Talk:Crepuscular rays

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Physics (Rated Start-class, Mid-importance)
WikiProject icon This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 Mid  This article has been rated as Mid-importance on the project's importance scale.
 

"Jacob's Ladder"?[edit]

Just wondering; in the "Three main forms of crepuscular rays," we have a link to the disambiguation page of Jacob's Ladder (under the first bullet). Since the "Jacob's Ladder" reference in the article doesn't clearly refer to any particular meaning of the term, should it instead be linked to Jacob's Ladder (Bible), with "Jacob's Ladder" (in Crepuscular rays) changed to "also known as Jacob's Ladder? That is, assuming that it indeed is referring to Jacob's Ladder (Bible), going by articles like this. Thanks! ^^ Weien 05:26, 24 January 2006 (UTC)

Unless anyone protests, I've changed it for now. Let me know if I've gone off track here ^^. Weien 06:19, 28 January 2006 (UTC)
I might as well post this here, since it has to do with another name of crepuscular rays . . . another common name is "Angel rays." I believe it was in a movie, and if you search for images on the Internet titled just that, you'll come up with crepuscular rays. Just wondering if anyone can find a solid source with this name so it can be included in that list. Venku Tur'Mukan (talk) 16:14, 24 May 2010 (UTC)

Beams of light diverging from behind a cloud[edit]

Does this contradict the point about linear perspective? Modify 06:22, 18 April 2006 (UTC)

Nope, the sun is behind the cloud and thats where the rays are diverging from. From the perspective viewpoint it is almost the same whether the rays were diverging from the cloud or the sun, both are far away. --Dschwen 07:29, 18 April 2006 (UTC)
Well then, shouldn't you say that "crepuscular rays are almost parallel"? Reading the text as it stands now (and especially the text on today's featured picture) sounds like a blunt mistake, since all rays originate from the sun and therefore they are not parallel. --Zvika 12:46, 18 April 2006 (UTC)
Well, that's what I'd call nitpicking ;-). Sunlight is generally considered parallel in good approximation (to almost precisely 1°). --Dschwen 13:35, 18 April 2006 (UTC)
Sunlight is so close to being parallel that the difference in angle from one side of the earth to the the other is only about 0.0045 degrees. Mikeeg555 12:56, 24 April 2007 (UTC)
I was taking the angular diameter of the sun as seen from earth, which accounts for the statistical directional distribution of sun rays. You are referring to the directional impact of the earth's diameter which is irrelevant for the local phenomenon of crepuscular rays. --Dschwen 13:41, 24 April 2007 (UTC)

Factually incorrect[edit]

'Crepuscular' means 'relating to twilight'. Crepuscular rays are specifically those seen radiating from the horizon after the sun has set or just before it has risen. Sunbeams from behind clouds are a different thing. 85.210.51.88 19:09, 21 August 2006 (UTC)

Yes, but crpuscular rays are actually not that. There are several terms for the different things that fall under the category for what you mention. — [Mac Davis] (talk) (Desk|Help me improve)
I don't think you understand what I'm saying. There are several terms for different types of sunbeam, but the word 'crepuscular' only refers to sunbeams radiating from below the horizon before dawn or after sunset. The word 'crepuscular' comes from latin 'crepusculum' which means twilight. The article currently implies that any sunbeams from behind clouds are crepuscular rays, and has photos of things that are not crepuscular rays. 85.210.51.88 10:52, 30 August 2006 (UTC)
You're going to have to provide a citation beyond the etymology. Phrases often mean more than the words' original meanings. These rays are called this very often. I removed the cleanup tag.—Ben Brockert (42) 05:01, 6 September 2006 (UTC)

Correct[edit]

This article seems correct. All other sources, available in the internet, including those from meterologists, use the Crepuscular rays exactly as this article describes.

You sound surprised! :p — riana_dzasta wreak havoc-damage report 14:58, 12 October 2006 (UTC)

Explanation[edit]

I've always thought crepuscular rays were explained by the Tyndall effect -- am I wrong, or is that something we should mention? 70.17.207.240 20:03, 24 April 2007 (UTC)

I'm not familiar with the nomenclature, but the Tyndall effect according to Wikipedia has more to do with the light-scattering process itself, and chromatic effects that may give coloured-tints, than the apparent ray geometry.

You are correct in the sense that the Tyndall effect is what allows you to see the effect. For example, the Tyndall effect explains how you can see a car's headlights in the fog, but you would not call the beams themselves "The Tyndall effect". Maybe I'm stating the obvious here, anyway, my point is that this article is more about naming a particular phenomenon than explaining it. Jawshoeaw 04:59, 16 October 2007 (UTC)jawshoeaw

I think the defining feature of the rays as described ("Crepuscular rays") in this article is their apparent (false) geometry. They appear to significantly diverge from the source (owing to the viewing angle and perspective effects) the when in reality the light is for all practical purposes parallel. The article notes that the rays are typically seen at the ends of the day, "when the contrasts between light and dark are the most obvious". However I would imagine that the sun needs to be fairly low in the sky in order to create the most dramatic perspective effects too. 57.66.65.38 14:51, 4 July 2007 (UTC) Andrew http://www.techmind.org/

Image pruning[edit]

This article has far too many images for its length! I've restored the two Featured Pictures to their appropriate place of prominence at the head of the article, and removed the following:

I wouldn't normally add insult to injury by offering criticism of images I remove from an article, but there has been a lot of reverting of image inclusion / removal in this article in the last few weeks, and a user requested in an edit summary that an explanation be left here for further amendments. The primary reason for removing some images is the fact that the article had too many, and most were superfluous, but the specific reasons for choosing these to remove are as above. ~ VeledanT 23:54, 21 August 2007 (UTC)

      • Well, they all represent different types of rays. All sky Rays.jpg represents the most visible rays. The image subject is crepuscular rays. So far it is the best picture to represent the article in my opinion. The image 64px shows very, very unique rays with only one picture at Wikipedia and maybe 2-3 other on the whole NET.--Mbz1 04:00, 22 August 2007 (UTC)Mbz1
      • Please do not remove the images. Let people see them to discuss. The images you removed represent the subject in compeling way. It is not you decktop, it is not fp nomination, it is not a quality image nomination, it is encyclopedia. A value of the image is much more important than the quality and btw the quality is very good too. --Mbz1 01:41, 22 August 2007 (UTC)Mbz1
        • I'm with Veledan on this. Mbz1, it is you who are not discussing things before adding images. As Veledan said the article has too many images. And as has already been explained to you, Image:All sky Rays.jpg is too low quality to be part of the images on the article. Feel free to add it to the commons gallery, but it doesn't have a place in the article IMO. However I agree that tho low quality File:Artificial crepuscular rays in San Francisco.jpg (what's with the name?) is quite unique. I think Image:Crepuscular rays 001.jpg can be removed in its favour (it's quite overexposed/not that special). So I would propose the images to look like this (in this order) Crepuscular rays color.jpg Crepuscular ray sunset from telstra tower edit.jpg Beach crepuscular rays.JPG 70px --Fir0002 06:37, 22 August 2007 (UTC)
          • I hope you would agree yhat I cannot discuss every image before I add it to a page, after all nobody does. Let's leave that discussion open for a while. The thing is that not so many people are looking at the talk page to have their say about the image. I know wikipedia has a template for a section relevence that could be added to an article in order to direct people to a talk page. Do you know, if wikipedia has something like this for an image relevence? I also like to mention that somebody liked All sky Rays.jpg so much that he nominated it on fp.--Mbz1 14:50, 22 August 2007 (UTC)Mbz1

Mbz1, will you please stop putting that image at the top of the article? Whether or not it deserves inclusion, it certainly doesn't belong in the most prominent position when we have two Featured Pictures on offer. I've left it in the article for now pending further opinions as it isn't worth fighting over provided it's not at the head of the article, and as you mention, there are better ways to solve disputes. It's a real pity that that picture is so poor when viewed at full size, as it does look great in the thumbnail and it might have been a fantastic shot. But at full size the lack of focus, the colour and the clipping of highlights and shadows really let it down. I agree none of the templates you mention fit this scenario, but if you want to canvass further opinions, I reckon WP:RFC/STYLE would be the place to leave a link to this page. WP:3O is always a good place to get an independent view as well. Of course, I'm sure some of the veterans at Wikipedia_talk:Featured_picture_candidates would be happy to cast an experienced eye over the article for us and comment as to which pictures should be in and which shouldn't if we asked nicely. ~ VeledanT 22:38, 23 August 2007 (UTC)

            • You could remove this image and 2 of my other images from the article. I really care no more.--Mbz1 01:58, 24 August 2007 (UTC)Mbz1

I realize this is an old topic, but I stumbled across this finalist image from the 2008 photo competition: http://commons.wikimedia.org/wiki/File:Crepuscular_rays_in_ggp_2.jpg. Just curious if it should get included as well - I was a bit surprised to not see it here. Jeffhoy (talk) 16:27, 21 December 2012 (UTC)

Major clean up/Rearranged Article[edit]

I rearranged the article in a sequence of edits so now it better divided, similar things are arranged together and a lot easier to read. Added sections and toc to aid organization. It still needs a lot of inline references. Cleaned up the color explaination: although refraction does occur in the atmosphere chromatic aberration is not causing the colors ... Raleigh scattering (Tyndall effect) is. Kevin Purcell (talk) 18:48, 4 December 2008 (UTC)

Suggested image[edit]

Not that we needed more, but I just stumbled upon a great copyright free image that could be better than one of the existing ones: http://www.flickr.com/photos/library_of_congress/3548859587/ xlynx (talk) 13:10, 10 August 2011 (UTC)

File:Crepuscular rays at Sunset near Waterberg Plateau edit.jpg to appear as POTD[edit]

Hello! This is a note to let the editors of this article know that File:Crepuscular rays at Sunset near Waterberg Plateau edit.jpg will be appearing as picture of the day on April 8, 2013. You can view and edit the POTD blurb at Template:POTD/2013-04-08. If this article needs any attention or maintenance, it would be preferable if that could be done before its appearance on the Main Page. Thanks! — Crisco 1492 (talk) 23:41, 23 March 2013 (UTC)

Crepuscular rays
Crepuscular rays are rays of sunlight that appear to radiate from the location of the Sun. These rays, which generally appear around dawn and dusk, are columns of sunlit air separated by darker regions caused by obstructions.Photo: Alchemist-hp


Cleanup[edit]

"to converge at a point, the rays are in fact near-parallel shafts of sunlight, and their apparent convergence is a perspective effect"

Any lines that are near-parallel are not-parallel and thus do in fact converge at a point. Sunlight in particular is well known to converge at a point in the center of the solar system known as the sun.--76.121.41.214 (talk) 01:33, 4 December 2014 (UTC)