The Science of Map Making

 Separates the Earth into 2 halves a) Northern Hemisphere b) Southern Hemisphere

 Lines running parallel to equator  Distance in degrees North or South of equator a) equator ° b) poles °  Each degree represents 111 km  Finding distance: Earth is divided into 360° Circumference = 40,000 km Distance = 40,000 km/360°  For precision use minutes and seconds  Minutes = ‘ 1 min = 1.85 km ( 111km/60)  Seconds = '‘ 1 sec = 0.03 km (111 km/3600)

 Also called Meridians  Gives positions east and west of the prime meridian Prime Meridian goes through Greenwich England Prime Meridian = 0° Longitude  Lines are not parallel; they are semicircles  International Date line occurs when East meets West

1) Degrees of latitude are consistent Degrees of longitude are not consistent 2) Degrees of longitude vary with location 3) Degrees of longitude converge at the poles ( 1 ° varies with 111 km ) To precisely locate a known site you need both latitude and longitude EX: 36.2°N 54.3°W Lat, Long

 Time Zones a) Earth is divided into 24 time zones because it takes the Earth 24 hours to rotate b) Each time zone is 15° wide  Calendar Dates a) International Date Line = 180° meridian - this serves as the transition for days b) traveling West – you go forward in time c) traveling East - you go backward in time

Mercator Projections  Parallel lines of latitude and longitude  Land masses are exaggerated - shapes are correct - areas are distorted  Used for navigation of planes and ships

Conic Projections  Projects points and line from a globe onto a cone  Cone touches at a particular line of latitude  Little distortion along line  Distortion occurs near top and bottom  Used for mapping small areas

 Gnomonic Projections  Made by projecting points and lines onto paper that touches the globe in a single point  Distorts direction and distance between landmasses  Used to represent circular routes  Used in plotting long distance air or sea trips

Topographic Projections  Shows changes in elevation  Contour lines- connects points of equal distance; they never cross each other  Contour intervals- difference between side-side elevations  Index contours – numerical representation of elevation, can be (+) or (-)  Depression contours- represents volcanoes, mines, etc. Hachures- drawn at right angles to contour lines and point toward lower elevations

 Map Legend- represents human and natural objects (look at page 35)  Map Scales- ratio between distance on map and actual distance  3 Types of map scales: 1) Verbal 2) Graphic 3) Fractional

 Remote Sensing—process of collecting data about Earth from above  Background Information: 1) Electromagnetic Spectrum Energy has both electric and magnetic properties (Visible light,Gamma Rays,X Rays,UV Rays, Infrared, Radio Waves and Microwaves) Gamma Rays have the highest frequency and energy Radio Rays have the lowest frequency and energy Speed of Light = 3 x 10 6 m/s

Landset Satellites  Receives reflected visible and infrared energy  Used to study Earth’s plates, rivers, earthquakes and pollution

Topex/Poseidon Satellites  Radar uses high frequency signals from satellite to ocean floor  Receiver picks up the echo  Used to study tidal changes and ocean currents

Global Positioning System (GPS)  24 Satellites are used  Receiver calculates precise latitude and longitude  Used by plane, ship, earthquakes, maps, tracking wildlife, hikers, etc.

Sea Beam  Similar to Topex/Poseidon  Radar located on ship  Uses sonar and sound waves are used to measure objects underwater -sound waves are sent from ship to ocean -receiver picks up echo -computer calculates distance using speed of sound in water (1500 m/s) and time it takes for sound to be reflected  Used by fishing fleets, deep sea drilling operations, oceanographers, volcanologists and archaeologists