Smoke-Filtered Sun
Taken by Helio C. Vital on October 19, 2017 @
Saquarema, Brazil
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Camera Used: Unavailable Unavailable
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Date Taken: Unavailable
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Details:
While hoping to photograph the sunset, I suddenly realized that a dense plume of smoke, produced
by a fire in the woods about 4 km away to the west, was about to totally obstruct the view of
that part of the horizon as a strong and gusty wind was blowing the plume south towards the sea. I then recorded a 4-minute long video of the Sun as its image was being filtered by the plume. Surprisingly it revealed an amazingly rich and dynamic display of colors and shapes across its disk created by a multitude of filtering layers of smoke of varying thickness some 12 minutes before it set. Our first contribution is a still image that shows a multicolored sun. The second item is an animation that displays 9 patterns of colors across the Sun`s disk retrieved from the video. The following color pattern (and estimated degree of filtering) was observed as the Sun`s disk was progressively eclipsed by the smoke: yellow (insignificant change, usual color), orange (light degree of filtering) or vivid red (intermediate), magenta
(intermediate), dark red (severe), brown (extreme). The very interesting magenta color signals the presence of a blue component, possibly due to the
interaction of sunlight with very small aerosols that predominantely scatter red light out of the light path. The main red light component would then combine with that mostly red-free or bluish component, yielding the magenta Sun shown in various images. As the optical path grew thicker the bluish component was also attenuated and the transmitted beam became dark red.
The third item is an animation that includes the most important features noticed in the video.
The findings from the video include the following events in the order: (1) the smoke plume produced by burning of dry vegetation, (2) an aircraft passing in front of the Sun`s disk, the angular size of the moving spot being consistent with the 80 km distance to Rio, (3) a mirror image of the Sun located above it, resembling a second Sun (maybe a kind of parhelium), (4) deformation of the Sun`s disk in many moments, culminating with a
figure akin to an omega Sun below its mirror image,(5) differential refraction, causing the top cap of the magenta Sun to partially detach from the rest of the disk, (6) The fast-changing colors of the "chameleon Sun" with its edge turned fuzzy (bright red contour)
Finally, images of the most interesting phenomena shown in the animations are presented as the fourth contribution as a combination of photos. Note that the presence of distant cirrus formations near the horizon may also have impacted the present findings considerably. A Sony Cyber-Shot DSC-HX300 camera was used to film the Sun passing through the smoke plume between 18:42 and 18:46 (UTC-2h). Frames were retrieved from the video and processed by using the MPC-HC and PhotoScape programs,respectively.
Photographer's website:
No URL provided.
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