Blue teal and green paint splatter background
Because most lakes and oceans contain suspended living matter and mineral particles, light from above is scattered and some of it is reflected upwards. A few tens of meters of water will absorb all light, so without scattering, all bodies of water would appear black.
Scattering from suspended particles also plays an important role in the color of lakes and oceans, causing the water to look greener or bluer in different areas. The hue of the reflected sky contributes to the perceived blue color of water, but much of the blue color comes from light scattering by small particles. The relative contribution of reflected skylight and the light scattered back from the depths is strongly dependent on observation angle. This is the main reason the ocean's color is blue. The red, orange, yellow, and sometimes green wavelengths of light are absorbed so the remaining light seen is composed of the shorter wavelength blues and violets. Water molecules can vibrate in three different modes when they interact with light. Some of the light hitting the surface of ocean is reflected but most of it penetrates the water surface, interacting with water molecules and other substances in the water. The deeper the pool, the bluer the water. Water in swimming pools with white-painted sides and bottom will appear as a turquoise blue, even in indoor pools where there is no blue sky to be reflected. While this reflection contributes to the observed color, it is not the sole reason. One is that the surface of the water reflects the color of the sky. Lakes and oceans appear blue for several reasons. For this reason, the pipe needs to have a length of a meter or more and the water must be purified by microfiltration to remove any particles that could produce Mie scattering. Ībsorption intensity decreases markedly with each successive overtone, resulting in very weak absorption for the third overtone. For this reason, heavy water does not absorb red light and thus large bodies of D 2O would lack the characteristic blue color of the more commonly-found light water ( 1H 2O). The absorption curve for heavy water (D 2O) is of a similar shape, but is shifted further towards the infrared end of the spectrum, because the vibrational transitions have a lower energy. In liquid state at 20☌ these vibrations are red-shifted due to hydrogen bonding, resulting in red absorption at 740 nm, other harmonics such as v 1 + v 2 + 3v 3 giving red absorption at 660 nm. The absorption in the visible spectrum is due mainly to the harmonic v 1 + 3v 3 = 14,318 cm −1, which is equivalent to a wavelength of 698 nm. Absorption due to these vibrations occurs in the infrared region of the spectrum. Two stretching vibrations of the O-H bonds in the gaseous state of water occur at v 1 = 3650 cm −1 and v 3 = 3755 cm −1. The water molecule has three fundamental modes of vibration. Water is a simple three-atom molecule, H 2O, and all its electronic absorptions occur in the ultraviolet region of the electromagnetic spectrum and are therefore not responsible for the color of water in the visible region of the spectrum.
Ībsorptions in the visible spectrum are usually attributed to excitations of electronic energy states in matter. The light turquoise blue color is caused by weak absorption in the red part of the visible spectrum. The intrinsic color of liquid water may be demonstrated by looking at a white light source through a long pipe that is filled with purified water and closed at both ends with a transparent window. The same water in a smaller bucket looks only slightly blue, and observing the water at close range makes it appear colorless to the human eye. An indoor swimming pool appears blue from above, as light reflecting from the bottom of the pool travels through enough water that its red component is absorbed.