, eh? Lets browse
some theory together
1) A flame
is merely an extremely hot volume
of air (essentially around/inside where the combustion
takes place). When you have something on fire
, the heat from the 'burning
heats the surrounding
air causing it to emit light
. This light is the 'flame' that you see. The heat also causes a net
increase in particle
speed (in fact it is this that causes the light emission...); ie the gas
will attempt to expand
and in doing so lowers it's density
. In a gravitational field, the force
on a given volume is less than that of it's surrounding gas so the gas will tend to rise above it as well as directly outwards. This gives the flame it's characteristic appearance... (note the small part of the flame *under* the match head due to downward velocities temporarily
outweighing upward net force)
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2) The flame is allowed to burn because underneath it, the (unburned) air is *rising* to fill the gap that the (burned) air left. The candle actually evaporates it's fuel before burning it, so the flame doesn't start at the base of the wick (the fuel inside the flame is evaporated and the (melted) fuel inside the candle wax is taken up the wick by capillary action and eventually evaporates into the flame itself).
3) Finally, the candle wick is pulled downward by gravity, causing it to bend and where it nears the edges of the flame (the hottest point) the wick itself is combusted and is destroyed.
1) With the gravity taken away, the flame loses it's appearance. All forces acting upon the flame are now equal so the flame becomes symmetrical, ie a sphere
(the sphere will 'wobble' due to fluctuations
in the air, mind).
2) In this case, the huge flame noted with the candle example cannot exist - unused, oxygen rich air needs a route to the burning material and it cannot obtain this route with a flame as large as in a gravitational field, therefore because the equality of forces acting upon the gas particles forces a spherical flame, the flame *must* shrink. The reduced flame size means there will be less emitted energy, hence the flame is cooler. Because the flame is cooler, and the necessity of melting the wax to sustain a flame, the flame itself exists far lower down on the wick. Note that in this case you can't overmelt the wax because instead of simply dripping down the sides, your wax will wobble off into space in a wobbly blob and create a small mess.
3) In a gravity free environment, the wick is no longer forced over to the side and so remains straight. As the flame is lower down on the wick, the wick itself will be burned sooner (at the top of the flame) and thus will be shorter. It's also worth noting that the flame's equality means it will be burning the bottom of the wick as well as the top. Cross your fingers and hope it doesn't sever itself ;).
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You're average candle probably won't stand up to the rigours of space - it will need a slow burning wick, a low melting point wax and probably won't be too interesting if it burned at all. I'd guess if you did burn one it was specially chosen/designed for space or you'd have problems.