How does a flame appear yellow when what's above the heat source is just air?

5 Answers

  • 4 months ago
    Favorite Answer

    There are various reasons.

    One is the presence of impurities in the material being burned. In a candle, for example, the wax is heated and melted by the flame above it; the liquid goes up the wick by capilarity where it is heated some more and vaporizes into the air where it is burned by the heat and the oxygen of the air.

    Another is the temperature of the flame (see color temperature)

    Another still is the binding energy being released by the combustion. In the case of carbon, for example, when one atom of carbon combines with two atoms of oxygen, it liberates a few electronVolts of energy as photons of light, many of them being in the visible part of the spectrum.

    And the list goes on

  • Anonymous
    4 months ago

    Gas excitations produce a signature line emission spectrum for an element. In comparison, incandescence produces a continuous band of light with a peak dependent on the temperature of the hot object.When the atoms of a gas or vapor are excited, for instance by heating/burning or by applying an electrical field, their electrons are able to move from their ground state to higher energy levels. As they return to their ground state, following clearly defined paths according to quantum probabilities, they emit photons of very specific energy. This energy corresponds to particular wavelengths of light, and so produces particular colors of light. Each element has a "fingerprint" in terms of its line emission spectrum, thus gases and other elements can be identified based upon the color they burn.

  • 4 months ago

    I'll assume that you're referring to gas flame color.

    Air is 80% Nitrogen which doesn't support combustion.

    Gas (Methane, Ethane, Propane, Butane, etc.) must

    be mixed with air before it's ignited for a clean, blue flame.

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  • User
    Lv 7
    4 months ago

    The flame IS the heat source (or: part of the heat source, in some cases).

    It emits light of different colors.

    If you're talking about a fire

    hot, miniscule particles from the fire rise in the air (because they are hot)

    and continue to combust

    thus: forming a flame.

    More info:

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  • Anonymous
    4 months ago

    Because of the combustion of the fuel, that's not just air.

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