Talk:Sunbeam

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'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)[reply]

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)[reply]

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)[reply]

I think the citation already in the article (Les Cowley's site) implies that crepuscular rays are usually called that during twilight, and are called "sun rays" or "cloud shadows" during the daytime. — Preceding unsigned comment added by 208.46.80.226 (talk) 21:23, 12 August 2019 (UTC)[reply]

Here is another citation that tries to clarify this^[1] — Preceding unsigned comment added by 208.46.80.226 (talk) 21:32, 12 August 2019 (UTC)[reply]

Users 208.46.80.226 and 85.210.55.88 are both correct --- Crepuscular rays only refer to rays caused by the sun below the horizon. See ^[2] for another reliable source. This article needs to either be retitled or refactored. —hike395 (talk) 10:00, 13 August 2019 (UTC)[reply]

Later --- the definition of crepuscular ray from Mirriam Webster^[3] supports the fact that they are sunbeams that occur near twilight. I think that the article needs to move. I've rewritten the article to be about sunbeams, with crepuscular rays as a section.

"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)[reply]

I stumbled upon this today and I agree. There is no reliable source given for this sentence, either. So here's a late response: I'm removing the sentence, and it must not be added without a valid reference again. ~ ToBeFree (talk) 03:13, 7 May 2018 (UTC)[reply]

https://en.wikipedia.org/w/index.php?title=Crepuscular_rays&diff=840003408&oldid=839426172&diffmode=source ~ ToBeFree (talk) 03:16, 7 May 2018 (UTC)[reply]

Sentence said "near-parallel". Restored sentence with reference to instructional notes from UIUC. —hike395 (talk) 08:34, 7 May 2018 (UTC)[reply]

Wow, thanks! I checked the sources referenced in the lead section, but could not really be convinced until I saw the NASA photo below. I would have added it now, if you hadn't already added it too. That's a really amazing one! So yes, these rays are both "not really exactly parallel" and at the same time "by far not as converging as they look like". They do converge towards the sun, but the sun is so far away that the optical illusion of "convergence" in the pictures is really something different than the actual physical convergence of these sunrays. ~ ToBeFree (talk) 18:10, 7 May 2018 (UTC)[reply]

The diameter of the sun is much larger than the distance between the rays, or width of the individual ray. Therefore you cannot treat the sun as a point-like source and the rays as one-dimensional lines. In fact the extrapolated rays would be growing in diameter as you get closer to the sun. Sentence that they converge toward the sun doesn't make much sense, or at best is extremely confusing. Out of three references given, the two accessible online don't claim the rays converge towards the sun. 2A01:CB15:86:DB00:A8D8:D3AB:A38A:8AC2 (talk) 09:09, 6 October 2018 (UTC)[reply]

I added this term ("splintered light"), which I've known since childhood (and apparently Tolkien used) and cited a Google Book search for the 18th and 19th centuries. Is this ok form?Mrzold (talk) 10:52, 15 August 2018 (UTC)[reply]

The cover of Splintered Light indeed has a picture of crepuscular rays, so it would appear that Tolkien did use the term to refer to them (although we'd have to have access to the entire book to be sure), but do any of the other hits in your Google Books search specifically do so? Going by the cited passages, I get the impression that they use the term as a metaphor for all sorts of phenomena, not just crepuscular rays. If this is true, perhaps it is better to limit the reference to the Tolkien book only. Drabkikker (talk) 11:44, 11 August 2018 (UTC)[reply]

My impression is that this article covers both a technical definition of a phenomenon and the terms of art associated with it. Mrzold (talk) 10:51, 15 August 2018 (UTC) I think this is a poor citation. I'm removing it. I'll try to find a better one.Mrzold (talk) 20:29, 16 August 2018 (UTC)[reply]

"Light shaft" redirects here. However this academic paper uses that phrase for (one of the meanings of) Portuguese "saguão", a usually small unroofed “gap” inside a building (or between two contiguous, tangent buildings), often with only windows opening to it, meant for ventillation and sunlightning. Assuming this translation is correct, maybe this completely different meaning should warrent disambiguation, at least? Furthermore, a Commons category is needed for this notion, and this redirect in a sister project might conflict with it. Tuvalkin (talk) 15:02, 18 February 2019 (UTC)[reply]