Why is water transparent ?

hi

Water is only transparent at certain frequencies of light, being especially transparent in the visible spectrum.

This shows how it's opacity across the whole spectrum. Notice how much it absorbs outside the visible spectrum. This makes communicating with submarines a real pain.

The gasses in the atmosphere follow the same basic transparency profile, with a few more spots of transperancy throughout the spectrum.

Transparency/opacity is determined by how much of the incoming e/m wave is absorbed and re-emitted by the material.

. If it just absorbs it all then it's opaque, but if the electron orbitals start re-emitting the absorbed wave then the wave can keep leapfrogging through the material. Alternately, the material might be diffuse and a lot of light can just pass through unabsorbed at all.

A substance's interaction with light is all about interactions between photons and atomic/molecular electrons. Sometimes a photon is absorbed, the absorber lingers a fantasctically short while in an excited state and then a new photon is re-emitted, leaving the absorber in exactly the same state as it was before the process. Thus the absorber's momentum, energy and angular momentum are the same as before, so the new photon has the same energy

water is transparent at visible wavelengths because (1) molecular resonances and other mechanical absorbing phenomena don't tend to be excited in water at visible wavelenghts and (2) it is optically homogeneous, which property is greatly helped by its being a liquid.

Water is not transparent for deepUV and infrared. From the evolutionary point of view our eye developed to see electromagnetic radiation present at earth in the past (and now) - deep UV and infrared are absorbed by water vapor and other gasses in atmosphere - so there were nothing to see at these wavelengths.

Pure water is transparent because it is a liquid. Objects that are not transparent either scatter light, due to difference in refractive index between air and the substance or they absorb all the photons at the wavelength you are observing.

In fact liquid water is blue if you look through enough of it, such as a metre or more. You can do this easily as an experiment. Molecules absorb energy in the microwave, infra-red and visible and ultra-violet parts of the spectrum.

While relatively small quantities of water appear to be colorless, water's tint becomes a deeper blue as the thickness of the observed sample increases.

The blue hue of water is an intrinsic property and is caused by the selective absorption and scattering of white light. Impurities dissolved or suspended in water may give water different colored appearances.

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 light turquoise blue color is caused by weak absorption in the red part of the visible spectrum

Many people wander why water has a clear, pristine appearance while so many other liquids seem to have at least minimal color.

The answer is a complex one and it all begins with the molecular make-up water. Water is entirely composed of hydrogen and oxygen. Both elements are gases in nature and are invisible.

Its origins lie in the way the water molecule interacts with incoming light.

The molecule’s two hydrogen atoms sit at the ends of two spring-like ‘legs’ joined midway by the oxygen atom.

The resulting V-shaped combination can vibrate in various ways, mopping up different wavelengths of light.

But it’s particularly effective at absorbing longer, redder wavelengths, while leaving shorter, bluer wavelengths fairly untouched.

The result is a pale blue colour. Water scatters shorter wavelengths more effectively, leading to more of the blue component of sunlight reaching our eyes.

The colour of a chemical is a physical property. In chemical world, all atoms or molecules are capable of absorbing and releasing the energy.

The colour of chemicals actually comes from the excitation of electrons due to absorption of energy performed by the chemical.

The colour of a chemical noticed by our eyes is the complementary colour that is generated due to release of the absorbed energy wavelengths.