Why is water blue?
While there, a question of the obvious came up: why is water blue? I first guessed that the blues of the water is simply the blue of the sky, reflected, but that only leads to the next question: why is the sky blue?
Later that day, and reconnected to wifi, I looked for the answer to the blue. Turns out, water itself is blue - or rather: water looks blue. Here's the explanation: bodies of water appears blue from above, as they absorb the red component of the light that is reflecting from the bottom of them. The effect is stronger when the water is deeper. If you put the same water in a smaller bucket it only looks slightly blue.
But that is only part of the answer. In addition to that, Lakes and oceans appear blue as the surface of the water reflects the color of the sky. Which leads back to the other tricky question:
Why is the sky blue?
Nasa has the answer, here's a short version: "Sunlight reaches Earth's atmosphere and is scattered in all directions by all the gases and particles in the air. Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time."
More about it, here: nasa/sky
More skies from everywhere: skywatch fridayMore blue moments from everywhere at photo friday
Have a beautiful sky week ~