Map Projections

A map projection makes a huge difference in the way a country appears.

Types of map projections I. Cylindrical projections result from projecting a spherical surface onto a cylinder.

A. Characteristics of Cylindrical Projections 1. Straight meridians & parallels 2. Meridians are equally spaced; parallels are unequally spaced. 3. Scale is true along the center line; it distorts near the poles. The Peters Projection minimizes distortion in the higher latitudes.

B. Kinds of Cylindrical Projections Gerardus Mercator

1. Mercator Projection a. Straight meridians and parallels. b. Scale is true at the equator. c. Often used for marine navigation d. Distorts areas near the poles

2. Robinson Projection a. Distorts shape, area, scale, and distance. b. Attempts to balance the errors in projection

3. Sinusoidal Equal Area a. Straight parallels at right angles to a central meridian b. Scale is true only on the central meridian and the parallels c. Often used in countries that are larger north to south than they are east to west

II. Conic projections A. Result from projecting a spherical shape onto a cone

B. Characteristics of Conic Projections 1. Usually distorts scale and distance 2. Areas are proportional 3. Directions are true on a limited basis 4. Used in countries like the United States which are larger east-west than they are north-south

III. Azimuthal Projections A. result from projecting a spherical surface onto a plane

B. Uses of an Azimuthal Projection 1. To show air-route distances 2. To map large ocean areas 3. For perspective views of hemispheres 4. For navigation in polar regions

IV. Interrupted Goode Homolosine Projection A. Accurate shapes and areas B. Difficult to show distances across the ocean C. Looks like a globe that was cut and flattened

The more of what is being measured, the larger the area. Cartograms The more of what is being measured, the larger the area.

Choropleth maps Show how much of what is being measure d there is; the darker the color, the more there is.

Scale Scale is the relationship between distance on the map and distance on the ground. A map scale is usually given as a fraction or a ratio.

Which Map? Maps are valuable tools. Different types of maps are suited to different types of jobs You need to tell me what type of map would be used for the following projects: 17

___ 3. A study comparing population densities in different states ___ 1. A study mapping watersheds in a region, used to determine risk of flooding. ___ 2. An article describing the countries in the area that was once Yugoslavia ___ 3. A study comparing population densities in different states ___ 4. A report about the different kinds of economic activity in a region ___ 5. An itinerary for a traveler who plans to visit several different countries ___ 6. A route plan for a hiker in the White Mountains of New Hampshire ___ 7. A government study of natural resources 18

List of maps to chose from: political map physical map thematic map 19