APOD: Glory and Fog Bow (2024 Aug 03)

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APOD: Glory and Fog Bow (2024 Aug 03)

Post by APOD Robot » Sat Aug 03, 2024 4:06 am

Image Glory and Fog Bow

Explanation: On a road trip up Mount Uludağ in Bursa province, Turkey these motorcyclists found themselves above low clouds and fog in late June. With the bright Sun directly behind them, the view down the side of the great mountain revealed a beautiful, atmospheric glory and fog bow. Known to some as the heiligenschein or the Specter of the Brocken, a glory can also sometimes be seen from airplanes or even high buildings. It often appears to be a dark giant surrounded by a bright halo. Of course the dark giant is just the shadow of the observer (90MB video) cast opposite the Sun. The clouds and fog are composed of very small water droplets, smaller than rain drops, that refract and reflect sunlight to create the glory's colorful halo and this more extensive fog bow.

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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by Holger Nielsen » Sat Aug 03, 2024 9:29 am

Is that really a fog bow? To me it looks just as some background clouds.
Below is an image of a fogbow photographed in the Greenland Sea in September 2023. "Fun fact" about glories: If you see a glory and are acompagnied by other people, you will only see a glory around your own head.
2023 09 19 14 14 05 Grøndlandshavet Tågebue Montage.jpg

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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by gmPhil » Sat Aug 03, 2024 11:39 am

Holger Nielsen wrote: Sat Aug 03, 2024 9:29 am "Fun fact" about glories: If you see a glory and are acompagnied by other people, you will only see a glory around your own head.
That would imply that the the one seen in this pic is that of the photographer, not the motorcyclist in the photo... is that the case?

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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by Chris Peterson » Sat Aug 03, 2024 12:00 pm

gmPhil wrote: Sat Aug 03, 2024 11:39 am
Holger Nielsen wrote: Sat Aug 03, 2024 9:29 am "Fun fact" about glories: If you see a glory and are acompagnied by other people, you will only see a glory around your own head.
That would imply that the the one seen in this pic is that of the photographer, not the motorcyclist in the photo... is that the case?
Yes. You can't see or image somebody else's glory.
Chris

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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by johnnydeep » Sat Aug 03, 2024 5:01 pm

Chris Peterson wrote: Sat Aug 03, 2024 12:00 pm
gmPhil wrote: Sat Aug 03, 2024 11:39 am
Holger Nielsen wrote: Sat Aug 03, 2024 9:29 am "Fun fact" about glories: If you see a glory and are acompagnied by other people, you will only see a glory around your own head.
That would imply that the the one seen in this pic is that of the photographer, not the motorcyclist in the photo... is that the case?
Yes. You can't see or image somebody else's glory.
That makes no sense to me. Why? But I assume if the "glory" is caused by the shadow of another object that you - and others - are inside (like an airplane), then everyone sees the same exact glory, no? And of course, if you and your buddy are side by side, and in actual contact, you would both see the same exact - or close enough - glory, right?
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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by Chris Peterson » Sat Aug 03, 2024 5:09 pm

johnnydeep wrote: Sat Aug 03, 2024 5:01 pm
Chris Peterson wrote: Sat Aug 03, 2024 12:00 pm
gmPhil wrote: Sat Aug 03, 2024 11:39 am
That would imply that the the one seen in this pic is that of the photographer, not the motorcyclist in the photo... is that the case?
Yes. You can't see or image somebody else's glory.
That makes no sense to me. Why? But I assume if the "glory" is caused by the shadow of another object that you - and others - are inside (like an airplane), then everyone sees the same exact glory, no? And of course, if you and your buddy are side by side, and in actual contact, you would both see the same exact - or close enough - glory, right?
It's not a shadow being cast on a plane, but a column of darker air extending directly away from the viewer towards the anti-solar point. You don't have to go very far off-axis until there's simply no longer enough contrast to see the glory. Of course, if someone has their head up against yours, you'll both see very close to the same thing (but not exactly). The shadow we see in today's APOD is substantially from the imager, not the guy with his hand up.
Chris

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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by johnnydeep » Sat Aug 03, 2024 5:15 pm

Chris Peterson wrote: Sat Aug 03, 2024 5:09 pm
johnnydeep wrote: Sat Aug 03, 2024 5:01 pm
Chris Peterson wrote: Sat Aug 03, 2024 12:00 pm

Yes. You can't see or image somebody else's glory.
That makes no sense to me. Why? But I assume if the "glory" is caused by the shadow of another object that you - and others - are inside (like an airplane), then everyone sees the same exact glory, no? And of course, if you and your buddy are side by side, and in actual contact, you would both see the same exact - or close enough - glory, right?
It's not a shadow being cast on a plane, but a column of darker air extending directly away from the viewer towards the anti-solar point. You don't have to go very far off-axis until there's simply no longer enough contrast to see the glory. Of course, if someone has their head up against yours, you'll both see very close to the same thing (but not exactly). The shadow we see in today's APOD is substantially from the imager, not the guy with his hand up.
Alright. There's that "column of darker air" as opposed to a "shadow" distinction again. The text refers to cast shadows - the "shadow of the observer" - so that's what I was regurgitating. And I assume you meant "cast by a plane" not "cast on a plane".
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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by Chris Peterson » Sat Aug 03, 2024 5:17 pm

johnnydeep wrote: Sat Aug 03, 2024 5:15 pm
Chris Peterson wrote: Sat Aug 03, 2024 5:09 pm
johnnydeep wrote: Sat Aug 03, 2024 5:01 pm

That makes no sense to me. Why? But I assume if the "glory" is caused by the shadow of another object that you - and others - are inside (like an airplane), then everyone sees the same exact glory, no? And of course, if you and your buddy are side by side, and in actual contact, you would both see the same exact - or close enough - glory, right?
It's not a shadow being cast on a plane, but a column of darker air extending directly away from the viewer towards the anti-solar point. You don't have to go very far off-axis until there's simply no longer enough contrast to see the glory. Of course, if someone has their head up against yours, you'll both see very close to the same thing (but not exactly). The shadow we see in today's APOD is substantially from the imager, not the guy with his hand up.
Alright. There's that "column of darker air" as opposed to a "shadow" distinction again. The text refers to cast shadows - the "shadow of the observer" - , so that's what I was regurgitating. And I assume you meant "cast by a plane" not "cast on a plane".
No, I meant cast on a plane. Like a normal shadow. Anybody looking at that planar surface will see the same shadows, no matter where they're viewing it from. But in this case all that we're seeing is a column with reduced scatter. That's only going to be apparent when you're looking along that column, not across it.
Chris

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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by johnnydeep » Sat Aug 03, 2024 5:28 pm

Chris Peterson wrote: Sat Aug 03, 2024 5:17 pm
johnnydeep wrote: Sat Aug 03, 2024 5:15 pm
Chris Peterson wrote: Sat Aug 03, 2024 5:09 pm
It's not a shadow being cast on a plane, but a column of darker air extending directly away from the viewer towards the anti-solar point. You don't have to go very far off-axis until there's simply no longer enough contrast to see the glory. Of course, if someone has their head up against yours, you'll both see very close to the same thing (but not exactly). The shadow we see in today's APOD is substantially from the imager, not the guy with his hand up.
Alright. There's that "column of darker air" as opposed to a "shadow" distinction again. The text refers to cast shadows - the "shadow of the observer" - , so that's what I was regurgitating. And I assume you meant "cast by a plane" not "cast on a plane".
No, I meant cast on a plane. Like a normal shadow. Anybody looking at that planar surface will see the same shadows, no matter where they're viewing it from. But in this case all that we're seeing is a column with reduced scatter. That's only going to be apparent when you're looking along that column, not across it.
Gah! So is it always wrong to say that an object casts a shadow on something else, which shadow is cast by that object?
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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by Chris Peterson » Sat Aug 03, 2024 5:41 pm

johnnydeep wrote: Sat Aug 03, 2024 5:28 pm
Chris Peterson wrote: Sat Aug 03, 2024 5:17 pm
johnnydeep wrote: Sat Aug 03, 2024 5:15 pm

Alright. There's that "column of darker air" as opposed to a "shadow" distinction again. The text refers to cast shadows - the "shadow of the observer" - , so that's what I was regurgitating. And I assume you meant "cast by a plane" not "cast on a plane".
No, I meant cast on a plane. Like a normal shadow. Anybody looking at that planar surface will see the same shadows, no matter where they're viewing it from. But in this case all that we're seeing is a column with reduced scatter. That's only going to be apparent when you're looking along that column, not across it.
Gah! So is it always wrong to say that an object casts a shadow on something else, which shadow is cast by that object?
Well, when we talk about shadows we're usually referring to them on some surface. But we also talk about things being shadowed, right? In this case, the air column that is blocked by the viewer is being shadowed. I guess it's just how we use the word in context. And we talk about being in something's shadow, too. Like a cloud. We don't necessarily see anything other than a reduction in the light around us.
Chris

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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by johnnydeep » Sat Aug 03, 2024 6:17 pm

Chris Peterson wrote: Sat Aug 03, 2024 5:41 pm
johnnydeep wrote: Sat Aug 03, 2024 5:28 pm
Chris Peterson wrote: Sat Aug 03, 2024 5:17 pm
No, I meant cast on a plane. Like a normal shadow. Anybody looking at that planar surface will see the same shadows, no matter where they're viewing it from. But in this case all that we're seeing is a column with reduced scatter. That's only going to be apparent when you're looking along that column, not across it.
Gah! So is it always wrong to say that an object casts a shadow on something else, which shadow is cast by that object?
Well, when we talk about shadows we're usually referring to them on some surface. But we also talk about things being shadowed, right? In this case, the air column that is blocked by the viewer is being shadowed. I guess it's just how we use the word in context. And we talk about being in something's shadow, too. Like a cloud. We don't necessarily see anything other than a reduction in the light around us.
Ok. So then it's correct to think of the object "casting" the "shadow" (column of darker air) "onto" something else that happens to intersect the path of that column. No?
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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by Holger Nielsen » Sat Aug 03, 2024 6:54 pm

As has been explained the glory is not a particular object in the sky, but the effect of backscattering of light rays from the sun from a particular set of raindrops in the sky in front and below you. The same can be said about the rainbow: Every person observes their own rainbow produced by reflection and refraction from a particular set of almost spherical raindrops in front of you.

Here is an experiment you can make on a clear day: Put on your bathing suit and take a water hose outside. Open the water, hold the hose vertically slightly away from yourself (in order not to get drenched). Now squeeze the hose end to produce a spray of water droplets. You should now see a complete 360º rainbow in front of you. And if you place your face close to the hose you will see two almost overlapping rainbows, one with each eye!

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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by Chris Peterson » Sat Aug 03, 2024 7:03 pm

Holger Nielsen wrote: Sat Aug 03, 2024 6:54 pm As has been explained the glory is not a particular object in the sky, but the effect of backscattering of light rays from the sun from a particular set of raindrops in the sky in front and below you. The same can be said about the rainbow: Every person observes their own rainbow produced by reflection and refraction from a particular set of almost spherical raindrops in front of you.

Here is an experiment you can make on a clear day: Put on your bathing suit and take a water hose outside. Open the water, hold the hose vertically slightly away from yourself (in order not to get drenched). Now squeeze the hose end to produce a spray of water droplets. You should now see a complete 360º rainbow in front of you. And if you place your face close to the hose you will see two almost overlapping rainbows, one with each eye!
Don't wear a bathing suit! You need a hazmat suit to do this experiment!
.
Click to play embedded YouTube video.
Chris

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Re: APOD: Glory and Fog Bow (2024 Aug 03)

Post by NateWhilk » Sat Aug 03, 2024 9:15 pm

Chris Peterson wrote: Sat Aug 03, 2024 7:03 pm Don't wear a bathing suit! You need a hazmat suit to do this experiment!
OMG! :shock: :lol2:

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