# Why does fire go up?

Mattius_
Fire always points up. My thoughts are, the hot air it creates travels upwards, and with that, so do the firing photons within the atoms of the air, which would then create the image of the fire traveling upwards.

Am i right?

Homework Helper
Typically fire works something like this:
The fuel vaporizes, then the vapors burn. Since the vapors are hot, they radiate visible light. Since the air around them is hot, there is an updraft, so the hot material travels upwards.

In zero-g environments flames look different.

one_raven
Originally posted by NateTG
In zero-g environments flames look different.

I'd like to see that!

No gravity, no rising air to shape the flame.

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Mattius_

Neat! So that means that when a spaceship is taking off, and the jets are facing down, you get more thrust because the hot air is rebounding back to the jets??????????????

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Gold Member
That is SO COOL!! How would that effect take off on the moon or mars?
Or would it matter because of the giant thrust?

Mr. Robin Parsons
Originally posted by Mattius_
Neat! So that means that when a spaceship is taking off, and the jets are facing down, you get more thrust because the hot air is rebounding back to the jets??????????????
Thats more of "An equal and opposite reaction" Newton, flames burning, and the currents of air, that influence there shape, is more of a Chemistry > 'mixing' probelm/solution, with physics in the heat exchanges and molecular/atomic (subatomic, but I don't think/know if that's been explored) activities that arise as a result of all of the event(s) sequencing...sorta...

Mentor
Originally posted by Mattius_
Neat! So that means that when a spaceship is taking off, and the jets are facing down, you get more thrust because the hot air is rebounding back to the jets??????????????
Not really - the thrust is so high and the speed of the rocket so fast that convection has a minimal effect.