OBJECTIVE TWW compare and contrast the components of various map projections in order to evaluate the optimal use of each projection for certain tasks

Map Projections Map projections  attempt to portray the surface of the earth or a portion of the earth on a flat surface Types of distortions: (1) conformality (2) distance (3) direction (4) scale (5) area

(1) Conformality When the scale of a map at any point on the map is the same in any direction, the projection is conformal. Meridians (lines of longitude) and parallels (lines of latitude) intersect at right angles. Shape is preserved locally on conformal maps

United States – 3 Ways

North America – 2 Ways

4 Categories of Map Projections (1) Cylindrical Projections (2) Conic Projections (3) Azimuthal Projections (4) Miscellaneous Projections

(1) Cylindrical Map Projections When the cylinder is tangent to the sphere contact is along a great circle (the circle formed on the surface of the Earth by a plane passing through the center of the Earth)

Other means of Cylindrical Projection

Cylindrical  (1) Cylindrical Equal Area straight meridians and parallels the meridians are equally spaced the parallels unequally spaced. Scale is true along the equator Scale is true along two lines equidistant from the equator Shape and scale distortions increase near points 90 degrees from the equator

Cylindrical  (1) Cylindrical Equal Area

Cylindrical  (2) Mercator Projection straight meridians and parallels that intersect at right angles. Scale is true at the equator or at two standard parallels equidistant from the equator often used for marine navigation because all straight lines on the map are lines of constant azimuth… constant direction

Cylindrical  (2) Mercator Projection

Cylindrical  (3) Mollweide Projection used for world maps The central meridian is straight. The 90th meridians are circular arcs. Parallels are straight, but unequally spaced. Scale is true only along the standard parallels of 40:44 N and 40:44 S

Cylindrical  (3) Mollweide Projection

Cylindrical  (4) Robinson Used by National Geographic based on tables of coordinates, not mathematical formulas distorts shape, area, scale, and distance in an attempt to balance the errors of projection properties Allows for slight distortion in all areas to not have extreme distortion in one.

Cylindrical  (4) Robinson

(2) Conic Projections projecting a spherical surface onto a cone. (a) tangent to the sphere contact is along a small circle (b) the cone touches the sphere along two lines, one a great circle, the other a small circle.

Conic Examples  Albers Equal Area distorts scale and distance except along standard parallels Areas are proportional and directions are true in limited areas. Used in the United States and other large countries with a larger east-west than north-south extent.

(3) Azimuthal (Planar) Projection result from projecting a spherical surface onto a plane. the plane is tangent to the sphere contact is at a single point on the surface of the Earth

Azimuthal  (1) Polar Projection Distances measured from the center are true. Distortion of other properties increases away from the center point.

Azimuthal  (2) Orthographic used for perspective views of hemispheres Area and shape are distorted. Distances are true along the equator and other parallel

(4) Miscellaneous Projections  Goode’s Projection Cut and paste … interrupts the oceans and Australia and New Zealand farther west than reality. Minimized distortion in shape of land masses

(4) Miscellaneous Projections  Dymaxion map depicts the earth's continents as "one island," or nearly contiguous land masses. The arrangement heavily interrupts the map in order to preserve shapes and sizes.

Matching Practice Activity to Best Choice of Projection ___ 1. Mollweide ___ 2. Robinson ___ 3. Dymaxion ___ 4. Albers Equal Area ___ 5. Mercator Anthropologist of equatorial countries Shipping captain visiting only the major ports of the world Editor of a geographic magazine Trip planner for a presidential candidate A scientist attempting to prove the idea of Pangaea

Matching  Activity to Best Choice of Projection __A 1. Mollweide __C 2. Robinson __E 3. Dymaxion __D 4. Albers Equal Area __B 5. Mercator Anthropologist of equatorial countries Shipping captain visiting only the major ports of the world Editor of a geographic magazine Trip planner for a presidential candidate A scientist attempting to prove the idea of Pangaea

IGNORE THE NEXT SLIDE!

Develop Your Own Situations Azimuthal/Polar Projection Goode’s Projection Orthographic Albers Equal Area