<p>For each wavelength of light there is a certain spectral color. White light comprises of a multitude of spectral colors varying in intensity. The more lines "fill" the spectrum the better is the color output of lamps. Lamps have according to their type different spectral distribution : Heat/Temperature (incandescent) lights have a continuous spectrum, high pressure and low pressure sodium/halogen lamps the spectrum depends on the "ingredients" - for example, the halogen in metal halide lamps or the proportions of the phosphors in fluorescent lamps. Daylight also has a certain spectral distribution.</p>