question: Why do flames always burn upward? When you light a match, why do they continue to burn upward even if you twist the match around in your fingers, or flip it upside down?
comment: Put simply, hot air rises, however given a strong enough current flames can be sucked any direction, and in specific conditions even lay down and stick to the surface of objects
passages: Section::::Flame lift-off height.
   Reaction is initiated by an activating energy, in most cases, it is heat. Several examples include friction, as in case of matches, heating an electrical wire, a flame (propagation of fire), or a spark (from a lighter or from any starting electrical device). There are also many other ways to bring sufficient activation energy including electricity, radiation, and pressure, all of which will lead to a temperature rise. In most cases, heat production enables self-sustainability of the reaction, and enables a chain reaction to grow. The temperature at which a liquid produces sufficient vapor to get a flammable mix with self-sustainable combustion is called its flash-point.
   According to Nickell and Fischer's investigation, nearby objects often remained undamaged because fire tends to burn upward, but burns laterally with some difficulty. The fires in question are relatively small, achieving considerable destruction by the wick effect, and relatively nearby objects may not be close enough to catch fire themselves (much as one can closely approach a modest campfire without burning). As with other mysteries, Nickell and Fischer cautioned against "single, simplistic explanation for all unusual burning deaths" but rather urged investigating "on an individual basis".
   The surface of the fireball, with a temperature over 20,000 kelvins, emits huge amounts of visible light radiation, more than 100 times the intensity at the Sun's surface. Anything solid in the area absorbs the light and rapidly heats. The "rope tricks" that protrude from the bottom of the fireball are caused by the heating, rapid vaporization and then expansion of guy wires (or specialized rope trick test cables) that extend from the shot cab, the housing at the top of the tower that contains the explosive device, to the ground. Malik observed that when the rope was painted black, spike formation was enhanced, and if it were painted with reflective paint or wrapped in aluminium foil, no spikes were observed – thus confirming the hypothesis that it is heating and vaporization of the rope, induced by exposure to high-intensity visible light radiation, which causes the effect. Because of the lack of guy wires, no "rope trick" effects were observed in surface-detonation tests, free-flying weapons tests, or underground tests.
   Under controlled conditions (typically in a laboratory) a laminar flame may be formed in one of several possible flame configurations. The inner structure of a laminar premixed flame is composed of layers over which the decomposition, reaction and complete oxidation of fuel occurs. These chemical processes are much faster than the physical processes such as vortex motion in the flow and, hence, the inner structure of a laminar flame remains intact in most circumstances. The constitutive layers of the inner structure correspond to specified intervals over which the temperature increases from the specified unburned mixture up to as high as the adiabatic flame temperature (AFT). In the presence of volumetric heat transfer and/or aerodynamic stretch, or under the development intrinsic flame instabilities, the extent of reaction and, hence, the temperature attained across the flame may be different from the AFT.
   Color and temperature of a flame are dependent on the type of fuel involved in the combustion, as, for example, when a lighter is held to a candle. The applied heat causes the fuel molecules in the candle wax to vaporize. In this state they can then readily react with oxygen in the air, which gives off enough heat in the subsequent exothermic reaction to vaporize yet more fuel, thus sustaining a consistent flame. The high temperature of the flame causes the vaporized fuel molecules to decompose, forming various incomplete combustion products and free radicals, and these products then react with each other and with the oxidizer involved in the reaction. Sufficient energy in the flame will excite the electrons in some of the transient reaction intermediates such as the methylidyne radical (CH) and diatomic carbon (C), which results in the emission of visible light as these substances release their excess energy (see spectrum below for an explanation of which specific radical species produce which specific colors). As the combustion temperature of a flame increases (if the flame contains small particles of unburnt carbon or other material), so does the average energy of the electromagnetic radiation given off by the flame (see Black body).
   Section::::Major Theories.
  
  Section::::Major Theories.:Haidt's Third Dimension of Social Cognition.
   The oxidizer is the other reactant of the chemical reaction. In most cases, it is the ambient air, and in particular one of its components, oxygen (O). By depriving a fire of air, it can be extinguished; for example, when covering the flame of a small candle with an empty glass, fire stops; to the contrary, if air is blown over a wood fire with bellows, the fire is activated by the introduction of more air. In certain torches, gaseous oxygen is introduced to improve combustion.
   In the same way, as soon as one of the four elements of the tetrahedron is removed, combustion stops.
  
  Section::::Oxidizer.
   Section::::Flight techniques.:Sequence.:Flight.:Level flight.
  
  The burner is designed to create enough heat to warm up the balloon quickly. It is most efficient only when wide open. There is no good way to maintain the exact temperature required to maintain equilibrium.
  
  Add to that the fact that when a hot air balloon is not actively being heated, it is cooling off. This means that it is in perfect equilibrium only momentarily. The rest of the time it is either too warm or too cool and so either climbing or descending.
   The common distribution of a flame under normal gravity conditions depends on convection, as soot tends to rise to the top of a general flame, as in a candle in normal gravity conditions, making it yellow. In micro gravity or zero gravity, such as an environment in outer space, convection no longer occurs, and the flame becomes spherical, with a tendency to become more blue and more efficient (although it may go out if not moved steadily, as the CO from combustion does not disperse as readily in micro gravity, and tends to smother the flame). There are several possible explanations for this difference, of which the most likely is that the temperature is sufficiently evenly distributed that soot is not formed and complete combustion occurs. Experiments by NASA reveal that diffusion flames in micro gravity allow more soot to be completely oxidized after they are produced than diffusion flames on Earth, because of a series of mechanisms that behave differently in micro gravity when compared to normal gravity conditions. These discoveries have potential applications in applied science and industry, especially concerning fuel efficiency.
   Section::::Temperature.:Cool flames.
  
  At temperatures as low as , fuel-air mixtures can react chemically and produce very weak flames called cool flames. The phenomenon was discovered by Humphry Davy in 1817. The process depends on a fine balance of temperature and concentration of the reacting mixture, and if conditions are right it can initiate without any external ignition source. Cyclical variations in the balance of chemicals, particularly of intermediate products in the reaction, give oscillations in the flame, with a typical temperature variation of about , or between "cool" and full ignition. Sometimes the variation can lead to an explosion.
   Of the two brothers, it was Joseph who was first interested in aeronautics; as early as 1775 he built parachutes, and once jumped from the family house. He first contemplated building machines when he observed laundry drying over a fire incidentally form pockets that billowed upwards. Joseph made his first definitive experiments in November 1782 while living in Avignon. He reported some years later that he was watching a fire one evening while contemplating one of the great military issues of the day—an assault on the fortress of Gibraltar, which had proved impregnable from both sea and land. Joseph mused on the possibility of an air assault using troops lifted by the same force that was lifting the embers from the fire. He believed that the smoke itself was the buoyant part and contained within it a special gas, which he called "Montgolfier Gas", with a special property he called levity, which is why he preferred smoldering fuel.
   The motion picture films show the fire spreading downward along the skin of the airship. While fires generally tend to burn upward, especially including hydrogen fires, the enormous radiant heat from the blaze would have quickly spread fire over the entire surface of the airship, thus apparently explaining the downward propagation of the flames. Falling, burning debris would also appear as downward streaks of fire.
   In fires (particularly house fires), the cooler flames are often red and produce the most smoke. Here the red color compared to typical yellow color of the flames suggests that the temperature is lower. This is because there is a lack of oxygen in the room and therefore there is incomplete combustion and the flame temperature is low, often just . This means that a lot of carbon monoxide is formed (which is a flammable gas) which is when there is greatest risk of backdraft. When this occurs, combustible gases at or above the flash point of spontaneous combustion are exposed to oxygen, carbon monoxide and superheated hydrocarbons combust, and temporary temperatures of up to occur.
   Flame lift-off
  
  Flame lift-off in oil fired pressure jet burners is an unwanted condition in which the flame and burner become separated. This condition is most commonly created by excessive combustion air and often results in the loss of flame as the photo-electric cell fails to register the light of the flame, this in turn results in a safety lockout of the control box.
  
  Section::::Other outcomes.
  
  Other outcomes may be experienced: –
   In the year 2000, experiments by NASA confirmed that gravity plays an indirect role in flame formation and composition. The common distribution of a flame under normal gravity conditions depends on convection, as soot tends to rise to the top of a flame (such as in a candle in normal gravity conditions), making it yellow. In microgravity or zero gravity environment, such as in orbit, natural convection no longer occurs and the flame becomes spherical, with a tendency to become bluer and more efficient. There are several possible explanations for this difference, of which the most likely is the hypothesis that the temperature is sufficiently evenly distributed that soot is not formed and complete combustion occurs. Experiments by NASA reveal that diffusion flames in microgravity allow more soot to be completely oxidized after they are produced than do diffusion flames on Earth, because of a series of mechanisms that behave differently in microgravity when compared to normal gravity conditions. These discoveries have potential applications in applied science and industry, especially concerning fuel efficiency.
   In the gas phase, i.e. in the flames or in the smoke, the combustible can not be separated from the oxidizer, and the only possible action consists of cooling down. In this case, water droplets are evaporated in the gas phase, thereby lowering the temperature and adding water vapour making the gas mixture non combustible. This requires droplets of a size less than about 0.2 mm. In fire fighting, this is referred to as gas cooling or smoke cooling.
   By analysing the spectrum of the chromosphere, it was found that the temperature of this layer of the solar atmosphere increases with increasing height in the chromosphere itself. The temperature at the top of photosphere is only about 4,400 K, while at the top of chromosphere, some 2,000 km higher, it reaches 25,000 K. This is however the opposite of what we find in the photosphere, where the temperature drops with increasing height.
   Section::::Controversies.
   Cool flames were accidentally discovered in the 1810s by Sir Humphry Davy, who was inserting a hot platinum wire into a mixture of air and diethyl ether vapor. "When the experiment on the slow combustion of ether is made in the dark, a pale phosphorescent light is perceived above the wire, which of course is most distinct when the wire ceases to be ignited. This appearance is connected with the formation of a peculiar acrid volatile substance possessed of acid properties." After noticing that certain types of flame did not burn his fingers or ignite a match, he also found that those unusual flames could change into conventional ones and that at certain compositions and temperatures, they did not require an external ignition source, such as a spark or hot material.
   When heated, air expands, so a given volume of space contains less air. This makes it lighter and, if its lifting power is greater than the weight of the balloon containing it, it will lift the balloon upwards. A hot air balloon can only stay up while it has fuel for its burner, to keep the air hot enough.
  
  The Montgolfiers' early hot air balloons used a solid-fuel brazier which proved less practical than the hydrogen balloons that had followed almost immediately, and hot air ballooning soon died out.
   In "Axioms and Postulates" Schiller vindicates the postulation by its success in practice, marking an important shift from "Riddles of a Sphinx". In "Riddles", Schiller is concerned with the vague aim of connecting the "higher" to the "lower" so he can avoid scepticism, but by 1903 he has clarified the connection he sees between these two elements. The "higher" abstract elements are connected to the lower because they are our inventions for dealing with the lower; their truth depends on their success as tools. Schiller dates the entry of this element into his thinking in his 1892 essay "Reality and 'Idealism'" (a mere year after his 1891 "Riddles").
   BULLET::::- Thermal balance: The degree of thermal balance existing in a closed room during a fire's development is dependent upon fuel supply and air availability as well as other factors. The hot area over the fire (often termed the fire plume or thermal column) causes the circulation that feeds air to the fire. However, when the ceiling and upper parts of the wall linings become super-heated, circulation slows down until the entire room develops a kind of thermal balance with temperatures distributed uniformly horizontally throughout the compartment. In vertical terms the temperatures continuously increase from bottom to top with the greatest concentration of heat at the highest level.
   A sky lantern may land when the flame is still alight, making it a fire hazard. In typical designs, as long as the lantern stays upright the paper will not get hot enough to ignite, but if the balloon is tilted (say, by the wind or by hitting some object), it may catch fire while still in the air. All the paper will usually burn in a few seconds, but the flame source may remain lit until it hits the ground.
  
raw_presuppositions: Flames always burn upwards
raw_corrections: Flames can burn in any direction that the air takes it.