Latitude and Longitude Angular distance in ° between center of the earth and a point on the earth’s surface parallels Longitude Angular distance in ° east or west of a point on the Earth’s surface meridians

LAT AND LONG LATITUDE- MEASURES N AND S OF EQUATOR (0 TO 90°) BUT RUNS E AND W LONGITUDE MEASURES E AND W OF PRIME MERIDIAN (O TO 180°) BUT RUNS N AND S

LATITUDE AND LONGITUDE EQUATOR 0° NEW ORLEANS 30°N 90°W 90° W 0°

Lat and Long Distances Latitude Longitude 69.13 miles (111.23 km) between each degree of latitude Longitude Varies by latitude 69 miles at equator only 59.9 miles at 30° 34.6 miles at 60°

Lat and Long estimation Latitude Can be estimated using the north star (Polaris), or Southern Cross Longitude Very tricky 1700’s difference between fixed clock and ship clock

TIME ZONES International Date Line SEPARATES ONE DAY FROM THE NEXT WHERE THE NEW DAY STARTS ANY LOCATION EAST OF OUR TIME ZONE UP TO 180° E IS AHEAD OF US ANY LOCATION WEST OF US UP TO THE DATE LINE (180°) IS BEHIND US Earth’s rotational speed is approximately 15° longitude/hour So 24 time zones

Time Zones

Keeping Time UTC or Z time DST New DST Indiana? London 5 hours ahead 6 on ST DST New DST Not in Arizona, Hawaii Indiana? Now observes DST

Map Projections Graticule → flat sheet of paper 3D to 2D distortion in 4 main properties major – pertains to all areas conformality (shape) equivalence (area & scale) minor – pertains to only 1 or 2 points equidistant (distance) azimuthal (direction)

Shape vs Area Conformality (shape) Equivalence (area) retention of correct angles requirements meridians & parallels cross at right angles misleading small areas VS large areas Equivalence (area) is lost Equivalence (area) unit area on map = same square unit on globe surface characteristics right angle crossing is lost shape distorted

Minor Properties Equidistant (distance) equivalence (area) is lost measure from center others area are incorrect (significant amount) equivalence (area) is lost DO NOT measure distance on a map showing a large area unless it is equidistant

Minor Properties and Other Azimuthal (direction) true directions from 1 central point others inaccurate can preserve 1 other property Other Compromise does not preserve any of the 4 main properties

Map Projections 4 general classes planar (azimuthal) cylindrical Conic oval and miscellaneous

Planar Projections (Azimuthal) Flat sheet of paper @ pole – polar aspect (simplest); least distortion @ mid-latitude – oblique aspect; @ equator – equatorial aspect Azimuthal projection air navigational hemispheres No (minimal) modifications

Lambert Azimuthal Equal Area Map large ocean areas SOURCE: Peter H. Dana, Department of Geography, University of Texas at Austin, 1995

Oblique Aspect Orthographic Projection Perspective views of hemispheres. SOURCE: Peter H. Dana, Department of Geography, University of Texas at Austin, 1995

Cylindrical Projections Tangent to line(s) on sphere normal @ equator Characteristics meridians do not converge at poles space parallels further apart smaller area – shape preserved Uses atlases map of the world

Behrmann Cylindrical Equal-Area SOURCE: Peter H. Dana, Department of Geography, University of Texas at Austin, 1995

Peters Projection SOURCE: Peter H. Dana, Department of Geography, University of Texas at Austin, 1995

Mercator Projection Marine navigation rhumb line

Miller Cylindrical Projection Avoids scale exaggerations of the Mercator shape & area distorted true direction along equator SOURCE: Peter H. Dana, Department of Geography, University of Texas at Austin, 1995

Conic Projections Cone enveloped around sphere normal – cone is tangent along a chosen parallel Area and shape preserved Simple Conic & Polyconic Uses: areas w/ east-west extent National Atlas of the United States of America

SOURCE: Peter H. Dana, Department of Geography, University of Texas at Austin, 1995

Conic Polyconic

Albers Equal Area Conic SOURCE: Peter H. Dana, Department of Geography, University of Texas at Austin, 1995

Miscellaneous Projections Unprojected Maps distortion scale, distance, area, & shape increases toward the poles

N. America: Unprojected Latitude and Longitude SOURCE: Peter H. Dana, Department of Geography, University of Texas at Austin, 1995 N. America: Unprojected Latitude and Longitude World: Unprojected Latitude and Longitude SOURCE: Peter H. Dana, Department of Geography, University of Texas at Austin, 1995

Choosing a Map Projection 1st step is to determine: location size shape These 3 determine where the area to be mapped falls in relation to the projections distortion country in the tropics – cylindrical projection country in the temperate zone – conical projection polar area – planar projection

Choosing a Map Projection (2) These global zones map into the areas in each projection where distortion is lowest: Cylindricals are true at the equator and distortion increases toward the poles. Conics are true along some parallel somewhere between the equator and a pole and distortion increases away from this standard. Planar are true only at their center point, but generally distortion is worst at the edge of the map. Can make other modifications