exchemist
Veteran Member
The picture in this link is quite is quite striking; an oil tanker apparently floating in the sky: Walker 'stunned' to see ship hovering high above sea off Cornwall
It is caused by a "superior mirage", which is fairly rare, though it sometimes can be seen at the shores of the Great Lakes in N America, I understand.
Normally the air closest to the surface is warmer than the air above. But when there is a temperature "inversion", you get the air closest to the surface cooler than the air above. Cooler air is denser and light travels through it a tiny bit more slowly than in the warmer air above, causing light rays to curve downward very slightly as they pass through over long enough distances. Your eye, however, assumes the light entering it from a distant object has travelled in a straight line. The result is that it sees the object higher than it really is.
No doubt in medieval times this would be considered miraculous - not that they had oil tankers then.......
It is caused by a "superior mirage", which is fairly rare, though it sometimes can be seen at the shores of the Great Lakes in N America, I understand.
Normally the air closest to the surface is warmer than the air above. But when there is a temperature "inversion", you get the air closest to the surface cooler than the air above. Cooler air is denser and light travels through it a tiny bit more slowly than in the warmer air above, causing light rays to curve downward very slightly as they pass through over long enough distances. Your eye, however, assumes the light entering it from a distant object has travelled in a straight line. The result is that it sees the object higher than it really is.
No doubt in medieval times this would be considered miraculous - not that they had oil tankers then.......