Double Sunrise Phenomenon Explanation?

[Cmotive98]

How did you find PF?: Googling about a double sunrise phenomenon, since I have just photographed and videoed one.

I just want to share some photos, and a video, I personally took sitting in the observation deck of a cruise ship between Cabo, San, Lucas, and Ensenada, Mexico, while out at sea. The date was November 11, 2023 at sunrise. I am a retired nurse. I am not a physics expert and I am not currently a student, but I want to share this in case anyone is interested. By the way, this is not a hoax, I visualized this with my own eyes, as well as through the camera lens of my iPhone. I was, however, sitting on an observation deck of a cruise ship behind the windows. Some of the smaller specs of light are reflections from the lights behind me.

 

[pbuk]

I just want to share some photos, and a video

I can't see a video, but I suspect this is caused by an internal reflection, and you were not looking straight through the window at right angles, rather you were looking to your right.

The light from the Sun travels through the glass and when it reaches the inside surface some of it reflects back towards the outside (the glass is treated to make quite a lot of it reflect back outside, particularly towards the red end of the spectrum, to stop the inside of the ship heating up like a greenhouse). When this reflected light reaches the outside surface, again some of it reflects back, this time towards you, and because of the thickness of the glass and the angle you are looking at it, the path of this part of the light follows a zig-zag and it is displaced to the left.

You therefore see a second image of the Sun, dimmer and somewhat redder, to the left of the main image. The phenomenon is similar to Pepper's ghost.

Of course this is only a guess based on the fairly limited information in the pictures: it could be that some other phenomenon is taking place.

 

[Baluncore]

I was, however, sitting on an observation deck of a cruise ship behind the windows. Some of the smaller specs of light are reflections from the lights behind me.

In the double or more Suns case, the windows are vertical on both sides of the ship, but taper towards the end of the vessel. You are in the wedge, between those partially reflective sheets, so you see multiple internal reflections spread along the horizon. That can only happen when the Sun is so low that it also falls on the back wall windows of the wedge space.

My old JCB backhoe has a rear window, that when opened, swings around to lie against the side window, where it forms a wedge from the two sheets of tinted glass. Sunlight passes through the two sheets of glass, then there is an internal reflection that produces an attenuated, but still sharp image, near the first. That continues half a dozen times along the wedge of the windows. The third image can be conveniently viewed by eye to see sunspots. During the transit of Venus, I took a photo of the planet against the Sun. When I looked at the image later, I see a spider's web on the glass. The camera had autofocussed on the glass surface.

Experiment. Get two pieces of tinted glass, make a wedge using different spacers on two sides. View the Sun or a light through both, while playing with the geometry. The order of the multiple images, can be identified by their falling brightness.

 

[Cmotive98]

Thank you so much for this detailed explanation. It makes a lot of sense. I had been thinking it was reflecting off of something in the atmosphere.

 

[diogenesNY]

Another possible explanation, meteorological rather than depending on the windows, is something called a 'sundog' or 'mock sun' usually involving refraction through atmospheric ice crystals.

More here:

https://en.wikipedia.org/wiki/Sun_dog

 

[Baluncore]

Another possible explanation, meteorological rather than depending on the windows, is something called a 'sundog' or 'mock sun' usually involving refraction through atmospheric ice crystals.

That is true.
A sun dog can be identified by, the fixed, very close to 22° angular separation between the Sun and a dog. In the case of the OP pictures, judging by the angular size of the double-reflected Sun's disc, the separation is closer to one tenth of that.

Given the opportunity, investigate closely the optical path involved. There are too many possibilities.
If you view the Sun through a wedge, you should see a fixed image separation, largely independent of incidence angle. If you view the Sun from inside, between the reflectors, you should see an image separation determined by the course dependent incidence angle.
The double reflection may also result from the construction of parallel double glazing on the observation deck. In that case, the image separation would also be course dependent.