Finding your way in the world
Latitude lines are imaginary lines that run horizontally around the earth's
surface.
Think of latitude like the rungs of a ladder (ladder sounds a lot like
latitude). Latitude lines run horizontally and they tell how far up (north)
you can go or how far down (south) you can go.
Latitude lines run completely around the earth’s surface in
a horizontal direction. Latitude lines measure how far
NORTH or SOUTH a place is from the equator.
E Q U A T O R
The Equator ( 0° ) is located around the w i d e s t part of the earth.
Longitude lines are imaginary lines on the earth's surface that run from pole to
pole around the globe and tell you your distance east or west from the Prime
Meridian.
When you think of longitude, think of long, tall telephone poles (because
longitude lines run from pole to pole). Longitude lines run north and south, but
they tell how far east you can go or how far west you can go.
Why are latitude and longitude
measured in degrees?
In math, circles are measured in degrees. There are 360 degrees in a circle. Since
the earth is basically circular, it was decided to measure latitude and longitude in
degrees also.
The first latitude line was the Equator (equally distant between the north and
south poles). It is the largest of all latitude lines. All other latitude lines are
measured in degrees north or south of the Equator. There are a maximum of 90
degrees of latitude to the north or the south of the Equator.
The first longitude line was the Prime Meridian. Any meridian could have been
chosen as the Prime Meridian because they are all exactly the same.
There are a maximum of 180 degrees on longitude to the east or the west of the
Prime Meridian
For more accuracy in location, degrees can be divided into
smaller parts. One degree can be divided into 60 minutes (')
and one minute can be divided into 60 seconds ("). Seconds
can be divided into fractions of a second to get more
accurate.
Example: 29O 56’ 26.71’’ N
95O 43’ 6.89” W
This is the coordinates for the center of this classroom.
Most electronic GPS devices just use degrees and fractions
of minutes.
Example: The coordinates for this classroom:
29O 56’ 26.71’’ N
95O 43’ 6.89” W are shown as
29O 56.445’ N
95O 43.115’ W
Just divide the seconds by 60. 26.71/60=.445
6.89/60=.115
How do I use
latitude
and
longitude?
If someone asked you the location of the local town bank,
you may say "It is on the corner of Main and Third streets."
Latitude and longitude are like imaginary streets on the earth.
It is customary to give the latitude of a place first, and the
longitude second. For example, you would say "35 degrees
north, 77 degrees west". This eliminates the need to say the
words latitude and longitude.
Make sure that you give a direction with the number. If you
simply say "66 degrees latitude", there are two of them - one
in the north and one in the south.
To find a latitude line such as 60
degrees north latitude, you must do
three things:
1. Go to your starting line (the
Equator).
2. Determine which direction you
must go (north or south).
3. Determine the distance in degrees
you must go (60).
This will give the location of one of
your “streets”.
To find a longitude line such
as 40 degrees east longitude,
you must do three things:
1. Go to your starting line
(the Prime Meridian).
2. Determine which direction
you must go (east or west).
3. Determine the distance in
degrees you must go (40).
This will give the location of
one of your second street
If you find the intersection of these two imaginary streets,
you have found the exact (absolute) location of a particular
place on the earth's surface (shown by the red "X" on the
map found on the next slide.
Important: The Equator is neither North nor South of the
starting line, so it is simply 0º latitude (no direction needed).
The Prime Meridian would be 0º longitude (no direction
needed). Notice this on the two diagrams.