Rainbow in Maoz Haim, Israel
Rainbow is created when
the sun light hits the rain drops. The rainbow is an excellent demonstration in
everyday life of the fact that the visible light is composed of several
wavelengths which correspond to the typical colors of the rainbow. In the question, you learned that a special
dye can be added to a body of water as a means of chemical reduction of
Cyanobacteria bloom. It was explained to
you that this dye blocks the light from passing through the water. But, actually
its exact mechanism is just blocking the red and blue wavelengths (colors) of
the light while allowing the other wavelengths of the light passing through the
water. The blue and red wavelengths are required for photosynthesis to occur.
Hence, their blockage by the dye prevents the Cyanobacteria to perform
photosynthesis. As they can no longer manufacture their food, the Cyanobacteria
stop proliferating and their bloom is reduced.