During combustion, atoms rearrange themselves irreversibly. Fire also is a glowing reminder of the oxygen that pervades our world. Any flame requires three ingredients: oxygen, fuel and heat. As an ingredient of air, oxygen is usually the easiest to find. On planets such as Venus and Mars, with atmospheres containing far less oxygen, fires would be hard to start. Any number of sources may supply heat. In the Avalanche Fire, lightning delivered the heat.
Fuel is what burns. People feel heat as warmth on the skin. Not atoms. The building blocks of all materials, atoms just get antsy as they warm. The flame ignites gases being emitted, and the fire spreads. As long as there is enough fuel and oxygen, the fire keeps burning. In complete combustion, the burning fuel will produce only water and carbon dioxide no smoke or other products. The flame is typically blue.
For this to happen, there needs to be enough oxygen to combine completely with the fuel gas. Many of us use methane gas CH 4 , commonly known as natural gas, at home for cooking. When the gas is heated by a flame or spark and if there is enough oxygen in the atmosphere, the molecules will break apart and reform totally as water and carbon dioxide. If there is not enough oxygen available during a chemical reaction, incomplete combustion occurs, and products such as carbon C and carbon monoxide CO as well as water and carbon dioxide are produced.
Less heat energy is released during incomplete combustion than complete combustion. Wildfires — what are they? What causes them? Over time, combustible materials such as smoldering embers can reach their ignition temperature. The fire triangle is a simple way of understanding the elements of fire. The sides of the triangle represent the interdependent ingredients needed for fire: heat, fuel and oxygen. A heat source is responsible for the initial ignition of fire, and is also needed to maintain the fire and enable it to spread.
Heat allows fire to spread by drying out and preheating nearby fuel and warming surrounding air. Fuel is any kind of combustible material. When it gets going, a fire is like a living thing.
It needs to be fed, sustained, and looked after, or it will die. You can find plenty of diagrams for building campfires: teepee designs , log cabin designs, elaborate plans for digging underground air-intake vents.
This rule comes from Bejan, who thought of it while watching a mound of charcoal ignite in his backyard grill. He realized when a fire is built into a pyramid shape, it will burn the hottest for the longest amount of time. The extreme is to have a skinny, stick-like pile. That, too, is a bad design. Bejan published this finding in the journal Scientific Reports. To him, the universality of the fire shape is evidence that humans have an innate sense of physics. If a fire burned perfectly, the log would be completely torn down into carbon dioxide and water vapor.
But most fires do not burn perfectly. And as a result, wood smoke contains a lot of pollutants: chemicals like benzene and formaldehyde, as well as fine particles that can irritate lungs and eyes.
As Brad Plumer has explained, indoor air pollution from wood smoke is the deadliest environmental hazard on the planet. But the hotter a fire burns, the more these toxic chemicals can get broken down into simpler, safer ones. Burning dry wood also helps keep these pollutants to a minimum. Fine particles from the smoke and soot can be smaller than 2. Fine particles also can aggravate chronic heart and lung diseases — and even are linked to premature deaths in people with these conditions.
The particles from wood smoke also can contribute to smog and haze. In Minnesota, for instance, where recreational outdoor fires are popular, Herschberger says recreational wood smoke accounts for around 5 percent of all the fine particles released to the air.
In terms of carbon dioxide emissions, wood smoke can be carbon neutral if the wood you burn is replaced by new growth. On the small scale, fire is predictable. It makes fire on a mountainside absolutely magical, unpredictable. Like dark magic? With ongoing drought, climate change, and, ironically, a history of fire suppression , forest fires in the Western US have been growing bigger and more destructive over time.
A lot of these fires are started by lightning.
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