Talk:Circle of latitude

"Cahne" of 1 grade

Considering the earth as a sphere, a cahne of 1 grade moves over the surface about 110 km, as far as I can remember... maybe somebody have better data for this????

What is a "cahne of 1 grade" ? For that matter, WTF is a "cahne" ? StuRat 04:11, 21 November 2005 (UTC)

I'm thinking that this should be a "change of 1 degree", since that makes the numbers work out. Izzycat 00:24, 10 January 2006 (UTC)

That diagram is neat, but inaccurate. The Tropic of Cancer most certainly does not pass through Spain. Nelnadon 02:58, 18 December 2005 (UTC)

You're exactly right. That's plate-carré projection, which means it doesn't line up with the circle at all. Ojw 11:58, 18 December 2005 (UTC)

Shouldn't the arctic circle be said to enclose the *southernmost* point in the northern hemisphere (and vice versa for the antarctic circle)?72.253.5.120 07:41, 2 February 2007 (UTC)

• Kind of, although saying it "encloses" such a point doesn't actually define it at all. Any circle of latitude south of the Artic Circle also "encloses" that same point (depending on your understanding of what "encloses" means on a sphere, I guess). That section was all pretty muddled IMO, and I have attempted to make it clearer.

45S

Is this **really** notable? --Belg4mit 14:11, 23 April 2007 (UTC) ...

No. Furthermore, it's wrong because meridians aren't circles but ellipses. --84.151.27.83 (talk) 14:40, 17 December 2010 (UTC)

Error

"Circles of latitude are often called parallels because they are a fixed distance apart..." No, they are not a fixed distance apart. They aren't even separated by a fixed angle, as the shape of the Earth is a spheroid, not a sphere. SharkD (talk) 08:36, 17 February 2008 (UTC)

Fixed. Bazonka (talk) 17:10, 11 October 2008 (UTC)

Mercator projection equidistant intervals?

"On some map projections, including the Mercator projection, they are drawn at equidistant intervals."

The lines of latitude are closer together nearer the equator on the Mercator projection.

Mms7 (talk) 03:57, 22 March 2009 (UTC)

 Fixed   Set Sail For The Seven Seas  276° 45' 00" NET   09:38, 25 July 2009 (UTC)

Parallels as borders

Someone objects to this rewrite:

"==Other notable parallels== A number of sub-national and international borders were intended to be defined by parallels.(Usually the line that was marked off on the ground to define the actual border didn't quite match the intended parallel.)"

The rewrite is correct, of course; we probably all agree about the intention, and anyone who looks at a few maps can see the actual borders rarely follow the intended parallel. (Probably never, on land.) The surveyors did their best, but they couldn't be expected to get it exactly right. They placed their markers, and the line they marked became the border.

Can anyone find a boundary on land that is actually "defined" by a parallel, rather than by the line that was surveyed and marked to (unsuccessfully) try to follow the parallel?

(If it's a state line in the US, we have the additional problem that the NAD83 parallel may be a few meters away from the NAD27 parallel. But when the border was surveyed neither NAD27 nor NAD83 existed-- it's a coincidence that the surveyors got as close as they did.) Tim Zukas (talk) 22:05, 17 October 2011 (UTC)

The problem with your edit is that it is written as though it applies in all cases. It clearly does not, as you yourself have implied above in your comment where you specify that it applies to land borders. However, your edit did not make a distinction between land and water borders. Also, some borders are defined by statute or treaty to be on a particular parallel. Marker posts may have been imprecisely placed, but it is the document or agreement that legally defines the border, not the markers. In other cases (particularly for sub-national borders), no markers at all will have been used. The previous edit ("A number of sub-national and international borders are defined by, or are approximated by, parallels") is accurate, succinct and correct, and I see no need to change it. Bazonka (talk) 07:29, 18 October 2011 (UTC)

"some borders are defined by statute or treaty to be on a particular parallel. Marker posts may have been imprecisely placed, but it is the document or agreement that legally defines the border, not the markers."

That's where you're wrong, of course. You think when the map shows the CA-OR state line to be maybe 500 meters south of latitude 42, the border as shown on the map isn't the "legal" border. Any theories about why they put that line on the map?

Most state boundaries in the US that were intended to follow parallels are off by 100 meters or more, according to the topo maps. Why do you think the mapmakers drew the alleged border where they did?

What would be the point of surveying and marking the boundary, if the markers were not intended to define the border? Why spend the money on the survey?

It seems the Adams-Onis Treaty of 1819 set the north boundary of Spanish/Mexican territory at latitude 42 degrees. Probably the treaty didn't say anything about how that was to be determined; probably it didn't say whether it was to be astronomic latitude, and it certainly didn't say it was to be NAD27 or NAD83 latitude. Maybe they didn't mention surveying and marking the boundary, and you figure if they didn't then markers can't be the legal boundary. Lotsa luck finding anyone to agree with that. Tim Zukas (talk) 23:50, 18 October 2011 (UTC)

You should not assume that what happens in the US is also what happens elsewhere - your proposed wording seems to make this assumption. To be honest, I'm not absolutely sure how (or if) all circle-of-latitude borders are marked or enforced around the world (and I doubt that you're sure either), but certainly it is correct to say that they are approximated by the parallels. And your points about the different latitude definitions are an irrelevance, the borders are still defined by a version of the latitude. I still fail to see anything wrong with the current wording. Bazonka (talk) 07:09, 19 October 2011 (UTC)

"the borders are still defined by a version of the latitude."

You seem to imagine that the border shown on the map is not the border. Why?

You seem to imagine the border isn't marked by the markers placed to mark the border. Why? What are the markers for? Tim Zukas (talk) 20:53, 19 October 2011 (UTC)

No, that's not what I think at all. Whilst the California/Oregon border might be legally defined by marker posts (which are not on the parallel due to imperfect surveying), it still approximates the parallel. And not all borders are marked by posts. Certainly the marine ones aren't, and quite possibly many others - I don't know this for certain but I'm fairly confident that the 42nd and 46th parallels south, which define borders of Argentinian provinces wouldn't be demarked, at least not along their entire length across the Patagonian pampas.

The current wording ("A number of sub-national and international borders are defined by, or are approximated by, parallels") applies in both cases - where the border is defined by imprecisely placed marker posts ("approximated by") or where the actual parallel is the border. Your wording does not apply in all cases. Bazonka (talk) 16:56, 20 October 2011 (UTC)

Good-- maybe we're getting somewhere. You've abandoned the notion that "it is the document or agreement that legally defines the border, not the markers"? You agree if there are markers, they mark the legal border? So how about maps? Are you willing to accept that the border shown on the map is the border, whether it's on the parallel or not? Tim Zukas (talk) 19:55, 20 October 2011 (UTC)

No, I have not abandoned the notion that "it is the document or agreement that legally defines the border, not the markers". Where there are markers, they (usually) define the border's location. But there aren't always markers!!! That's my point.

Is the border shown on the map the border? Perhaps, perhaps not. Depends on the situation on the ground, and the accuracy of the cartography. Bazonka (talk) 20:29, 20 October 2011 (UTC)

"Where there are markers, they (usually) define the border's location."

Got an example where there are markers and the border is elsewhere?

"But there aren't always markers!!! That's my point."

Everyone's agreed there aren't always markers. Everyone's agreed the markers don't mark the border if there are no markers.

"Is the border shown on the map the border? Perhaps, perhaps not."

Got an example where it isn't? Tim Zukas (talk) 16:16, 21 October 2011 (UTC)

Let's get to the point: exactly what is wrong with this sentence "A number of sub-national and international borders are defined by, or are approximated by, parallels"? Bazonka (talk) 16:31, 21 October 2011 (UTC)

If by "wrong" you mean "incorrect", then nothing whatever is wrong with it. You could delete the whole sentence-- the whole section-- the whole article-- and what remained would be correct. But when you say "what is wrong with this sentence" you actually mean "this sentence seems unimprovable". It's easy to improve, and amplification will help anyone who wants to learn about borders that are/were intended to follow parallels. Tim Zukas (talk) 19:40, 21 October 2011 (UTC)

By all means make improvements, but please don't replace the sentence wholesale with something that only applies in some situations. Note that I already improved the sentence since you first tried to change it by adding "or approximated by". Bazonka (talk) 14:13, 22 October 2011 (UTC)

Late to the show, but ... don't most boundary laws or treaties provide for a boundary commission and survey? And then, once the government(s) formally accepts the final report of the survey, it's that survey that defines the boundary. Moreover, the markers that the surveyors put down are connected by straight lines (usually rhumb lines, unless the surveyors get fancy and say otherwise). Nevertheless, it's the accepted *report* that defines the boundary, not the physical markers. Otherwise someone (or Mother Nature) could change the boundary just by moving the markers in the dead of night.

For an example, see United States and Mexican Boundary Survey ExtonGuy (talk) 20:18, 11 March 2013 (UTC)

Don't see any example there.

The report defines the boundary, unless it doesn't. Do you think this US-Canada border marker defines the border?

http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=TM1015

It's not latitude 49 degrees in either datum, or astronomically either. Think the border is somewhere else? If so, what tells us where it is?

"the markers that the surveyors put down are connected by straight lines (usually rhumb lines)..."

Just to clarify: rhumb lines usually aren't "straight". Hard to see why anyone would want to bother with rhumb lines when marking a border. Tim Zukas (talk) 17:27, 12 March 2013 (UTC)

Other notable parallels

It should be added: 28ºS In Argentina, part of the border between Chaco Province and Santa Fé Province. — Preceding unsigned comment added by 190.183.86.125 (talk) 17:46, 21 November 2011 (UTC)

Added. Bazonka (talk) 19:38, 21 November 2011 (UTC)