Perhaps the most amazing sight for me was on a cold winter flight in Alaska on a helo medivac. I noticed the distant mountains had been transformed from the very familiar shape into somthing that looked like vertical cliffs over 10,000ft high.
I thought maybe I was having a religous experience or going crazy. Finally I asked the pilot next to me what he thought was going on. He had no idea either.
Later I found out it was an atmospheric allusion or mirage called Fata Morgana.
Looks very real.
slowrotor