Eli5: How come fire flames go upwards and why do the flames always “dance” around?
In: 285
Density and gravity are your two reasons for rising.
As a gasses from the fire heat up, their molecules move further apart. This makes the hot gas less dense. If its less dense, the denser gasses above these hot fire-gasses, sink below them. So, the fire gasses get higher and higher. A good analogy is a hot air balloon. The gasses within the balloon are heated up whenever the pilot wants to rise. Denser, cooler gasses outside of the balloon, sink below it and therefore the balloon goes up.
Gravity…. Without it, the gasses that are cooler than the fire gasses would not sink beneath them. That’s why your in space flame is round.
The dancing around is basically turbulence from cool gasses interacting with hot gasses and then trading places at a high rate of knots. That is basic, I’m no scientist and I’m super happy to be corrected and learn new stuff.
Source – I’m am ex fire behaviour instructor from UK fire service.
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