The Strait of Messina’s Shifting Sea

Loudon said the sea could seem like magic glass, reflecting multiplied castles, towers, avenues, plains, herds, and flocks.

She reported that the forms could appear faintly in the air as well as on the sea.

In slightly hazy air, the reflected forms could be edged with every colour of the rainbow.

Loudon explained the illusion as refraction: warmer surface air became less dense than the cooler air above, bending light back.