Fine fuels 1-hour fuel are those fuels whose moisture content reaches equilibrium with the surrounding atmosphere within one hour. Fuels may be referred to as 1 hour, 10 hour, etc. Fuel moisture will increase during periods of rain or snow and high humidity. Sunlight will lower the relative humidity and increase the temperature resulting in the fuel losing moisture. The longer fuel is exposed to dryer conditions, the dryer it will get. Wind will also help to dry fuel.
It will blow away the moisture laden air next to the fuel and replace it with drier air. At night, surface temperature drops fairly rapidly, atmospheric moisture R. As a result, fuels will not continue to lose moisture to the atmosphere. In most cases, it will begin to draw moisture from the now damp air adjacent to them. Even though pine needles are fine fuels and can exchange moisture rapidly, they give off moisture very slowly when on the ground and compacted, because they are in a more moist environment.
The moisture in the adjacent needles and the space in between stays wetter because the sunlight and air with lower relative humidity is exposed only to the top layer.
Consequently they will react more like larger size fuel. They also absorb more moisture from precipitation because the excess does not all run off but is held by the ground. As these fuels lose moisture, they in turn will absorb more moisture from the ground. Draped fuels that are caught on limbs and brush will dry out rapidly because they are exposed to the sunlight and wind.
Only dead fuels interact with the adjacent air in the exchange of moisture. Green fuels gain and lose moisture on a seasonal basis or severe droughts. They are usually the highest in moisture content in the spring and are the lowest in the winter when in the cured stage. It is necessary to weigh a sample of fuel then dry it in an oven to determine the moisture content. The process requires a substantial amount of time and is not readily available on the fire line though new devices for measuring fuel moisture are becoming available.
Monitoring fine fuel moisture through the day, diurnal cycle, is an important fire line task to insure that the prescribed burn is within prescription parameters. See the segment on fuel models. Shape affects the ignition and behavior of fire much the same as size.
Flat shaped fuel is similar to small size fuel in that it has a larger surface-to-volume ratio. It dries out faster and there is also more surface area for the heat to enter, thus it will ignite more readily because it takes less heat to dry it out. It will also burn more rapidly contributing its heat energy to the fire quicker resulting in a more intense fire.
Fuels shapes:. A large log, wet from winter precipitation dries through the summer from the outside in. In the fall, as rains begin and temperatures and humidities moderate, the process is reversed and the log begins to take on moisture from the outside in.
Fuel's Effect on Fire Behavior The various weather elements that affect fire behavior, are interrelated and affect each other. Forecasts suggest it will become an even greater part of the U.
Unearthing, processing, and moving underground oil, gas, and coal deposits take an enormous toll on our landscapes and ecosystems. The fossil fuel industry leases vast stretches of land for infrastructure such as wells, pipelines, access roads, as well as facilities for processing, waste storage, and waste disposal. In the case of strip mining, entire swaths of terrain —including forests and whole mountaintops —are scraped and blasted away to expose underground coal or oil.
Even after operations cease, the nutrient-leached land will never return to what it once was. As a result, critical wildlife habitat —land crucial for breeding and migration —ends up fragmented and destroyed.
Coal, oil, and gas development pose myriad threats to our waterways and groundwater. Coal mining operations wash acid runoff into streams, rivers, and lakes and dump vast quantities of unwanted rock and soil into streams. Oil spills and leaks during extraction or transport can pollute drinking water sources and jeopardize entire freshwater or ocean ecosystems. Fracking and its toxic fluids have also been found to contaminate drinking water, a fact that the Environmental Protection Agency was slow to recognize.
Meanwhile, all drilling, fracking, and mining operations generate enormous volumes of wastewater , which can be laden with heavy metals, radioactive materials, and other pollutants.
Industries store this waste in open-air pits or underground wells that can leak or overflow into waterways and contaminate aquifers with pollutants linked to cancer, birth defects, neurological damage, and much more. Indeed, some These include benzene linked to childhood leukemia and blood disorders and formaldehyde a cancer-causing chemical.
Mining operations are no better, especially for the miners themselves, generating toxic airborne particulate matter. Fossil fuels produce large quantities of carbon dioxide when burned. Carbon emissions trap heat in the atmosphere and lead to climate change. In the United States, the burning of fossil fuels, particularly for the power and transportation sectors , accounts for about three-quarters of our carbon emissions.
Fossil fuels emit more than just carbon dioxide when burned. Coal-fired power plants singlehandedly generate 42 percent of dangerous mercury emissions in the United States, as well as two-thirds of U. Meanwhile, fossil fuel—powered cars, trucks, and boats are the main contributors of poisonous carbon monoxide and nitrogen oxide , which produces smog and respiratory illnesses on hot days.
Our seas absorb as much as a quarter of all man-made carbon emissions. Since the start of the Industrial Revolution and our coal-burning ways , the ocean has become 30 percent more acidic.
As the acidity in our waters goes up, the amount of calcium carbonate—a substance used by oysters, lobsters, and countless other marine organisms to form shells—goes down. This can slow growth rates, weaken shells, and imperil entire food chains. Ocean acidification impacts coastal communities as well. State and federal incentives, along with falling prices, are pushing our nation —and the world —toward cleaner, renewable energy sources such as wind and solar.
Renewables are on track to become a cheaper source of energy than fossil fuels, which is spurring a boom in clean energy development and jobs. Significantly higher levels of renewables can be integrated into our existing grid, though care must be taken to site and build renewable energy responsibly.
It accounts for more than 2. If we can put the right policies in place, we are poised to make dramatic progress toward a clean energy future. During combustion, new chemical substances are created from the fuel and the oxidizer.
These substances are called exhaust. Most of the exhaust comes from chemical combinations of the fuel and oxygen. But the exhaust can also include chemical combinations from the oxidizer alone.
The temperature of the exhaust is high because of the heat that is transferred to the exhaust during combustion. Because of the high temperatures, exhaust usually occurs as a gas, but there can be liquid or solid exhaust products as well. Soot , for example, is a form of solid exhaust that occurs in some combustion processes.
During the combustion process, as the fuel and oxidizer are turned into exhaust products, heat is generated. Interestingly, some source of heat is also necessary to start combustion.
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