First, the temperature of the flame determines the color of the flame. The flame emitted by the burning branches will gradually change with the temperature of the flame. During the fire, the temperature was high and the light color was Huang Liang. The flame gradually goes out, the temperature decreases, and the flame gradually changes from bright yellow to orange, red and dark red.

Second, the elemental composition of the burning substance determines the spectrum of the flame. Each element in the element list will emit its own specific light color at high temperature. For example, sodium is yellow, potassium is purple and copper is green. The light color of the compound is variegated, because many elements emit light.

The main component of natural gas is methane, and the gas itself should be colorless or red. However, natural gas is combined with oxygen in the core of the flame, which cannot be completely burned due to lack of oxygen, resulting in partial carbon monoxide, which fully reacts with oxygen in Flametail, resulting in a blue-green flame.