Latitude and Longitude is a system of geometrical
coordinates used in designating a precise location for all
points on the earth's surface. The latitude and longitude system
is based on angular distance measurement over a
curved surface of a sphere; the Earth. The latitude and
longitude system is one of many Geographic grids available to
use when referencing locations on Earth, such as working with
maps, globs and navigating.
Geographic Grids
A 'Geographic grid' is drawn on maps and
globes for the purpose of creating a unique position
identification system that can be used when referencing to any point on Earth.
Grid Lines
Two sets of grid lines encircle the globe:
parallel "lines of latitude" and "lines of longitude". The
parallel lines of latitude are horizontal, running from east to
west. The equator is the imaginary line from which latitude is
measured; it is equidistant from the poles, dividing the globe
into the northern and southern hemispheres. Latitude lines
become progressively shorter as they near the poles.
Longitudinal lines run from north to south, are
the same length and intersect at both poles.
The "prime meridian" is an arbitrarily selected
vertical longitude line from which all of the other longitude
lines are measured.
Angular Distance
Any location on the globe can be described in
terms of its angular distance from the reference points of the
equator (0° latitude) and the prime meridian (0° longitude).
Prime Meridian
In 1884 an official
international prime meridian was established in in London's
Greenwich Observatory, where a metallic marker was placed to
indicate its exact location.
Working
With Latitude & Longitude
Coordinates
Working with Latitude and
longitude is universal and a world stand. When working with
latitude and longitude information, a position's latitude is
given first followed by it's longitude. Latitude and longitude
are measurements over a curved surface of the Earth.
Latitude is the
measured position north or south of the equator, and is
expressed by angular measurements ranging from 0° at the equator
to 90° at the poles.
Longitude is the
measured position east or west of a the 'prime meridian', and is
measured in angles ranging from 0° at the prime meridian to 180°
at the International Date Line.
Length of a degree of
latitude change slightly as one measures from the equator to the
poles. This is due to the physical shape of earth, earth is
widest in the middle and narrows towards the poles. The
measurements vary from 110.57 km (68.70 mi) at the equator to
111.70 km (69.41 mi) at the poles. At the equator, meridians of
longitude 1 degree apart are separated by a distance of 111.32
km (69.17 mi). Meridian lines meet at the poles.
Each degree of latitude
and longitude is divided into 60 minutes, and each minute
divided into 60 seconds, thereby allowing the assignment of a
precise numerical location to any point on the surface of the
earth. Note, the smaller increments of the angle scale are
called minutes and seconds, but have no meanings or reference to
time.
The lack of common measuring devices like
rulers, odometers, etc. makes working with
latitude and longitude difficult and impractical for the average person, thereby
making this coordinate system useless and ignored.
The Modern Coordinate System
= UTM
Anyone that needs to measure outdoors, work
with maps, and use GPS will find working with
the more modern UTM flat grid coordinate system, that uses the
meter (the
international standard of measure) as the grid measure; a
much easier and faster way to measure, understand and
visualize.
The
UTM Coordinate System.
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Contributed By:
Gene Casanova, Certified
Equipment Specialists, International MASTER SCUBA Diver,
International Commercial Diver, Professional World Adventurer,
International Licensed Miner, Author, Webmaster, Mapping
Specialists
