What makes fire burn UP?

Why down, up left?

What pysical part of fire make it burn the way it does?

heat. hot air rises. same for hot plasma in flame. it's much hotter than the surrounding air, and thus, it rises UP. of course, if you wanted different shapes of fire, i hear fire comes as spheres in zero-G, where no gravity exists to force the lighter matter "up", if there is such a thing in space. i doubt you'll check back to this message, but if you do, there ya go :D

I don't know if we have any things here on earth able to make 0-G or anything, but I am ABSOLUTELY sure you cannot have traditional combustion reactions like we are used to. You need to have O2 to have any fires... And there isnt any O2 in space.

You need to have O2 to have any fires... And there isnt any O2 in space.

Zero-G doesn't necessarily mean Zero-Oxygen. Look at the videos of astronauts floating around in the space-station. That is Zero-G, but the habitat is fed oxygen for the astronauts. Of course they would not want to light a fire in there, it would consume their precious oxygen that they need to live!

We do sorta have ways to make Zero-G here on Earth. They take a plane up to a very high altitude, then do a nose dive at a certain angle. This creates a Zero-G atmosphere for a few minutes of training for astronauts.

As for the original question, when fire burns, the combustion heats the air that it consumes and the air around it. This makes the air less dense, thus lighter, and makes it rise above the cooler, denser air. Of course in space, there is no gravity, so the air (assuming an environment with oxygen is provided) is not affected like on earth. This makes very poor conditions for fire. That is because on Earth, when oxygen is used by a fire, the exhaust fumes rise up, as explained earlier, and are replaced by fresh oxygen. In a Zero-G environment, the fire's exhaust fumes would just sit where they were burned, and assuming no outside influences forced the cycling of oxygen, the fire would go out because it wouldn't recieve fresh oxygen to burn. They have done experiments in a closed environment in space, and have found that candles go out after a very short period of time because they use up their supply of oxygen in their immediate vicinity.

An easy solution to this is a solid fuel and oxydizer mixture, where no air movement is necessary for combustion, hence the solid fuel cells they use in rockets today.

Gravity "jfc!"

What makes fire burn UP? Why down, up left? What pysical part of fire make it burn the way it does?Fire releases heat, and heat causes the buring gases to expand. When they expand, they become less dense than the surrounding air, which is just another gas. The heavier, cooler gas sinks because it is heavier, so the buring gas rises by default.

ya'know there is a thread (on this site somewhere) that tells you how to make balls of plasma(fire) in a microwave useing a grape.