Why do the caulk in between pool floor tiles look red, green, and blue and not white when looking through the water from the pool deck?

Question

Why do the caulk in between pool floor tiles look red, green, and blue and not white when looking through the water from the pool deck?

In: 1

Answer 1

The water in the pool is acting as a prism, separating the white light into its component colors.

When light crosses from a denser medium (water) into a thinner one (air) it deflects the angle. Different wavelengths deflect at slightly different angles and you can use this effect to break out the different colors of white light.