Friday, December 12, 2014

Why is the sky blue? (and other blue questions)

Sky & ocean & a sailing boat & a palm tree in the wind - yes, this photo is almost "kitschig" in its beauty, but that's how the view from the southern end of Lanzarote island looks on sunny days: blue sky, blue ocean, and the blue silhouette of Fuerteventura island in the distance.

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 friday
More blue moments from everywhere at photo friday

Have a beautiful sky week ~


Su-sieee! Mac said...

In other words, magic. :-)

ladyfi said...

Magical shots.

Joyful said...

Yes, I agree magic! Beautiful shot. x

Dorothee said...

thanks! it really is a magical place, and so nice that the sailing boat appeared just at that time.

indah nuria Savitri said...

true blue..and its magic will always captivate our hearts :)..cheers..

Francis Juif said...

And that's why, seen from the Moon, the Earth looks blue.