Two Blues: The Sky's and the Water's

A horizon is a strange piece of luck for a photograph. It sets two blues side by side, edge to edge, with nothing in between to soften the comparison. The eye goes straight to that line and starts measuring, and within a second it has decided that the sky and the sea are not the same colour and never were.

The reasons are dull enough to be beautiful. The sky is thin, scattered light, more or less the same overhead all day. Water is borrowed: some of the sky lands on its surface, some of the light goes down and comes back missing its reds, and the rest is whatever sits on the bottom — sand, weed, ten metres of nothing. So the sea leans green near the shore and turns colder further out, while the sky above it stays flat and even. A polariser will change one and barely touch the other, which is the clearest proof that they are different things wearing the same name.

As a desktop this works quietly. Two large calm fields, a low-contrast seam between them, no detail competing with the icons. The only real decision is where to leave the line: low, and the screen is mostly sky and the dock has room; high, and you spend the day looking at water. Either way the picture holds still, which is more than most pictures manage.