APOD: Anticrepuscular Rays Over Colorado (2010 Nov 28)

[montylc2001]

indeed. hhhhmmmm. It will have to wait till summer to get the pics

[neufer]

indeed. hhhhmmmm. It will have to wait till summer to get the pics

1) The shadow of a New Mexico Mountain upon a cloud 100 miles away would be blurred beyond all recognition due to the finite 0.5º width of the sun.

2) The blurred shadow of a New Mexico Mountain would not even reach a cloud 300 miles away due to the curvature of the Earth.

3) Fort Worth is 500 miles away from the New Mexico Mountains.

[montylc2001]

It would seem, Sir, that instead of engaging in a serious discussion concerning a phenomenon that I and others have witnessed over 30 years you would rather belittle others posts in some attempt to show your "superiority". The point I was trying to make was the same pattern occurs during a specific time frame of days each year. It is not weather related for not only does the pattern change over the course of several minutes as would be the case if clouds were causing it, but also during the course of several days the pattern is the same. My conjecture of which geological feature could be causing it was just that, conjecture, but when I determine which I will gladly let you know.

[neufer]

The Flying Saucer Draught Emporium

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It would seem, Sir, that instead of engaging in a serious discussion concerning a phenomenon that I and others have witnessed over 30 years you would rather belittle others posts in some attempt to show your "superiority". The point I was trying to make was the same pattern occurs during a specific time frame of days each year. It is not weather related for not only does the pattern change over the course of several minutes as would be the case if clouds were causing it, but also during the course of several days the pattern is the same. My conjecture of which geological feature could be causing it was just that, conjecture, but when I determine which I will gladly let you know.

Great I hope that you do, monty.

The Flying Saucer Draught Emporium is surrounded by tall buildings.
My conjecture is they may be the source of your Anticrepuscular Rays.

[montylc2001]

The Flying Saucer Draught Emporium

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It would seem, Sir, that instead of engaging in a serious discussion concerning a phenomenon that I and others have witnessed over 30 years you would rather belittle others posts in some attempt to show your "superiority". The point I was trying to make was the same pattern occurs during a specific time frame of days each year. It is not weather related for not only does the pattern change over the course of several minutes as would be the case if clouds were causing it, but also during the course of several days the pattern is the same. My conjecture of which geological feature could be causing it was just that, conjecture, but when I determine which I will gladly let you know.

Great I hope that you do, monty.

The Flying Saucer Draught Emporium is surrounded by tall buildings.
My conjecture is they may be the source of your Anticrepuscular Rays.

Right. Considering downtown Fort Worth is to the east of me your reply not only demonstrates your lack of maturity but also your credibility. I suppose your idea of the scientific method is based on your perception that you are "A legend in my own mind".

[owlice]

Ahem. http://asterisk.apod.com/vie ... 28&t=18054

Rule 4. Please heed. Thank you!

I should think that buildings would be able to create this phenomenon, wouldn't they?

(I'm amused to learn there is a Flying Saucer Draught Emporium; thanks for that!)

[montylc2001]

Ahem. http://asterisk.apod.com/vie ... 28&t=18054

Rule 4. Please heed. Thank you!

I should think that buildings would be able to create this phenomenon, wouldn't they?

(I'm amused to learn there is a Flying Saucer Draught Emporium; thanks for that!)

The Flying Saucer Draught Emporium was closed down several months ago. It was a bar and grill which the owner named after his last job, a dishwasher at a restuarant. He was fired for slinging dishes at the owner, hence the "flying saucer", not UFO's

[owlice]

The Flying Saucer Draught Emporium was closed down several months ago. It was a bar and grill which the owner named after his last job, a dishwasher at a restuarant. He was fired for slinging dishes at the owner, hence the "flying saucer", not UFO's

Well, yes. Who said anything about UFOs??

[Céline Richard]

This picture is so clear and so beautiful , i could imagine this:

Anticrepuscular rays photographed in 2001 from a moving car just outside of Boulder

From a moving car? We can see very well the animals and the landscape. So wonderful !

[RADDAD]

Interesting discussions. Sometimes it is good just to ENJOY the photo or the phenomenon. I first noticed this display while driving in eastern Oregon with my stepson. I stopped the car and we stood there wondering why the rays were reconverging toward the opposite horizon ... They should keep diverging from the point source!! Of course the "point" of origin is NOT a point at all, but a rather significant sphere called the sun. I think the easiest way to understand what is going on is to imagine standing on a railroad track and notice that perspective works in BOTH directions. I found the great circle projection explanation a bit confusing and inaccurate. These are simply straight parallel lines with disappearing points in both directions.

[neufer]

The Flying Saucer Draught Emporium was closed down several months ago. It was a bar and grill which the owner named after his last job, a dishwasher at a restuarant. He was fired for slinging dishes at the owner, hence the "flying saucer", not UFO's

Well, yes. Who said anything about UFOs??

Neil deGrasse Tyson?

Click to play embedded YouTube video.

[owlice]

That's a great video, neufer; thanks for that!

[NoelC]

You have my thanks as well Neufer, for sharing that video link - that was GREAT!

My favorite part: "Photoshop probably has a UFO button"

-Noel

[Céline Richard]

Interesting discussions. Sometimes it is good just to ENJOY the photo or the phenomenon.

I understand, i like when a picture makes me dreaming too!!
I come to enjoy, but then... i have to admit that curiosity is something difficult to make vanishing.

Céline

[sea otter]

My favourite part, in neufer's posted material, is when Neil deGrasse Tyson says "Its' all bad because we're human".

[Jahdirt]

Can anyone explain why "Great Circles" are mentioned in a photo of crepuscular/anticrepuscular rays?

The rays appearance is from perspective, and has nothing to do with the spherical nature of Earth, correct?

Why does the caption say that sun rays, when "projected on the Earth atmosphere, are Great Circles" when they are still just essentially parallel beams of light?

The explanation that they are Great Circles implies that they are curving with the Earth surface/atmosphere, which is a minor effect -- certainly not a Great Circle -- and not one that contributes to this phenomenon.

Can't crepuscular and anticrepuscular rays appear anywhere in space regardless of whether or not Earth is present?

[Jahdirt]

And when I say the "curving with the Earth or the atmosphee" is a minor effect, I only mean of course the refraction that happens when light enters the atmosphere from space. Obviously there is no curving of light beams with the surface of the earth, unless absolutely fractionally from gravitational lensing.

I am totally stumped as to why Great Circles are mentioned in the caption but there they are. These light beams are essentially as straight and parallel as if they were traveling through open space.

cheers
j

[neufer]

Anticrepuscular Rays Over Colorado

[b][color=#0000FF]Crepuscular rays as seen from the International Space Station[/color][/b]

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<<The sight of shafts of light streaming down from the heavens through a layer of clouds has provided many an artist, scientist, and philosopher with inspiration. Atmospheric scientists refer to this phenomenon as “crepuscular rays,” referring to the typical observation times at either sunrise or sunset. The shadowed areas bounding the rays are formed by clouds or mountain tops that block the path of sunlight or moonlight. However, obstructions alone are not sufficient to create crepuscular rays. The light also must be scattered by airborne dust, aerosols, water droplets, or molecules of air, providing a visible contrast between shadowed and illuminated parts of the sky. When observed from the ground, crepuscular rays appear to radiate outwards from the source of light due to the effects of distance and perspective. However, the rays are actually parallel. This astronaut photograph from the International Space Station provides an unusual viewing perspective from above the rays and a clear illustration of their parallel nature. The sun was setting to the west (image left) on the Indian subcontinent, and cumulonimbus cloud towers provided the shadowing obstructions. The rays are being projected onto a layer of haze below the clouds.