Why is water clear? How does light go through it?

Water is full of stuff.... how is it possible for light to go through it?





same goes for glassWhy is water clear? How does light go through it?
stuff will absorb light if it can resonate with energies equal to the energies of the photons in light (or if it has free electrons that can absorb most any energy as in a metal).





Water mollecules have rotational resonances in the microwave energies (which is why microwaves heat water so well) and vibrational resonances in the near infrared (which leak slightly into the red side of visible, giving water a slightly bluish color).Why is water clear? How does light go through it?
Light goes through it because though something may appear solid it is surprisingly empty. See Rutherford's gold foil experiment where he showed that gold is actually mostly free space; that experiment found the nucleus.





Now, you are unfortunately putting a very limited view of the world on the water and not even realizing it. You say it is clear. But you didn't say where! You obviously mean that it is clear at visible wavelengths. The atmosphere is much like that, and we often say how clear the sky is tonight (not referring to cloud cover, but to how well we can see the stars).





Unfortunately our atmosphere is not so clear at other frequencies / wavelengths / energies (its all the same). For example, the atmosphere blocks virtually all xrays from outerspace from hitting us. This is a good thing. But if you want to look at the X-Ray output of other galaxies and stellar objects you can't do this from the ground. You need to put a satellite in orbit, like they did with Chandra.





So, basically, water is clear to us at the visible wavelengths because a) it does not absorb the light through nuclear processes, b) a coincidence that we can see light at 300-700nm and water does not absorb much at these wavelengths. Believe me, our eyes could have evolved differently and we could see microwaves, radio or xrays. Imagine if we could see in xray. We would never see outside our atmosphere. The sun would not be visible and we would not see a bright day -- only feel the sun's warmth. What a truly strange place. And imagine in radio -- we would need to have eyes much bigger than they are now so that we could resolve images. Even then our vision would not be as precise as it (barring those with glasses, of course).