We all know sunsets can be beautiful, often producing intense colors in the sky, clouds, and reflective surfaces. This web page shows some cool pics of interesting phenomena that can occur with sunsets (and sunrises). All pictures look West over the Gulf of Mexico from the Cedar Key area of Florida November 2018. Equipment used included the Nikon D850 Camera, Nikon 500mm lens, and a lightweight tripod kit including a Gitzo GT2531EX Series 2 Carbon 6x 3 Section G-Lock Explorer Tripod and Acratech GV2 Ballhead. The "green flash" pics are all f8, 1/1250s, and ISO 200 with manual exposure.
Sunset mirages and green flashes result from unusual refraction by air layers at different temperatures and hence density and refractive index. The refractive index differences are minute but their effects accumulate as sunset rays travel large distances through the atmosphere. (Reference) Wikipedia has good info here. It seems temperature gradients in the atmosphere help produce the effects seen.
Green Flashes, Green Rims, below. For a second or two, the Sun’s upper rim can appear intensely green. Although called a “flash,” it's more a vividly green coloration to the first or last blip of the Sun visible at the horizon as explained on this page. Andrew Young also has good references on Green Flashes. I'm not sure that what's shown here is a classic green flash, which is often shown as a detached image above the sun. Here's another good reference for green flashes from EarthSky.
Feel free to write me via email to better explain what's shown if you know!
The above shows a very distorted solar disc with green fringes. Refraction and the mirage effect cause the sun to not appear round.
Four seconds later, the green effect intensifies (above).
This shows the most intense green - visually I saw a more significant flash through the camera between the automated 4 second exposures. So dang, I missed the most intense part with the camera. Going forward I will shoot manually when trying to capture green flashes!
Another 4 seconds later the effect is fading, but still very cool looking.
Above: An earlier shot in the sequence shows a bit of blue; there's also such a thing as a blue flash.
Changing topics a bit, note below the light seeming to reach up from the horizon to touch the sun. This is a mirage. As explained on this page: Sunset mirages, two or more images of the sun, are seen when its low slanting rays are unusually refracted between air layers of different temperature.
Captured in a sequence of sunset picture 4 seconds apart, the above shows a mirage just starting to form.
Above, a larger "false image" of the sun shows between the sun and water. Various birds including pelicans are flying by, lending a nice accent to the pic. This is a only 4 seconds after the top picture - things move quickly as the sun plunges into the Gulf!
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