Latitude and Longitude

1. Latitude and Longitude • Latitude • 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

2. 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

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

4. Lat and Long Distances • Latitude • 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°

5. 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

6. 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

7. Time Zones

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

9. 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)

10. Conformality (shape) 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 Shape vs Area

11. Minor Properties • Equidistant (distance) • 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

12. 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

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

14. 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

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

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

17. 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

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

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

20. Mercator Projection • Marine navigation • rhumb line

21. 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

22. 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

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

24. Conic Polyconic

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

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

27. 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

28. 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

29. 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