1. Map Projections

9. Tools of Geography
The most useful tool for looking at where things are in the WORLD is a globe
It is an accurate, miniature of the actual earth
It shows correct distance, size (area), shape, and direction

10. From Globe to Map
Every flat map misrepresents the globe in one way or another—NO EXCEPTIONS!
This is because the globe is a three dimensional object and maps are two dimensional
EVERY MAP IS DISTORTED!!!
Imagine peeling off an orange peel in once big piece. When you put it back together without the orange inside, it still forms a sphere. If you try to make it into a flat surface, the pieces tear apart.

12. Global Gores
One way to try to overcome the problem of turning a globe into a flat map is global gores
The globe is cut into sections to make the map
However, the sections are still somewhat distorted
Also, it is not very useful to read a map with gaps in the middle of places

13. So, how do they make maps? Through projections!!!
Instead of “cutting up the globe,” they “project” it onto paper.
Imagine a light bulb inside of the globe that casts shadows of land formations onto a piece of paper.
If we trace the shadows, we have a map

14. Why are there different map projections?
Depending on WHERE and HOW they hold the paper, we get different types of maps.
Most common are cylindrical, conical, and azimuthal (planar) projections

15. Cylindrical Projections

16. Conic Projections

17. Planar (Azimuthal) Projection

18. Map Distortions Unfortunately, all maps are DISTORTED
All maps have at least one distortion
Four things get distorted on maps
Some maps will distort some things and not others
DISTANCE: How far apart things are
SIZE (AREA): How big a place is
SHAPE: What the form of a place looks like
DIRECTION: Where places are in relation to each other; In other words, which direction should you REALLY go if you want to get somewhere?

19. Distance Distortion
Unequal
Equal
Mercator

20. Size (Area) Distortion
Miller Cylindrical

21. Shape Distortion
Gall Peters

22. Direction Distortion
Inaccurate
Accurate

23. Three Categories of Maps
Conformal: Show true SHAPES but distorted SIZES
Equal-Area: Show true SIZE but distorted SHAPES
Compromise: Show some SIZE distortion in order to portray shapes more accurately

24. Mercator Projection Conformal Map Used for navigation of ships
Good: True direction shown at any two points on a straight line
Bad: Size distortion at higher
latitudes

25. Robinson Projection Compromise Map Uses: Educational materials
Good: Reasonable overall picture of the world
Bad: Distortion in polar areas

26. Azimuthal Projection Compromise
Uses: Pilots use it to find the Great Circle Route (see next slide)
Good: Shows accurate direction
Bad: Distance and size distorted

27. Great Circle Route
A great circle path is the shortest path on the surface of a sphere between two points on that sphere
It is shorter to take a circle route and fly with the curve of the earth, than to take a straight line
The great circle as plotted with 5° of longitude between the waypoints is 4627 M
The composite route as plotted with 3° of longitude between waypoints is 4669 M.
The rhumb line is 4843 M.