Location, Location, Location

 Two measurements define location on globe Measured in degrees from a starting point  Latitude Distance north or south of equator North also designated as positive  Longitude Distance east or west of a starting meridian Meridian: line running from pole to pole Prime meridian: through Greenwich, England Link

Starting point: Equator! Angular distance from equator measures latitude

Starting point: Prime meridian Angular distance east or west of prime meridian

 Globe is a model of Earth, showing locations of land and water  Great circle:  Map is a flat representation of part of Earth’s surface  Chart is a flat representation of ocean or air  Both maps and charts have distortion

 Projections are ways of transferring Earth structures/locations onto a flat map  Different projections are used for different purposes  Projections always create some sort of distortion

Medieval European T-O Map. In medieval Europe one of the most common forms of rendering the earth was the mappae mundi of which more than a thousand have survived. The T-O map is one kind of mappae mundi. The T-O image reproduced here comes from the encyclopedia of knowledge produced by Isidore, Bishop of Seville, in 630 A.D., and was printed in Augsburg in 1472.

The greatest "inventor" of sixteenth century Europe was map maker Gerhardus Mercator whose 1569 summary map, publicized by the learned Richard Hakluyt in his Principal Navigations, Voyages and Discoveries of the English Nation (London: 1589), liberated cartography from dependence on Ptolemy, and included a projection that allowed navigators to understand the coasts of the New World. These maps silently promoted a Eurocentric view that privileged the Western image. Generations of European and American students have been indoctrinated with the glories of nationalism and colonialism through this map.

 no matter how the earth is divided up, it can not be unrolled or unfolded to lie flat (undevelopable shape). P ROJECTIONS

(a) Azimuthal (gnomonic) (b) Cylindrical (c) Conic

Views of projected surfaces

Conical  Globe sits under a cone, touching along pre- selected line of latitude  Projection developed by cutting cone lengthwise and unrolling  Distortion greatest at latitudes distant from where cone ‘touches’ P ROJECTION C LASSIFICATION

Conical Polyconic Polyconic – envelopes globe with an infinite number of cones, each with its own standard parallel P ROJECTION C LASSIFICATION

Cylindrical  projected onto a cylinder which is also cut lengthwise and unrolled P ROJECTION C LASSIFICATION

Cylindrical Distortion  projection of the entire world, significant distortion occurs at the higher latitudes parallels become further apart and poles can not be seen P ROJECTION C LASSIFICATION

Cylindrical Distortion  sizes of Greenland vs. Africa Mercator Projection True size P ROJECTION C LASSIFICATION

Planar/Azimuthal  portion of earth’s surface is transformed from a perspective point to a flat surface P ROJECTION C LASSIFICATION

Mercator  cylindrical, conformal projection  angular relationships are preserved  parallels and meridians appear as straight lines  parallels are farther apart with increased distance from equator C OMMON P ROJECTIONS

Polar Stereographic  directions are true from center point  conformal projection: over a small area, angles in the map are the same as the corresponding angles on Earth's surface  meridians are straight and radiating; parallels are concentric circles  shows only one hemisphere C OMMON P ROJECTIONS

Robinson  developed to minimize appearance of angular and area distortion  distorts shape, area, scale and distance in an attempt to balance errors of projection properties C OMMON P ROJECTIONS

 size of an object on a map compared to the actual object on the ground  may not be the same in all directions from a point depending on projection used

S CALE T YPES Verbal scale  describes the scale in words i.e. “one centimeter represents one kilometer”  commonly found on popular atlases and maps

Visual scale (bar scale or graphic scale)  graphically illustrates relationship between map distance and ground distance. one end can be divided  most common  remains correct if reduced or enlarged S CALE T YPES

Visual scale (bar scale or graphic scale) S CALE T YPES

Representative Fraction (RF)  ratio (proportion) between map distance to earth distance i.e. 1:50,000  most versatile; not tied to any specific units S CALE T YPES

 large scale: show a small area with a large amount of detail.  small scale: show a large area with a small amount of detail  all relative L ARGE VS S MALL S CALE