APOD: Red Cloudbow over Delaware (2018 Jun 13)

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APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by APOD Robot » Wed Jun 13, 2018 4:05 am

Image Red Cloudbow over Delaware

Explanation: What kind of rainbow is this? In this case, no rain was involved -- what is pictured is actually a red cloudbow. The unusual sky arc was spotted last month during sunset in Rehoboth Beach, Delaware, USA. When the photographer realized that what he was seeing was extraordinary, he captured it with the only camera available -- a cell phone. Clouds are made of water droplets, and in a cloudbow a cloud-droplet group reflects back light from the bright Sun (or Moon) on the opposite side of the sky. Similar phenomena include fogbows and airplane glories. Here, the red color was caused by atmospheric air preferentially scattering away blue light -- which simultaneously makes most of the sky appear blue. A careful inspection reveals a supernumery bow just inside the outermost arc, a bow caused by quantum diffraction.

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by Boomer12k » Wed Jun 13, 2018 8:00 am

Nice Shot...very interesting phenomena, i was not acquainted with it...
I see a lot of yellow, and some green at the bottom of the bow too...

Going to need a plane to get the two pots of GOLD...
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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by Ann » Wed Jun 13, 2018 10:00 am

Really interesting. You can clearly see that where the cloud ends, the cloudbow stops abruptly, too.

Another way of putting it is, perhaps, to say that this is yet another variety of an Earthly nebula!

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by Indigo_Sunrise » Wed Jun 13, 2018 10:47 am

This is a very intriguing image; I'd never heard of this before either. I'd love to capture an image like this! 8-)


(oh, and Boomer, can we share the pots of gold? One for you and one for me? :mrgreen: )
Forget the box, just get outside.

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by TomTrzicky » Wed Jun 13, 2018 10:51 am

Nice shot. Just curious,which cell phone covers aprox. 90° field of view?

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by orin stepanek » Wed Jun 13, 2018 11:48 am

Nice! 8-)
Orin

Smile today; tomorrow's another day!

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by gmPhil » Wed Jun 13, 2018 12:55 pm

But... why is the sea-horizon not flat?! ( I don't mean horizontal - that's just the way the camera was held - but it isn't straight.)

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by Chris Peterson » Wed Jun 13, 2018 1:05 pm

gmPhil wrote:
Wed Jun 13, 2018 12:55 pm
But... why is the sea-horizon not flat?! ( I don't mean horizontal - that's just the way the camera was held - but it isn't straight.)
Because the camera is essentially imaging the inside of a sphere (the sky). You can't squeeze a spherical surface onto a plane without distortion. That's why all maps display some kind of distortion. Look at any good lens review, and they'll make a test image of a grid so you can see the pincushion, barrel, and other types of distortion.

In this case, had the horizon been level and vertically centered, it likely would have appeared straight.
Chris

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Sa Ji Tario

Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by Sa Ji Tario » Wed Jun 13, 2018 1:13 pm

I prefer it with Bitcoins and not gold

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by gmPhil » Wed Jun 13, 2018 1:17 pm

OK.... but then so are my eyes when I look at the sea, and it looks flat.... are you saying that any image of the sea will, unless the camera is held dead upright, will display the horizon in a similar way? I'm going on Google images to look.....

...[later] ok, you win! :) Mind you, it's (surprisingly?) not easy to find images of the sea where the horizon is not horizontal.... (kind of tautological, innit?!)

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by Sensa Wunda » Wed Jun 13, 2018 1:30 pm

Wait a sec. The supernumerary bow is not a quantum phenomenon, merely a wave diffraction phenomenon.

And y'all might want to spell it "supernumerary" rather than "supernumery".

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by Chris Peterson » Wed Jun 13, 2018 2:15 pm

gmPhil wrote:
Wed Jun 13, 2018 1:17 pm
OK.... but then so are my eyes when I look at the sea, and it looks flat.... are you saying that any image of the sea will, unless the camera is held dead upright, will display the horizon in a similar way? I'm going on Google images to look.....

...[later] ok, you win! :) Mind you, it's (surprisingly?) not easy to find images of the sea where the horizon is not horizontal.... (kind of tautological, innit?!)
It happens with your eyes, too. But your brain does a good job of removing the distortion and fooling you. But if you pay very close attention, you can work around that and see the true shape of the image in your eye. (Optically, the effect is weaker in the eye because the retina isn't a planar surface. Curved focal planes do wonders for removing distortion. There are old astronomical telescopes, like the 48" Schmidt at Palomar, that sucked film onto a curved surface to reduce distortion.)
Chris

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by neufer » Wed Jun 13, 2018 2:16 pm

Chris Peterson wrote:
Wed Jun 13, 2018 1:05 pm
gmPhil wrote:
Wed Jun 13, 2018 12:55 pm

But... why is the sea-horizon not flat?! ( I don't mean horizontal - that's just the way the camera was held - but it isn't straight.)
Because the camera is essentially imaging the inside of a sphere (the sky). You can't squeeze a spherical surface onto a plane without distortion. That's why all maps display some kind of distortion. Look at any good lens review, and they'll make a test image of a grid so you can see the pincushion, barrel, and other types of distortion.

In this case, had the horizon been level and vertically centered, it likely would have appeared straight.
Which brings us back to Tom Trzicky's query:
TomTrzicky wrote:
Wed Jun 13, 2018 10:51 am

Just curious,which cell phone covers aprox. 90° field of view?
Art Neuendorffer

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by neufer » Wed Jun 13, 2018 2:23 pm

Sensa Wunda wrote:
Wed Jun 13, 2018 1:30 pm

Wait a sec. The supernumerary bow is not a quantum phenomenon, merely a wave diffraction phenomenon.

And y'all might want to spell it "supernumerary" rather than "supernumery".
The supernumerary bow is a quantum phenomenon if light
is recognized to consist of particles following ray trajectories.
Art Neuendorffer

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by E Fish » Thu Jun 14, 2018 3:54 am

I have to say that I've been following the APOD for many years now, never missing a day (or almost never), and I never had noticed the discussion link before. I'm glad I have because I feel like I get smarter every time I come here and read more about these photos. :)

Lil Stinker

Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by Lil Stinker » Thu Jun 14, 2018 5:33 pm

neufer wrote:
Wed Jun 13, 2018 2:16 pm
Chris Peterson wrote:
Wed Jun 13, 2018 1:05 pm
gmPhil wrote:
Wed Jun 13, 2018 12:55 pm

But... why is the sea-horizon not flat?! ( I don't mean horizontal - that's just the way the camera was held - but it isn't straight.)
Because the camera is essentially imaging the inside of a sphere (the sky). You can't squeeze a spherical surface onto a plane without distortion. That's why all maps display some kind of distortion. Look at any good lens review, and they'll make a test image of a grid so you can see the pincushion, barrel, and other types of distortion.

In this case, had the horizon been level and vertically centered, it likely would have appeared straight.
Which brings us back to Tom Trzicky's query:
TomTrzicky wrote:
Wed Jun 13, 2018 10:51 am

Just curious,which cell phone covers aprox. 90° field of view?
From the artist's website:
CAMERA LG VS988
ISO 100
FOCAL LENGTH 2.0 mm (2.0 mm in 35mm)
APERTURE f/2.4
EXPOSURE TIME 0.025s (1/40)
NAME Cloudbow.jpg
SIZE 4160 x 3120
DATE TAKEN 2018-05-19 20:06:06
DATE MODIFIED 2018-06-13 12:12:17
LATITUDE 38.72173
LONGITUDE -75.07623
Advanced
CITY Rehoboth Beach
STATE Delaware
COUNTRY United States
COUNTRY CODE US
FLASH Off, Did not fire
METERING Center-weighted average
EXPOSURE PROGRAM Not Defined
EXPOSURE MODE Auto
WHITE BALANCE Auto
DIGITAL ZOOM RATIO 1
SENSING METHOD One-chip color area

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Re: APOD: Red Cloudbow over Delaware (2018 Jun 13)

Post by Chris Peterson » Thu Jun 14, 2018 6:20 pm

Lil Stinker wrote:
Thu Jun 14, 2018 5:33 pm
TomTrzicky wrote:
Wed Jun 13, 2018 10:51 am

Just curious,which cell phone covers aprox. 90° field of view?
From the artist's website:
CAMERA LG VS988
ISO 100
FOCAL LENGTH 2.0 mm (2.0 mm in 35mm)
APERTURE f/2.4
EXPOSURE TIME 0.025s (1/40)
NAME Cloudbow.jpg
SIZE 4160 x 3120
DATE TAKEN 2018-05-19 20:06:06
DATE MODIFIED 2018-06-13 12:12:17
LATITUDE 38.72173
LONGITUDE -75.07623
To be more clear, this phone has two cameras, and the f/2.4 one has a 125° FOV. That's consistent with the approximately 100° FOV in this image (presumably cropped from the original).
Chris

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