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  ====Temperatures of flames by appearance====
  It is true that objects at specific temperatures do radiate visible light. Objects whose surface is at a temperature above approximately  will glow, emitting light at a color that indicates the temperature of that surface. See the section on red heat for more about this effect. It is a misconception that one can judge the temperature of a fire by the color of its flames or the sparks in the flames. For many reasons, chemically and optically, these colors may not match the red/orange/yellow/white heat temperatures on the chart. Barium nitrate burns a bright green, for instance, and this is not present on the heat chart.