The sun radiates the full spectrum of electromagnetic energy. The atmosphere acts as a selective window that allows visible light to pass through while screening out a substantial fraction of other radiation. The visible range of light is the radiation that drives photosynthesis. Blue and red, the two wavelengths most effectively absorbed by chlorophyll, are the colors most useful as energy for the light reactions. The Light Receptors Light may be reflected, transmitted or absorbed when it contacts matter.
Different pigments absorb different wavelengths of light.
Wavelengths that are absorbed disappear, so a pigment that absorbs all wavelengths appears black. When white light, which contains all the wavelengths of visible light, illuminates a pigment, the color you see is the color most reflected or transmitted by the pigment. For example, a leaf appears green because chlorophyll absorbs red and blue light but transmits and reflects green light. Each pigment has a characteristic absorption spectrum or pattern of wavelengths that it absorbs. It is expressed as a graph of absorption versus wavelength.