When the temperature is low, it is infrared. With the increase of temperature, the flame changes from red orange (3,000 degrees) to yellow white (4,000 degrees), blue blue (5,000-6,000 degrees) to purple (above 7,000 degrees), and finally invisible ultraviolet (tens of thousands of degrees), and the color is constantly changing.
From the point of view of high-energy physics, the flames in infrared and color spectra are low-energy flames. With the increasing temperature, the color of the flame ranges from ultraviolet rays to X rays to gamma rays. These are indescribable "colors".
Flame temperature:
Flame temperature is one of the main characteristics of flame. It has a great influence on the formation and dissociation of compounds in the flame, and thus on the atomization of the measured elements.
In the flame, on the one hand, the combustion reaction generates heat, on the other hand, the compounds in the flame dissociate, and heat is consumed in order to raise the equilibrium mixture in the flame to the flame temperature. The flame temperature is determined by the thermal balance between them. When the flame is in thermal equilibrium, the temperature can be used to characterize the true energy of the flame.