Yesterday was cold and clear, wonderful for a beach walk.
But what am I seeing? This is the Block Island Ferry but it is NOT in the right place
It is coming in head-on ??? It will hit the rock with the seagull! [And I have not photo-shopped, just used the highest magnification the i-phone would give me.]
Looking towards Clayhead, something else is wrong – though the i-phone couldn’t capture this picture at all – there is a line of rocks from the base of Clayhead far out to sea, as if Cow Cove (on the other side of the head) had shifted in the night. It is amazing that it could be seen with the eye, which is still better than the camera.
Is that why the boat is coming in head first? From the beach we would always see it broadside on as it runs south to Old Harbor. [It comes from Point Judith, the central dotted line heading north on this map, the other lines are summer boats to Montauk and Newport.]
No, it is not because rocks have mysteriously shifted…
It is a MIRAGE.
So are the rocks.
Seeing is NOT believing, and the camera can lie.
Half an hour later, the boat is where it should be coming ACROSS the bay to the harbor. Don’t need another photo – by then I was on the way home!
On a crisp clear cold day, the air is very much colder than the sea. So there is a layer near the sea where the density of clear air is very different from that a little higher.
The difference in density causes refraction of light – that is, it bends the light rays.
We actually see over the horizon!!!
There is also a magnification effect as well as a bending, so dear old brain decides the boat seen, and the rocks, are looking big, so they must be quite close. The boat in the pictures is actually below the horizon, it has not even reached the Clayhead yet. And the rocks are those on the other side of the head, still where they should be.
A MIRAGE – seeing something not there where it looks as if it is.
And also a miracle, on a beautiful day, made all the better for knowing how this wonderful world works.
To all scientists who forget the “why” is about wonder, do remind yourselves as often as you can.
To all non-scientists, so many artists and writers and creative people who mistakenly think science is technocratic or without soul, just learn what you can of its truthfulness and wonder, let this kind of “how” add its own creative joy to being alive.
And thanks to Judy who can explain all this better than I can as well as keeping me company on walks.