2. The Role of Temperature in Blue Lightning
Temperature of lightning is one of the main elements causing its blue hue. Usually, blue lightning is hotter than more often occurring white or yellow bolts. About five times hotter than the surface of the sun, a lightning bolt’s temperature may soar to 50,000 degrees Fahrenheit (27,760 degrees Celsius). The air molecules in the lightning channel become very energised at these very severe temperatures.
These superheated air molecules release light-forming energy when they calm down. Temperature affects the particular wavelengths of light emitted. Whereas cooler discharges produce more red and orange light, hotter lightning often emits more blue and violet light. This is the reason the hottest section of a flame is generally blue; the same is true of lightning.