The color spectrum is much larger than we can perceive! The range moves from invisible, low-energy infrared rays to high-energy ultraviolet rays. The ‘visible light spectrum’, or the colors that we see, are actually in the middle of the range.
Normal color absorbs and re-emits a portion of the visible spectrum that matches its principal wavelength, while the remaining colors are absorbed and dissipated as heat. In this way, a regular orange color re-emits back to your eye just the narrow orange band of the visible light spectrum. Therefore, if there is little or no orange light around (such as early dawn or dusk) the orange surface would appear dark or even black.
How do fluorescent colors behave differently?
Fluorescent colors use a larger amount of both the visible spectrum and the lower wavelengths compared to conventional colors. They not only absorb and convert light energy of the dominant wavelength, but also the wavelengths of ultraviolet rays and other colors lower in the visible spectrum. As a result, your eye perceives a far more intense color.
Where a clean, bright conventional color is able to reflect a maximum of 90% of a color present in the spectrum; a fluorescent color can reflect as much as 200% to 300%
