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Our
pojata : geographical data :
Google Earth is a
wonderful piece of software: not only that the aerial views of the
Earth surface are with a resolution of ten meters or better (some
highly populated areas with one meter resolution) but, as you
glide the pointer over the chart, the software displays longitude,
latitude and elevation at the pointer position. Longitudes and
latitudes are posted with a hundredths of a second precision,
elevations in one foot increments.
The longitude and
latitude precision seems unusually high; is it justified? The mean
Earth circumference is 40,007.86 km; it follows that the distance
on Earth surface corresponding to 0.01" amounts to
40,007,860/(360*60*60*100) = 0.3087 m. How nice: 1 ft = 0.3048 m,
i.e. longitudes and latitudes are given with the same precision as
elevations.
Nevertheless, it might
be a problem with the elevation numbers. Google Earth gives
for our pojata an elevation of 151 ft, which looks
reasonable. However, when pointer follows Grabov Rat sea water
front line, Google Earth gives elevations of 90 to 100 ft;
one has to point quite off-shore, probably around 50 meters, to
record elevation zero. The non-zero elevations at the shore can’t
be attributed to the tidal variations: Mediterranean Basin has no
tides of that magnitude. |
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