Talk:Latitude

message: Currently, the article uses  for the geocentric
latitude.  This is, I beliveve, a non-standard usage and it conflicts
with the use of  for isometric latitude.  I propose to
use  instead.  There is now a conflict with the use of
 as the colatitude for spherical coordinates; so I
further propose using  for that quantity (with the
prime used to connote the co-quantity).  Comments?
By the way, I've updated the section on numerical comparisons to use
the parameters for the WGS84 ellipsoid and to plot the signed
difference.  It seems that my change to the figure will take a while
to percolate through to the article page.  (It was too easy for people
to look at the old figure and assume that the auxiliary latitude were
bigger can the geodetic latitude -- although the text did try to address
this issue.)
cffk (talk) 13:25, 29 August 2018 (UTC)
replies: text: Yes, please. Strebe (talk) 14:33, 29 August 2018 (UTC)
replies: text: Done.   your figures needs updating; perhaps you can take care of this?  Let me know if there are any issues. cffk (talk) 18:01, 30 August 2018 (UTC)
thread_title:  Nomenclature for geocentric latitude 

message: The section "Geodetic and geocentric latitudes" says:
Geographic latitude must be used with care. Some authors use it as a synonym for geodetic latitude whilst others use it as an alternative to the astronomical latitude.
The geodetic latitude is defined with respect to the ellipsoid surface normal. The astronomical latitude is said to be defined with respect to a plumb line. However, on an ellipsoid in gravitational-rotational equilibrium the surface normal and the plumb line should be the same, shouldn't they? I assume that corrections for atmospheric correction, height of observer etc need to be made for precision measurements and thus should not affect the relation between the two latitude types. 150.227.15.253 (talk) 21:29, 26 January 2021 (UTC)
replies: text: See the section “Astronomical latitude”. Strebe (talk) 03:59, 27 January 2021 (UTC)

text: The plumb line may also be affected by the thickness of the Earth's crust at a particular point. Mountains versus oceans for instance. The difference may be inconsequential however. ➧datumizer  ☎  05:07, 5 February 2021 (UTC)
thread_title:  Geodetic and astronomic latitude 

message: The article currently states: "[Geodetic latitude] is the definition assumed when the word latitude is used without qualification." This statement is repeated (nearly verbatim) elsewhere across related Wikipedia articles. I believe it could use some clarification and possibly sourcing.
My guess is that most (lay) people, if asked to try to define latitude themselves, would come up with the geocentric latitude, or at least I know I would have before I learned that there are (at least) two definitions in use. When we use the passive voice here—"is assumed," "is used"—it begs the question, by whom?
So two thoughts:
Can we specify some examples of specific contexts in which each one is most commonly used? When is geocentric latitude used? E.g. Google Maps uses geodetic latitude.
Can we source this statement of geodetic as the norm, and/or these specific contexts in which it is or is not the norm? E.g. Google Maps documentation or the World Geodetic System article and the section on WGS84. RileyJohnGibbs (talk) 19:57, 1 August 2023 (UTC)
replies: text: It’s all about the official locations of things. Surveying measures geodetic latitudes; traditional techniques have no way of measuring geocentric latitude. Every national system of mapping uses geodetic latitudes for that reason. Hence all official documentation, worldwide, is in geodetic coordinates, which means the latitude is geodetic. However, the datum varies from locale to locale, which means that two different surveys do not assign the same geodetic latitude to the same point. Nevertheless, each would be a geodetic latitude. My library in storage for awhile, so I can’t just pull up the usual texts. Poking around online should confirm what I’m saying here, though. Strebe (talk) 21:23, 1 August 2023 (UTC)

text: Here's an explanation, although it's not one we can cite. Everyone just seems to take geodetic latitude for granted, but it's hard to find a reference that says that. Apocheir (talk) 02:21, 2 August 2023 (UTC)
thread_title:  Usage of geodetic vs geocentric