Ember
Overview
 
Embers are the glowing, hot coals made of greatly heated wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...

, coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

, or other carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

-based material that remain after, or sometimes precede a fire
Fire
Fire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....

. Embers can glow very hot, sometimes as hot as the fire which created them. They radiate a substantial amount of heat long after the fire has been extinguished, and if not taken care of properly can rekindle a fire that is thought to be completely extinguished and can pose a fire hazard.
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Encyclopedia
Embers are the glowing, hot coals made of greatly heated wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...

, coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

, or other carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

-based material that remain after, or sometimes precede a fire
Fire
Fire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....

. Embers can glow very hot, sometimes as hot as the fire which created them. They radiate a substantial amount of heat long after the fire has been extinguished, and if not taken care of properly can rekindle a fire that is thought to be completely extinguished and can pose a fire hazard. In order to avoid the danger of accidentally spreading a fire, many campers pour water on the embers or cover them in dirt.

They are often used for cooking, such as in charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

 barbecue
Barbecue
Barbecue or barbeque , used chiefly in the United States, Canada, the United Kingdom, New Zealand and Australia is a method and apparatus for cooking meat, poultry and occasionally fish with the heat and hot smoke of a fire, smoking wood, or hot coals of...

s. This is because embers radiate a more constant form of heat, as opposed to an open fire which is constantly changing along with the heat it radiates.

An ember is usually formed when a fire has only partially burnt a piece of fuel, and there is still usable chemical energy in that piece of fuel. Often this happens because the usable chemical energy is so deep into the center that air (chemically O2) does not reach it, therefore not causing combustion
Combustion
Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame...

 (carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

-based fuel + O2 → CO2 + H2O + C + other chemicals involved). The reason that it continues to stay hot and does not lose its thermal energy quickly is because combustion is still happening at a miniature scale. The small yellow, orange and red lights often seen among the embers are actually combustion. There just is not enough combustion happening at one time to create a flame
Flame
A flame is the visible , gaseous part of a fire. It is caused by a highly exothermic reaction taking place in a thin zone...

. By the time embers are completely 'burned through', almost all of it is pure carbon will have loose physical bonds, which is why they crumble with the slightest touch. At that point they are normally called ashes.

Embers play a large role in forest fires. Since embers are typically burnt leaves and thus small and light, they can be blown away by the wind. During a large fire, with the right wind conditions, embers can be blown far ahead of the fire front, starting spot fires hundreds of metres away. One of the initial stages of defending against a bushfire is dubbed the "ember attack", in which embers will bombard the house, starting small fires in wooden structures.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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