What are the natural causes of wildfires, how do wildfires start, are they preventable?

Bless the fire fighters for the "we can beat this" attitude, it takes courage
few of us understand. 

I have just discovered that the wild fire burning today out of control in the Columbia River Gorge was started by 15 year old back packers tossing fire crackers into the canyon.
  Montana is fighting a massive wildfire right now (September 4, 2017) the last I heard it was burning an area of about 8,000 acres. Los Angelo's fighting the largest fire that area has had in written history. British Columbia has just gotten a massive wild fire contained. It has gotten me to thinking about how wild fires start and what are the natural causes of wildfires:
  1) Natural causes of wildfires: Some wild fires do start naturally, generally ignited by intense sunlight, lightning strikes or lava.
  Lightning has two parts, leaders and strokes, the leader comes from the cloud and is sent to the ground, we cannot see the leader. The return is the visible flash, that jagged line of light (actually electricity) created by a series of "strokes" that are responsible for that bright flash we see. Cold and hot lightning, Cold is the return stroke with a very high electrical current lasting a short time. Hot lightning has less voltage, lasting for a long time span, the fires are generally caused by these unusually long lasting strokes or "lightning bolts". The reason the Hot Lightning is a more common cause of wild fires than is Cold Lightning is that the hot has a continuing level of current, the flow of electricity continues over a long period of time creating more heat. Cold lightning is a rapid flash with a loud thunder clap, very short duration incapable of generating enough heat to start a fire. Lightning is one of the most destructive forces on our planet causing more than 5 billion dollars in damages every year in the United States alone, it is also the cause of more deaths than hurricanes.

The big bolt is most likely a "hot" strike, the smaller ones are "cold" strikes,
a hot strike must have hit where the fire is starting in the left center lower. 

There is consistently 100,000 (more or less) lightning strikes on earth every day, the randomness of the occurrences makes scientific study very difficult, and explains why so little is known about the phenomenon. All of our home appliances have circuit breakers that "trip" well below 100 amps. Industrial plants have a circuit breaker controlling the entire plant that will trip at 2 amps, it's called a "man saver", it protects the people working on the electrical system in the control room where the many circuit breakers reside. In contrast, it's not unusual for a lightning bolt to contain 20,000-30,000 amps of current, that is a lot of current and makes it deadly when it goes to ground through a living body. The temperature of lightning is about twice the temperature of the Sun, the lightning is as high as 17,000 degrees Fahrenheit, no wonder it can start a fire in dry brush. Such was the beginning on July 23, 2012, of the "Lava Fire" started in the State of Oregon on rangeland. Burning over 21,000 acres, in the northern "Lake County" on Bureau of Land Management which included a large study area, it burned for over 3 weeks and demanded the attention of 275 personnel, One of the common natural causes of wildfires Lava, however, this one was called the "Lava fire" and not caused by it.
  2)  How do brush fires start? Volcano's start some, in the form of hot lava, red hot rocks and boiling ash being slung all over the country side. March 15, 2011, a fire was started by a lava vent, the Kamoamoa Fissure Eruption which occurred in Hawaii amongst a heavily forested area setting the vegetation on fire, destroying more than 75 acres. There are not a lot of wild fires started by Lava, The same is true of Land slides:
  3) Another natural cause of wild fires is rock slides, in mountainous areas rock slides are common, many occur during heavy periods of rain rendering them mute in so far as being able to create a spark. When the boulders and rocks tumble they strike against each other causing sparks, a lot of sparks are created in one landslide, it only takes one to ignite bone dry vegetation.

Sparking rocks when they hit against one another, is the cause of
many wild fires.

  4)  Spontaneous combustion, compacted organic material, piles of debris or piles of naturally occurring wood shavings from various bugs and animals digging and feeding in a log. I have witnessed many cases of spontaneous combustion, however, everyone was caused by the negligence of people. Which brings us to the biggest cause of wildfires, us, humans:
  5)  Human beings, you and I are the most common causes of wild fires, I feel we all know that. Cigarettes tossed out windows is a common cause, apparently, we think since it's a small ember it's pretty harmless. Camp fires, boy scouts taught us to pour water on a camp fire then stir it, pour more water and stir some more, make sure it is out. Lawn mowers, gasoline powered tools, and vehicles, the hot exhaust pipes and gases take their toll, Catalytic converters in a failure mode begin to get so hot they glow red. When we pull off the road when a Catalytic converter is failing will surely cause a fire, then the vehicle is involved as well. Sparks from a wood burning stove cause some wild fires, home fires are sometimes one of the causes of forest fires. Controlled burns will sometimes go rogue, set as back fires or burning of brush and debris fires sometimes go wildly out of control.
  6)  Forest fire causes and effects: Volcano's, rock slides, lightning and spontaneous combustion amount to 45% of the causes of wild fires. People cause the remaining 55%, it sounds about right to me. One of the fires around where I live was recently started by a guy shooting a 22 rifle at cans, he did it all the time with no problem, it only took one round and one second to start a fire. I was inside a friends garage when a spontaneous combustion fire started just outside on the side of the garage. The guy that lived there had at one time placed a pan of used motor oil next to the garage for a few minutes. The few minutes grew into a much longer term, the container leaked and the oil spread out on the ground and surrounding weeds. It was a hot summer day, the sun was directly over head, the fence and garage block any breeze, suddenly the oil soaked weeds ignited. By the time we got around the corner the fire was huge, we did manage to put it out with garden hoses, a lesson was learned. A good example of a human caused wild fire, via spontaneous combustion.
  I am sitting here writing this blog in a shroud of smoke, we don't know which fire is hanging in our air, we suspect the fire in Yosemite, however, there are several burning in Northern California right now. We have an "off shore" breeze which can blow smoke in from anywhere east of us, I don't think the fire in L.A. is part of our problem. Wild fires release huge amounts of ash, cinders, sulfur dioxide, carbon dioxide which all add to smog which can be deadly to some people with health issues. There are 60,000-80,000 wild fires each year in the United States alone, world wide there are many more, no country, state or city is immune.

It's beautiful and fragile at the same time. 

  There are some "good" effects of wild fires, clearing heavily wooded areas that have decades of organic material's built up burn up easily. Leaving in their wake is bare ground, covered in ash and partly burned organic material all of which will degrade into the soil adding nutrients. Natural Nitrogen is one of the most useful and is in the highest concentration, the organic material will mulch into the soil as well. However one of the side effects is some vegetation needs heat to begin the germination of their seeds. The Giant Sequoia Redwood trees are the most recognized as being one of them. When I back packed I frequented an area that had burned, it was a heavily forested area just North of the Sequoia National Forest, in that space between that park and Yosemite. I hiked through the area every year for about 10 years, the area took a long time to start a recovery. The grass came first, then the little saplings started to grow, I never did see a full grown tree, even after 10 years, it did good things to Terra firma, but nothing for aesthetics. I do wonder how many people die from the after effects of wild fires, famine, dehydration, and respiratory issues being a few. The effects of fire go deeply, the emotional scars often last a life time, there are many stories of rescues gone wrong.
  Fire is a friend, a foe, a threat and a weapon, one of the most basic of catastrophic entities and the most ancient is still one of the most feared, respected and used. Fire is used to heat our homes, cook our meals, and used in processing plants, on the other hand, it is used for arson, torture and military weaponry. A fire must be one of the biggest contradictions we have ever been faced with, it always raises it's head up. Sometimes it appears where we think we are safe, Hurricane Harvey, four feet of water everywhere when a chemical plant ignites, then the news focuses on a burning house, everything was soaking wet but fires still started.
  We are in the midst of Wild Fire Season now in the western United States, I expect to see some starting in the Diablo range to the west of us, at the same time praying for early rain, and no rain in Texas. Talk about contradictory events, but you know as well as I that we are all in this together and we will make it through the other side, together.
  Thanks for reading, leave a comment and tell me what you think.
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