Re: [Paddlewise] Latitude distances

I posed the following "bonus" question:

> > As I noted above, the length of a
> > degree of latitude is "approximately" constant.  Why does it vary
> > ever-so-slightly (that part is easy) and at about what latitude does it
> > achieve maximum length?

Ted (fireball) and John Winters both provided correct answers.  John
wrote:

> According to the International Astronomical Union
> ellipsoid of 1964, the length of a degree of latitude is 68.708 statute mi
> at the equator and varies slightly north and south because of the oblate
> form of the globe; at the poles it is 69.403 statute mi.

Very good!  This works out to approximately 60.3 nautical miles at the
poles and 59.7 nautical miles at the equator.  (This also applies to the
WGS 84 ellipsoid.)

I have noticed that many of us who post to this list live somewhere in
the vicinty of 49 degrees North.  This far north, a degree of latitude
is approximately 60.1 nautical miles.  (At N45 degrees it is 60 nautical
miles.)

By the way, a "fun fact to know and tell" is that most Canadians live
south of the 49th parallel.  When I speak at Canadian conferences I like
to refer to the Canadians in the audience as my "neighbors to the
south".  Some of them get it, but most of them seem to assume that I am
just another geographically challenged American.

Dan Hagen
Bellingham, Washington
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