Latitude And Longitude PrimerPresentation Transcript
Latitude and Longitude A Primer
Latitude and Longitude A coordinate system for locating positions on the Earth’s surface. Units measured in Degrees, minutes, seconds In computer cartography and GIS, units are often decimal degrees (e.g., 34.5o for 34o 30’) Latitude lines set up differently than Longitude lines Many climatic phenomena vary by latitude Tropics, Subtropics, Midlatitudes, SubArctic and Arctic (Subantarctic and Antarctic in the south) Directional Terminology Equatorward, Poleward
Latitude Measured in Degrees Measure distances North or South of the Equator Values range from 0o – 90o North or South (ex. 34oN) Positive or Negative on computer maps (ex. +34o) Fixed References Poles (Polaris; North Star; 90oN) Equator (midway between poles; 0o) Angles measured up from the plane of the equator Rotating angle about the earth’s axis produces Lines of Latitude Parallels (Lines of Latitude never touch each other) Form concentric circles around the poles
Take the time to learnthese zones and theirlatitudinal ranges:
Longitude Measured in Degrees Measures distances East and West of the Prime Meridian Values range from 0o – 180o East or West (ex. 171oW) Positive or Negative (ex. -171o) Fixed References The Prime Meridian (Greenwich England) Arbitrary – no celestial reference Angles measured in the equatorial plane, as angular distance from Prime Meridian Arcs swept from this angle toward either pole are Lines of Longitude Meridians Meet at the poles
Coordinates Locations are determined by both a latitude and longitude Example: Mount Diablo Latitude: 37° 52′ 54″ N Longitude: 121° 54′ 51″ W The combination of both the latitude lines and longitude lines on a map or globe is called the graticule.