Talk:Latitude

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I think I know how to derive authalic latitude. Take the ellipsoid $E = (cosηcosλ,cosηsinλ, b sinη)$ and the sphere $S = (cosβcosλ,cosβsinλ,sinβ)$ . Note that $\partial E/\partial\eta\cdot\partial E/\partial\lambda=\partial S/\partial\beta\cdot\partial S/\partial\lambda=0$ so the areal elements are $|\partial E/\partial\eta||\partial E/\partial\lambda|$ and $|\partial S/\partial\beta||\partial S/\partial\lambda|$ so we equate those, throwing in an arbitrary constant factor and a correction factor for the different variables: $|\partial E/\partial\eta||\partial E/\partial\lambda| = A |\partial S/\partial\beta||\partial S/\partial\lambda|d\beta/d\eta$ . Expand to get $\sqrt{\sin^2\eta+b^2\cos^2\eta}\cos\eta\,d\eta=A\cos\beta \,d\beta$ , integrate (use $u = sinη$ ), adjust the arbitrary constants so $η = β = 0$ and $η = β = π / 2$ happen, and substitute $tanη = b tanφ$ and $b 2 + e 2 = 1$ . (I was all night getting the right pieces *shame*.) 142.177.169.65 15:41, 12 Aug 2004 (UTC)

The continents along the equator, Africa, South America, and Indonesia are the poorest

Is Indonesia a continent? Strange. --Nk 12:45, 5 Oct 2004 (UTC)

I think it's fair to state that Antarctica, with a GDP of approximately zero, is both a continent, and the poorest. But it ain't quite equatorial!--King Hildebrand 17:13, 8 February 2007 (UTC)

Another strange thing:

Each degree of latitude is further sub-divided into 60 "minutes". In modern navigation, part of a minute may be expressed as a decimal. A fully qualified latitude may be expressed thus; 13° 19.717′ N. Until the 1960s, parts of a minute were normally expressed in seconds; for instance 13° 19′ 42" N. There are 60 seconds in a minute.

This is outright wrong. Deg/min/sec is very common usage today, with fractional seconds for accuracy. The alternative is fractional degrees. Fractional minutes are in fact not so common. -- Egil 06:40, 12 Feb 2005 (UTC)

1 "angular measurement" ?
2 geodetic latitude is not referred to a plumb line
3 Distance between "Latitutdes
4 Latitude
5 Latitude and Wealth
6 Gravity
7 The Earth has no Latitude
8 Latitude - is it phi or lambda?
9 Astronomical latitude
10 This is a fringe theory
- 10.1 Evolutionary explanations

[edit] "angular measurement" ?

Article starts with:

Latitude is an angular measurement ranging from 0° at the Equator to 90° at the poles

is Latitude really an angular measurement? Since it's not really an angle but and evenly spaced distance apart? SimonLyall 13:59, 24 Mar 2005 (UTC)

Rectifying latitude is not geographic latitude.--Patrick 14:09, 24 Mar 2005 (UTC)

But is geographic latitude a "angular measurement" ? , sorry I'm not an expert but it just doesn't look right. SimonLyall 20:31, 24 Mar 2005 (UTC)

It is the angle between the equator plane and the line from the center of the Earth to the location.--Patrick 21:48, 24 Mar 2005 (UTC)

No, geocentric is the angle between the equator and a line from the center of the Earth. Geodetic and geographic are the same thing and are the angle between the equator and a normal to the reference spheroid. 2005 June 22, 13:44 EDT

[edit] geodetic latitude is not referred to a plumb line

This section is wrong: In common usage "latitude" refers to geodetic or geographic latitude φ and is the angle between a plumb line and the equatorial plane — because it originated as the angle between horizon and pole star. Because the Earth is slightly flattened by its rotation, cartographers refer to a variety of auxiliary latitudes to precisely adapt spherical projections according to their purpose.

Geodetic or geographic latitude is the angle between the equatorial plane and a line normal to a reference spheroid. Astronomical latitude is the angle between the equatorial plane and the normal to the local geopotential (ie a plumb line). These are not quite the same thing. I'll to figure out better wording to change this. 2005 June 22, 13:44 EDT

[edit] Distance between "Latitutdes

How does one calculate the distance (in meters) between two co-ordinates? I'm most intersted in finding out! --TheSimkin 16:44, July 20, 2005 (UTC)

I suggest a rewording of the sentence: "Reduced or parametric latitude β is the latitude of the same radius on the sphere with the same equator." to the following: "Reduced or parametric latitude β is the latitude of the same radius projected along the minor axis on the sphere with the same equator." Otherwise it could be confused with the Geocentric Latitude. Furthermore, I agree with EDT in referring the geodetical latitude to the (local) normal to the spheroid rather to the plumb line, but it seems to me that the math is congruent with the former, as geodetic and geocentric latitudes are in the correct relationship. [Netsaver]

[edit] Latitude

I can not calculate authalic latitude. Way over my head. Please avoid putting that in.

[edit] Latitude and Wealth

I think it is wrong to state that there is a distinct correlation. IMO there is a general correlation because there are many exceptions to the rule. In Africa the richest countries are South Africa and Nigeria, Nigeria is a clear exception. Also within richer countries (e.g. the UK), the North is poorer than the South. There are way too many factors to state categorically that the closer you are to the equator the poorer you will be. I think this section needs rewording to take this into account. --138.37.219.207 12:01, 10 April 2006 (UTC)

I agree. This discussion seems out of place in this venue. Perhaps this can be moved to its own category? S Schaffter 18:45, 26 July 2006 (UTC)

I agree that the 'correlation' (soundly debunked) should be moved to its own page, or possibly merged with http://en.wikipedia.org/wiki/Charles_de_Secondat%2C_Baron_de_Montesquieu, http://en.wikipedia.org/wiki/Eugenics, or http://en.wikipedia.org/wiki/Industrial_Revolution.

I'm not saying these are perfect places to put it, but they're markedly better than an article on navigation. Sorry, but I don't know how to use wikilinks -- FM.

I agree with moving these sections out. They are not central to the topic and they are fringe theories. —The preceding unsigned comment was added by Futurebird (talk • contribs) 02:26, 13 March 2007 (UTC).

[edit] Gravity

I've heard that gravity changes depending on your latitude, at 45.5° (and sea level) acceleration due to gravity is 9.80665m/s². How much does that change as you go north or south?

Gravity is the attraction between two masses so gravitational force is independent of location on earth (grossly made assumptions about altitude, land vs. water, spherical planet, yada, yada). On the equator the angular velocity is much higher than if you travel away from the equator; since the rotation is wanting to throw you off the planet (think being at the edge of a merry-go-round vs. in the center) then your weight will be less on the equator. Cburnett 05:31, 25 August 2006 (UTC)

The Earth to a first approximation is a sphere, and Cburnett's comments apply. A second approximation notes the flattening of the poles by about 40 km relative to the equator (can't remember offhand whether this figure applies to radius or diameter). Therefore you're closer to the centre of the Earth at the poles, and hence gravity is greater. Then throw in mountains and depressions, each varying your distance from the centre - the lower you go, the greater the acceleration due to gravity becomes. Finally recognise local density variations in the rocks making up the Earth's surface (deeper ones have little effect). If you're standing above a copper mine, you will experience greater gravity than if you're on sedimentary rock or ocean. --King Hildebrand 17:24, 8 February 2007 (UTC)

[edit] The Earth has no Latitude

The Earth has no Latitude because it is flat. Latitudes are curved but they can't be present b/c our planet is flat. It absolutely is. Because it isn't... think of a ball... ur on a ship and u go over the curved part and you'll be upside down. so that doesnt happen so earth is flat and so earth has no latitude.

I agree I think there is a POV problem with this article. I would like to see some proof that the world is round.

I'm going to commit suicide because of the mental retardation of whoever wrote those. Gravity keeps stuff from "falling down" if its upside down. But wouldn't (if your on the bottom of the round earth) up be the down of the top of the earth? If that doesnt make any sense jsut forget about it and keep thinking the earth is flat.

[edit] Latitude - is it phi or lambda?

I'm studying for a college exam and came across two different opinions....Wikipedia's and Nasa's. If you go to http://www-istp.gsfc.nasa.gov/stargaze/Slatlong.htm they state that latitude is lambda and longitude is phi. Your articles are just the opposite. Thought you might want to verify this and ensure your website is correct.

It depends on what source you use! P=/

In all of the (particularly geodetic) articles and formularies I've seen, latitude = phi and longitude = lambda (though, in a lot of ellipsoidal formularies, lambda is used as the ellipsoidal/auxiliary longitude and either "L" or something else is used for the geodetic/geographic longitude): See Vincenty (PDF) and Borre (also PDF). A basic explanation about these types of discrepancies can be found here (further confusing things!!! P=) ~Kaimbridge~15:49, 4 November 2006 (UTC)

[edit] Astronomical latitude

Why do you call it "obscure"? To me it seems to be the most natural notion of latitude, the one the most easily to measure.

To me, e.g., reduced, authalic and conformal latitude seem to be much more obscure. Do they have any application or are they just mathematically interesting? --84.159.207.253 12:21, 2 December 2006 (UTC)

[edit] This is a fringe theory

I don't think it makes sense to put it here. It could go in the article on J. Philippe Rushton. futurebird 02:25, 13 March 2007 (UTC)

[edit] Evolutionary explanations

The neutrality of this section is disputed.
Please see the discussion on the talk page.

One controversial explanation currently being advocated by certain evolutionary psychologists, is claimed to be grounded in evolutionary theory. Some have argued that as humans migrated into higher latitudes and encountered colder weather there, the cold weather forced the evolution of higher group intelligence by forcing inhabitants to perform more intellectually demanding tasks, such as building shelter, fires, and clothing, in order to survive (Lynn, 1991).

One study that supports this notion was performed by Beals et al. (1984, p. 309), who found a correlation of 0.62 (p=0.00001) between latitude and cranial capacity in samples worldwide and reported that each degree of latitude was associated with an increase of 2.5 cm³ in cranial volume.

Researchers such as psychologist J. Philippe Rushton have argued that the association of greater brain size with greater latitude is due to the fact that cold weather imposes on its inhabitants more cognitively demanding tasks such as the need to construct shelter, make clothing, and store food.

Nevertheless, these explanations seem to be contradicted by the fact that it was in Africa, at near equatorial latitude, that harsh conditions such as extreme drought have brought our species, homo sapiens, to existence. Another contradicting observation is the high number of advanced civilizations that flourished near the equator -- such as Sumerian, Egyptian, Hindu among many others. The demanding tasks of shelter construction, cloth making and food storing, seem to be less likely to have constrained man's evolution since the invention of agriculture and writing.

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