What exactly is a flame made of? And why does it have that specific shape?
In: Physics
The primary thing making a flame is heat. There might be different reasons for this heat which may be visible in the shape and color of the flame. The classical shape and color of say a candle fire or a bondfire is caused by several things. Firstly most of the heat comes from volotile compounds which evaporates from the heat and then burns in the air. So as these hot gasses rises they actually increase in temperature until these volotile compounds have burned up by which time the temperature decreases as the gasses mix with cold air. At the same time the hot rising air creates a low pressure at its base due to a lack of air such that surrounding cold air gets pushed into the base cooling it down. So the flame itself is quite small at its base, growing bigger in the center and then tailing off into invisible temperatures higher up. For the color, hot things will glow with a color based on its temperature. First infrared, then red, orange and eventually white and even hot blue. And there is some of this color in the flame. However when you heat up things to ions they will glow in a specific color based on the element. This usually gives off far more light. In the case of a classical fire they usually have a lot of sot and other carbon based compounds which glows yellow when ionized. This is why flames are usually yellow.
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