elevation vs. altitude

[Adolf Ceska]

> I am curious about the reason "elevation" is used for "altitude".  The
> use of elevation is well entrenched in the US, but the rest of the world
> uses altitude.  Elevation is the difference in height between two
> locations: e.g., Calgary is at 1080 m altitude, and Edmonton is at 670 m
> altitude; the difference in elevation is 410 m.  Altitude is the height
> above MSL (mean sea level) of a given location.

Webster' New Dictionary of Synonyms:

"While ALTITUDE and ELEVATION are often interchangeable, Altitude may be
preferred in referring to vertical distance ABOVE the surface of the earth
... *** <an airplane flying at an altitude of 12,000 feet><the altitude of
a cloud> Elevation is used especially in reference to vertical height
above sea level ON the surface of the earth; thus one would speak of the
altitude of a balloon; a village situated at an elevation, preferable to
altitude, of 2000 feet ... "

Adolf Ceska
P.S. *** altitude also refers to "the vertical distance above the horizon
in angular measurement <the altitude of a star>" Webster ...