GEO 101, January 16, 2014, Latitude and Longitude Finding your way … How geographers locate where things are… Most common locational system Best reference points are ends of rotational axis Latitude and Longitude Measures angular distance in degrees, not distance in miles or km Basic geometry: circle has 360 degrees Babylonians (≈600 BC) chose the number 360. The reason is that their number system was based on 60. To compare, we base our number system on 10. For us, 10 is a nice, round number and we find it very convenient to count in multiples of 10. But the Babylonians liked 60. LATITUDE Midway between N & S pole is Equator = 0° 90° N 0° 90° S 1 Latitude of Mobile ≈ 30° 42’ N. Parallels of latitude measure the angular distance (degrees) north or south of the Equator. Expressed in degrees, minutes, & seconds 60 minutes in 1 degree 60 seconds in 1 minute The lines themselves run east - west like the rungs on a ladder Find distance in miles between Latitude can be used to approximate Mobile and the Galapagos Islands, distances based on following: which is almost due south of Mobile 360° in a circle Galapagos 0° 10’ S Mobile 30° 42’ N ≈ 25,000 miles around earth 25,000 miles / 360° ≈ 69 miles in 1° Difference 30° 52’ or 30 + 52/60 degrees = 30.87° One degree of latitude always ≈ 69 miles This is true because parallels of latitude 30.87° x 69 mi/degree = 2130 miles stay same distance apart LONGITUDE Arbitrary starting place at Greenwich (London), England 180° = International Date Line East West N P 0° = Prime Meridian 2 One degree of longitude ONLY EQUALS 69 Meridians of longitude measure the miles, at the Equator. angular distance (degrees) Longitude lines do not stay the same east or west of the Prime Meridian. distance apart. They are closer together near the poles than at the Equator. Expressed in degrees, minutes, and seconds 60 minutes in 1 degree 60 seconds in 1 minute Lines of longitude run north - south Longitude of Mobile ≈ 88° 3’ W. Geographic Latitude Longitude Grid or GRATICULE Graticule: the pattern of parallels and meridians on Location of any place on earth can be expressed in a globe latitude / longitude. 1. Parallels are straight east-west lines Examples: Mobile, 30° 42‘ N, 88° 03‘ W 2. Meridians are straight north-south lines Sydney, Australia, 33° 55‘ S, 151° 17‘ E 3. Parallels are equally spaced and never intersect Anchorage, Alaska, 61° 12‘ N, 149° 48‘ W one another Must include designation N, S, E, or W 4. Meridians are farthest apart at the Equator and come together at the poles 5. Parallels and Meridians cross at right angles 3 What is the latitude/longitude of the exact opposite place LONGITUDE on Earth to Sydney, Australia, 33° 55‘ S, 151° 17‘ E 90° N 180° Sydney LATITUDE 151° 17’ E 33° 55’ N N P 0° West East Sydney 33° 55‘ S 29° W 90° S 0° Where is 34° N, 29° W ? Earth-sun Relations Sydney, Australia 34º S, 151° E Sunlight and darkness pattern on June Solstice June Solstice Summer in N. Hemisphere 66.5°N 23.5°N 4 December Solstice Comparison of Winter in N Hemisphere day and night at Anchorage, Alaska, 61°N (A) & Spokane, Washington, 48°N () on the 23.5°S December Solstice. 66.5°S Sunlight and darkness pattern on Vernal Equinox Spring and Fall Equinox Equal day and night everywhere March Equinox You should know the names of these parallels, their latitudes, and where the vertical rays of the sun strike on the June December June and Solstice Solstice December solstices and on the March and September Sept. Equinox Equinoxes. 5 Today’s classwork: on your map: 1. First figure out the degrees between each line, the map covers the entire world, and the distance between lines is the same in degrees. 2. Label the Equator and the Prime Meridian 3. Put the correct value on each latitude line 4. Put the correct value on each longitude line 5. Draw in the Tropic of Cancer, Tropic of Capricorn, Arctic Circle, Antarctic Circle 6. Locate the following four places on your map 7. When you complete this, please help someone around you who is struggling with it. 0°S, 88°W 21°S, 14°E 46°N, 116°W 67°N, 51°W 6.