Eli5: What are you seeing when you look at fire? Not the logs, but the part up high that’s emitting light?
In: Chemistry
There is an exothermic (gives off heat) chemical reaction between the air and the carbon in the logs. The color of the flame (usually yellow in this case) is a good indication of the flame’s temperature.
You are seeing the heat being released by the chemical reaction that shows up as a color of a certain wavelength.
On your gas stove, natural gas and air produce a blue colored flame, which is a higher temperature than the flame produced by the log.
https://maggiemaggio.com/color/2011/08/fire-ii-color-and-temperature/
Oxygen is electro negative, and is violently stealing electrons from the fuel.
Im a firefighter and have been trying to figure out what the actual flame is for forever. It’s tough to understand and I don’t have it all figured out.
Btw the “glow” everything has isn’t the flame. As people have said, the glow on logs or something is that heat that everything has entering into the visible spectrum, but the flame is different i think. Though I could be wrong.
Btw, did you know the flame of a candle is hollow?
Fun fact! When things get hot they give off light!
Even you! Just not enough to actually see.
When you look at the colourful part of a flame what you’re seeing is super hot ash basically.
Burning things don’t just disappear into nothing, they get turned into the ash and soot and smoke that gets left behind.
This super hot material gives off the light you see when you’re looking at a fire. Because heat rises this is going up into the air in a satisfying flickering fashion creating the effect of fire that we all know.
In the case of gas burners it’s pretty much the same. “But gas is invisible” I hear you say. Well.. sort of. We’re still in the realm of hot particles being shiny.
That’s a topic for another time though.
Yellow flames are basically hot carbon particles due to incomplete combustion. They emit infrared and visible light just like any other material heated to red or white heat. Hold something like a spoon just above a candle flame and you will collect black carbon particles (soot).
Something like the blue flame of a Bunsen burner or a gas cooker burner is radiation from excited atoms. The combustion is complete so you don’t get yellow flames or soot.
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