Have you heard of the mirage effect on the sea?

[Timothy Schablin]

I remember reading about how a city could be seen across a sea at certain times. But normally would not be seen because of Earth's curvature. At certain times however, it could be seen because of light bending. I can't remember what the cause was though.

Anyone know about this and what caused it?

 

[Janus]

There is always some refraction due to the atmosphere that causes light to bend in its path and allows you to see a bit beyond the physical horizon. This effect can be increased when there is a temperature gradient in the air, such as when warm air is sitting over a cool body of water. In these cases the distance you can see past the horizon becomes further than it would under normal conditions.

 

[Charles Link]

It might be of interest that the sun is already geometrically set, just about the time when it appears to start to set.

 

[anorlunda]

The word for what the otters described is mirage. Read more here https://en.m.wikipedia.org/wiki/Mirage