We went to North Berwick on the Edinburgh coast. This picture shows the amazing Bass Rock on the right. They used to keep prisoners on it due to the ridiculously high sheer cliffs. The white top is actually due to big sea birds called gannets. What caught my attention was the strip of bright blue on the sea below the islands.
The blue strip is clearer on this picture. Notice that there is blue sky behind it.
In this last picture, there are clouds behind, and the sea isn't blue. I was thinking a lot at Easter about why the sea sometimes seems blue and I think that this day convinced me that a lot of it must be due to the reflection of blue light coming down from the sky. As noted in an earlier piece, it is the blue photons that are scattered in our direction by the atmosphere which is why the sky looks blue.
The next set of questions to answer will be to do with reflectivity. How much of the light falling on the sea is reflected? Some light must penetrate the water because it used by algae. How much of the light coming back off the surface of the sea has actually come from underwater and been refracted up to us? This must happen because in some places we can see the bottom of the sea or things submerged in the water.
Finally, if you've never been to Bass Rock, you must go. It is awesome!
