Latitude and Longitude:

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Latitude and Longitude
Finding Locations on Planet Earth.
With thanks and credit to Step.com
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Typical Graph
This is an example of a typical graph. It is
made up of points that are connected by a line.
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Typical Graph
(4,7)
Y axis
Each point has two values
An X value that runs along the horizontal X
axis and.......
A Y value that runs along the vertical Y axis
Each point is expressed as an X value and a
Y value with the X value written first. For
example...
X axis
and...........
7,5)
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Typical Graph
Graphs may be divided into quadrants with the X
and Y values being either positive ()
or negative (-) depending on the quadrant in
which they are located.
Y
(-X,Y)
(X,Y)
X
Now lets apply the same principles to latitude
and longitude.
(X,-Y)
(-X,-Y)
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On the map horizontal lines are lines of latitude
and....
vertical lines are lines of longitude.
The X axis is the equator
and the Y axis which runs through Greenwich,
England is the Prime Meridian.
Equator
Prime Meridian
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Any location north of the equator is a NORTH
LATITUDE
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Any location south of the equator is a SOUTH
LATITUDE
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Any location west of the prime meridian is a WEST
LONGITUDE
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Any location east of the prime meridian is an
EAST LONGITUDE
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We can divide the Earth into quadrants NE where
all latitudes are NORTH and all longitudes are
EAST.
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We can divide the Earth into quadrants SE where
all latitudes are SOUTH and all longitudes are
EAST.
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We can divide the Earth into quadrants SW where
all latitudes are SOUTH and all longitudes are
WEST.
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We can divide the Earth into quadrants NW where
all latitudes are NORTH and all longitudes are
WEST.
Notice that EVERY point in the United States will
have a NORTH latitude and a WEST longitude since
we are in the NW quadrant.
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90N
What is latitude?
Latitude is the distance from the equator along
the Y axis.
It is expressed in degrees.
The north pole is 90 N
The south pole is 90 S
And remember that the equator is 0 latitude.
90S
0
What is the maximum possible latitude on Earth?
90 is maximum. You could be at 90N or 90S
but there is no greater latitude on Earth (or
anywhere else)
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What is longitude?
Longitude is the distance from the prime
meridian along the X axis.
Just like latitude, longitude is measured in
degrees.
The prime meridian is 0
And if you go half way around the world you
will reach the 180 longitude line.
0
180
180
Understand that there arent two 180 lines. On
this FLAT map it just looks that way. Its the
SAME line.
What is the maximum possible longitude on Earth?
180 is the maximum possible longitude on Earth.
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60N, 30W
75S, 75E
15S, 105W
Each box on this map is 15. With that in mind
how can we identify specific locations (red
dots)? Remember, write latitude first!
What are the coordinates of location......A
What are the coordinates of location......B
What are the coordinates of location......C
But what about location D ? Its in the middle of
a box. What do we do now?
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Lets use an example from the reference tables
(page 3). Look at Ithaca, NY.
43N
77W
76W
The latitude is more than 42N
but less than 43N
and the longitude is more than 76W
but less than 77W
Ithaca
42N
Each degree is about 111 kilometers so the
yellow-shaded box (1 x 1) in which Ithaca is
located covers over 12,000 square kilometers of
land. We need to be more precise. We can do that
by subdividing each degree into 60 smaller units
called minutes.
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If there are 60 minutes in each degree then
half a degree would be 30 minutes. Lets draw in
the 30 minute (30) line.
See these 2 marks?
They are half way (30) between 42N and
43N. Using a ruler, connect them.
The line you just drew is 4230N. Now lets look
at lines of longitude.
See these 2 marks?
They are half way (30) between 76W and 77W.
Using a ruler, connect them.
The line you just drew is 7630W.
Now lets see if we can locate Ithaca more
precisely.
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First comes latitude. Notice that Ithaca is just
south of the 4230N line. If its not quite 30
then lets call it 25. Ithaca is located
4225N.
Now well do longitude which, for Ithaca is easy
since its located right on the 7630W line.
Ithacas longitude is 7630W.
Now well put latitude and longitude together to
give a precise location Ithaca is 4225N ,
7630W.
Lets try another............................
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Lets find the location of Plattsburgh, NY to
the nearest minute.
First draw the 4430 line
Then, the 7330 line.
Now lets try to estimate the location.
Plattsburgh is more than 4430N but less than
45N. A good estimate would be 4440N.
Plattsburgh is more than 73W but less than
7330W. A good estimate would be 7325W
Putting the two together, Plattsburgh is about
4440N, 7325W.
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Here are some things to remember
gt Latitude is written first and must always
include N (north) or S (south) of the equator.
gt Longitude is written next and must always
include E (east) or W (west) of the prime
meridian.
gt All latitudes in New York State are N (north),
and all NYS longitudes are W (west).
gt Each degree of latitude or longitude can be
divided into 60 minutes.
gt A minute, as used here, is a unit of distance
on the earths surface. It is not a unit of
time.
gt The map on page 3 of your reference tables is
small and it is impossible to be absolutely
precise. Your best estimate should be to the
nearest 5 or 10 minutes. In other words, an
estimate of 7325W is OK but 7328W is
trying to be more accurate than is reasonably
possible with this map.
gt As with anything else you learn you will get
better with practice.........
SO PRACTICE, PRACTICE, PRACTICE!