Talk:Latitude

I think I know how to derive authalic latitude. Take the ellipsoid $E=(\cos \eta \cos \lambda ,\cos \eta \sin \lambda ,b\sin \eta )$ and the sphere $S=(\cos \beta \cos \lambda ,\cos \beta \sin \lambda ,\sin \beta )$. 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 $u=\sin \eta$), adjust the arbitrary constants so $\eta =\beta =0$ and $\eta =\beta =\pi /2$ happen, and substitute $\tan \eta =b\tan \phi$ 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)

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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)

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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)

"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

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

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]

Latitude

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

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)

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?