Models of the Earth - Mapping
- 1. Models of the Earth
- 2. Finding Locations on the Earth Globe: spherical representation of the earth’s surface No corners, no top, no bottom as reference points Use rotation of Earth on it’s axis as reference point North and South Geographic Poles Equator located halfway between poles
- 3. Latitude Parallels: set of circles around the Earth going east to west and separated north to south
- 4. Latitude Latitude: the angular distance north or south of the equator - equator is zero degrees - measured in degrees from equator
- 5. Parts of Latitude 0o to 90o from equator to North pole – labeled N 0o to 90o from equator to South pole – labeled S Each degree broken into 60 parts called minutes
- 6. Parts of Latitude Degrees symbol = o Example: 45o says 45 degrees Minutes symbol = ‘ Example: 30’ says 30 minutes Seconds symbol = “ Example 23” says 23 seconds
- 7. Parts of Latitude Washington D.C. 38o53’51”N reads 38 degrees 53 minutes 51 seconds north (Image rounded to degrees)
- 8. Longitude Meridians: intersections to determine east-west locations on latitude Measured in degrees, minutes, and seconds too Prime meridian agreed to be 0o – runs through Greenwich, England
- 9. Longitude Longitude: the angular distance east or west of the prime meridian - prime meridian is zero degrees - - measured in degrees from prime meridian
- 10. Parts of Longitude 0o to 180o east of prime meridian – labeled E 0o to 180o west of prime meridian – labeled W Distance between degrees depends on location on Earth
- 11. Parts of Longitude Degrees symbol = o Example: 45o says 45 degrees Minutes symbol = ‘ Example: 30’ says 30 minutes Seconds symbol = “ Example 23” says 23 seconds
- 12. Parts of Longitude Washington D.C. 77o0’33”W reads 77 degrees 0 minutes 33 seconds west (Image rounded to degrees)
- 13. Great Circles Great circle: any circle that divides the globe into halves Any circle formed by two meridians on opposite sides of globe
- 14. Finding Direction Magnetic compass: indicates direction by responding to earth’s natural magnetic properties Earth’s imaginary magnet is at an angle to the earth’s axis of rotation
- 15. Finding Direction The points on the earth’s surface just above the poles of the imaginary magnet are called geomagnetic poles Geomagnetic and geographic poles are in different locations
- 16. Finding Direction Magnetic declination: the angle between the direction of the geographic pole and the direction which the compass points
- 17. Magnetic pole shift http://www.youtube.com/watch?v=Rmc 8U9zWN00
- 18. Finding Direction The geographic north pole is called true north.
- 19. Mapping the Earth’s Surface Cartography: the science of map making Map: a flat representation of the earth’s curved surface
- 20. Map Projections A flat map surface that covers a 3D curved surface is called a map projection
- 21. Map Projections Mercator projection: wrapping a cylinder of paper around a lighted globe
- 22. Map Projections Gnomonic projection (polar): a sheet of paper only touches a lighted globe at one point
- 23. Map Projections Gnomonic projection Helpful for air navigation cause a straight line indicates part of a great circle
- 24. Map Projections Conic Projection: a paper cone placed over a lighted globe so the axis of the cone aligns with the axis of the globe Cone touches the globe along one parallel of latitude
- 25. Map Projections Polyconic projection: a series of conic projections used to map a number of neighboring areas
- 26. Reading a Map Symbols needed to read a map Legend: a list of symbols and their meanings Direction: usually indicates north somewhere on map Scale: indicates the relationship between distance as shown on map and actual distance
Editor's Notes
- #20: Hard to put 3D onto 2D surface Larger the area, the larger the distortion Like an orange peel
- #22: Disadvantages: poles distorted cause meridians suppose to come together Places far away from equator appear larger that true size cause of distortion Advantages: all compass directions appear in straight lines with 4 points on compass Latitude and longitude easily measured with a ruler cause parallels and meridians are shown clearly instead of meridians changing when moving away from equator Valuable navigation tool
- #23: Advantages: little distortion cause only at one point great help to navigator routing air travel Disadvantages: unequal spacing between parallels a straight line drawn on these projections show a great circle and this is the shortest distance between two points on a globe