Have you ever enjoyed a good session of skimming stones at the beach?
You know those times when the stone hits the water at the perfect angle and off if flies again. And again and again. Oh, the satisfaction.
But then there are those times when the stone hits the water at too steep an angle. Plunk. It is gone, sunk.
Light behaves in a similar way. It is all about the angle it hits the water.
Notice how, when we look steeply down, we can see down into the water all the way to the tiles at the bottom of the pond. But if we look across the water at a shallow angle, we cannot see into it at all, we only see the reflected sky and stones.
I had not given this effect a name when writing the book, but ‘The Skimming Effect’ seems about right.