Atmospheric Effects aka Heat Waves

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This topic comes up fairly frequently. Most people think it is only an issue when shooting across a hot surface. However it can occur at any temperature. The phenomenon is not caused by high temperatures but rather by temperature differences in the air. The overall temperature can be quite cold and thermal effects can still occur.

This morning while enjoying my morning coffee I noticed that there was an extreme amount of atmospheric distortion in our view of the valley/inlet. In the valley below( image no.2) it was 21F(-6C) and calm. At our house it was 29F(-2C) with 20-30mph wind. The temperature inversion was due to the warm "chinook" wind blowing down the mountain.

The white at bottom of frame in image no.2 is a frozen lake with a couple of feet of snow covering it. Also it was early morning and heavily overcast. So the distortion is certainly not due to heat rising from the surface. The difference in conditions caused a layer of turbulent air of variable temperature/density between the camera and the subject. That is the cause of the "heat wave" effect. Without the wind/turbulence a temperature inversion like this can cause distortion but it manifests itself as a shift in apparent position or stretching of the distant object rather than the wavy effect. That phenomenon is known as "fata morgana" as seen in image no.3.

D850(DX mode), 500mm PF, 1/1000s f8 ISO800, handheld, images received exactly the same minimal PP/crop in LR, only sharpening was during export to jpeg

1) Focused on spruce tree about 200 ft from camera.
p2308853548-5.jpg
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2) Focused on the house about a mile distant and several hundred feet lower elevation.
p2308853562-5.jpg
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3) Fata Morgana effect on distant mountains shot on a calm, extremely cold day.
p4101388415-6.jpg
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Commodorefirst

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And it can be particularly bad across open water, and a plowed field too. Great demonstration images.
 

F64

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When we lived on Lake Erie, there were often inversions on the horizon that actually reflected images of lake freighters that were over the horizon - upside down in the air above the lake. I didn't have any telephotos in those days, so I was never able to get a good picture of the phenomenon.
It was a great location for lightning photos - and once I saw ball lightning - but of course, missed the shot.
 
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Normal refraction also means you can see beyond the horizon. If I remember right it's 14" of arc per kilometre the light bends, on average.
 

F64

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Normal refraction also means you can see beyond the horizon. If I remember right it's 14" of arc per kilometre the light bends, on average.
Yes - but I couldn't explain how the ships would appear upside down unless there was an inversion that reflected the over the horizon image like a mirage on hot pavement.
 

F64

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If they were so far away, how do you know they weren't upside down? :p
Ha! You got me there. They were right side up as they steamed west across Lake Erie in front of me until they disappeared over the horizon and then popped up in the air above the water upside down. And no, I don't drink LOL. We lived in Southwestern Ontario right across from the Enrico Fermi nuclear generating station.
 

Growltiger

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It's called a "superior mirage" when you get a ship floating in the sky. They can be the right way up or upside down. Scroll down to that heading:
https://en.wikipedia.org/wiki/Mirage

Here are two recent ones seen here in England in March this year:
1620029426490.png
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1620029542823.png
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kilofoxtrott

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