World Geographic Grid

Fig. 1-8: The world geographic grid consists of meridians of longitude and parallels of latitude. The prime meridian

( 0º) passes through Greenwich, England.

Typical Graph

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

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

Typical GraphEach point has

two values:The “X” value

that runs along the horizontal “X” axis

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

Y axis

X axis

Typical GraphX value is

always stated first

Followed by the Y value

The “origin” is the point where the 2 axes intersect with a value of (0,0)

(0,0)

(3,8)Y

X

(9,5)

Typical GraphA point can also

have negative (-) values

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

Negative 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

•Let the X axis be the Equator.•Let the Y axis be the

Prime Meridian that runs through Greenwich outside of London.•Lat/Long are the 2

grid points by which you can locate any point on earth.

Y

X

East West, North South on the Earth

Let each of the four quarters then be designated by North or South and East or West.

N

S

EW

East West, North South on the Earth

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

The 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

That means all 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

What would be the latitude and longitude directions in Australia?

Prime Meridian ?

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

What is Latitude?Latitude is the

distance from the equator along the Y axis.

All points along the equator have a value of 0 degrees latitude.

North pole = 90°NSouth pole = 90°SValues are

expressed in terms of degrees.

Y

X

90°S

90°N

What is Latitude?

Each degree of latitude is divided into 60 minutes.

Each minute is divided into 60 seconds.

Y

X

90°S

90°N

This is also true of longitude.

What is Latitude?

For Example:Latitude: 39°

4126' North. Longitude: 76° 4636' West...

This is close to where you live.

Y

X

90°S

90°N

What is Longitude?Longitude is the

distance from the prime meridian along the X axis.

All points along the prime meridian have avalue of 0 degrees longitude.

The earth is divided into two parts, orhemispheres, of east and west longitude.

Y

X

180°W 180°E

What is Longitude?

The earth is divided into 360 equal slices(meridians)

180 west and 180 east of the prime meridian

Y

X

180°W 180°E

What is Latitude?

Our latitude and longitude might be:

37°, 03’,13’’N

76°, 29’, 45’’W

Y

X

90°S

90°N

So Where is (0,0)?The origin

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

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

See If You Can Tell In Which Quarter These Lon/Lats Are Located

1. 41°N, 21°E2. 37°N, 76°W3. 72°S, 141°W4. 7°S, 23°W5. 15°N, 29°E6. 34°S, 151°E

A B

C D

1. B 2. A3. C4. C5. B6. D

World Time Zones

Fig. 1-9: The world’s 24 standard time zones each represent about 15° of longitude. They are often depicted using the Mercator projection.

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.

Map Scale: 1.The ratio of map distance to ground distance indicated on a map as a bar graph, representative fraction, and/or verbal statement2.Representation of a real-world phenomenon at a certain level of reduction or generalization

Expressions of Map Scale

Fig. A-1: Common expressions of map scale

Gradient of Map Scale

Fig. A-2: The scale gradient is frequently divided into three categories.

Large Scale maps depict a small area with great detail

•A large fraction (1:10,000) means a large scale, or smaller area

A small scale map depicts a large area with less detail

•A small fraction (1:1,000,000) means a small scale map showing a larger area

Scale DifferencesMaps of Washington State

Fig. 1-3: The effects of scale in maps of Washington State. (Scales from 1:10 million to 1:10,000)

Washington State (1:10 million scale)

Western Washington (1:1 million scale)

Seattle Region (1:100,000 scale)

Downtown Seattle, Washington (1:10,000 scale)

World Geographic Grid

Fig. 1-8: The world geographic grid consists of meridians of longitude and parallels of latitude. The prime meridian

( 0º) passes through Greenwich, England.