Unnderstanding Longitude & Latitude

A Typical Graph

hThis is an example of a typical graph we are all familiar with.

hThe graph is made up of different “points” with lines that connect the points.

A Typical Graph

hEach point has two values indicating place:

hThe “X” value that runs along the horizontal “X” axis

hThe “Y” value that runs along the vertical “Y” axis

Y axis

X axis

A Typical Graph

hX value is always stated first, followed by the Y value

hThe “origin” is the point where the two axes intersect with a value of (0,0)

(0,0)

(3,8)Y

X

(9,5)

Typical Graph

hA point can also have a negative (-) value

hNegative X values are to the left of the origin (0,0)

hNegative Y values are below the origin

X

Y

(-X,+Y)

(+X,-Y)

(+X,+Y)

(-X,-Y)

(0,0)

East West, North South on the Earth

•The X axis is the equator.

hThe Y axis is the prime meridian that runs through Greenwich, England.

hLat/Long are the two grid points by which one can locate any point on Earth.

Y

X

East West, North South on the Earth

hLet each of the four quarters (quadrants) then be designated by North or South and East or West.

N

S

EW

East West, North South on the Earth

hThe N tells us we’re north of the equator. The S tells us we’re south of the equator.

hThe E tells us that we’re east of the prime meridian. The W tells us that we’re west of the prime meridian.

(N, W) (N, E)

(S, W) (S, E)

East West, North South on the Earth

hAll points in North America will have a North latitude and a West longitude because it is North of the equator and West of the prime meridian.

(N, W)

Prime Meridian

East West, North South on the Earth

hWhat would be the latitude and longitude directions in Australia?

Prime Meridian ?

If you said South and East , you’re right!

What is Latitude?hLatitude is the

distance from the equator along the Y axis.

hAll points along the equator have a value of 0 degrees.

hNorth pole = 90°N

hSouth pole = 90°S

hAll values are in stated in degrees.

Y

X

90°S

90°N

What is Latitude?

hEach degree of latitude is divided into 60 minutes.

hEach minute is divided into 60 seconds.

Y

X

90°S

90°N

This is also true of longitude.

What is Latitude?

hFor example,

h40° 02’ 51’’N

hThis is close to the latitude where you live.

Y

X

90°S

90°N

And Longitude? hLongitude is the distance from the prime meridian along the X axis.

hAll points along the prime meridian have a value of 0 degrees longitude.

hEarth is divided into two parts, or hemi-spheres, of east and west longitude.

Y

X

180°W 180°E

Meridians and Parallels?

hEarth is divided into 360 equal N-S slices (meridians)

-180 west and 180 east of the prime meridian

hEarth is divided into 180 equal E-W slices (parallels)

-90 north and 90 south of the equator

Y

X

180°W 180°E

Meridians and Parallels?

hMeridians of longitude run N and S, but are used to measure E and W.

hParallels of latitude run E and W, but are used to measure N and S

What is our location?

hCentral Peoria’s latitude and longitude are approximately:

h40°, 44’, 24’’N

h89°, 36’, 36’’W

Y

X

90°S

90°N

So Where is (0,0)?

hThe origin point (0,0) is where the equator intersects the prime meridian.

hPoint (0,0) is off the western coast of Africa in the Atlantic Ocean.

In which quadrants are the following latitudes and longitudes?

h1. 41°N, 21°E

h2. 37°N, 76°W

h3. 72°S, 141°W

h4. 7°S, 23°W

h5. 15°N, 29°E

h6. 34°S, 151°E

A B

C D

Let’s see how well you did...

h1. B

h2. A

h3. C

h4. C

h5. B

h6. D

Equator Latitude 0o

Latitude: (90oN to 90oS)

Latitude 23½o NorthTropic of Cancer

Latitude 23½o SouthTropic of Capricorn

Longitude 30o East

Longitude 60o East

Longitude 30o West

Longitude 60o West

Positioning on the Earth’s SurfaceEast is the direction of rotation of the Earth North Pole

South Pole

23½o 23½o

66½o 90o

900

21st June

22nd December

22nd Sept

20th March

30oE60oE90oE90oW30oW60oW

Longitude 90oEastLongitude 90o West

Prime Meridian

0o Longitude

Longitude: (180oE to 180oW)

Latitude and Longitude together enable the fixing of position on the Earth’s surface.

Now you are ready to find some locations on a map!