciate! 

[whereeveritgoes]

The last part of this video really amazes me. When you tell someone in your house that putting out wildfire too frequently could result in larger wildfire in the future, they would go, "Wut?" This video explains it well. Glad I didn't skip this!

[Spider-manPopsicle]

7:21 he really just predicted the possible fires in Australia

[Weendigo]

Hey guys! I'd just like to make a short distinction here: Volatile gases are not the same thing as smoke. All you guys are saying about the volatile gases emitted by hot wood and how they are expelled is completely true, but this is one important distinction to make.
What we "know as smoke" as you say, is simply an aerosol of liquid and solid particle, commonly soot, ash, various non-flammable or unignited liquids and so on, which rises off the wood because the gases and particles in the aerosol are hotter than surrounding air. It is of course true, though, that smoke does contain flammable vapours and gases.

However, it's important to know the difference, because dry wood starts emitting volatile gases at temperatures as low as 100 degrees Celsius, but doesn't ignite until temperatures ranging from 280 to 500 degrees Celsius, depending on the circumstances, such as if there is a flame involved or if it spontaneously combusts. Various online sources give different estimates, and every type of wood is different(pine with its high resin content, densely packed cork, etc). Otherwise, great episode, and I love the show! Keep up the good work. :)

[Mysteryskatin]

One of the coolest things about large fires is their ability to create their own weather systems. (Yeah, they actually *try* to teach us firefighters science, heh. We don't just hike and smack the ground with tools all the time.)
The smoke plume of large fires can produce thunderstorms, which ignite small fires in front of the head of the main fire via lightning. In an unstable atmosphere firewhirls can grow very large. In '14 there was a F1 scale tornado made out of fire in N. Cal that snapped Doug Fir like toothpicks.
It's also pretty hard for people to understand why we light the forest on fire to stop forest fires. We spend a lot of our time lighting shit on fire - it's like legal arson. Greatest job in the world. :P

[blackoak]

More in-depth than I expected, good job!