Main Question or Discussion Point
when someone welds , why does it emit blue light , is it because of the ntirogen in the air.
I think the reason that arc discharge in air looks blue (just like lightning), is because O2 molecules are easier to ionize (lower ionization energy) and therefore, ionized O2 emits blue color.Welding uses/has a very high amount of energy. From E=hf, high energy implies a high frequency of light scattered/emitted. And blue light has a higher frequency than red, green yellow etc...