Cartography Mapping the World

Cartography The art (science) of map making

Cartographer One who makes or studies maps

Main Goal of Maps To communicate information

Map Defined as: a graphic representation of the real world symbolizes the features or conditions of these locations Always abstraction of reality 3D to 2 D???

The Map Coordinate System Latitude & Longitude The Map Coordinate System

Direction on a Map: Map Coordinate System Latitude/longitude pinpointing a unique location on the Earth’s surface All maps show same latitude and longitude for a particular point on the Earth’s surface

Latitude Distance in degrees north and south of the equator Measured by parallels Imaginary lines that circle the world from east to west parallel of the equator Equator = 0°latitude North Pole and South Pole = Points of latitude 90°N and 90°S (1/4 of 360°)

90°N

Longitude Distance in degrees east and west of the prime meridian Measured by meridians Meridians get closer together the further away from the equator Used for defining 24 time zones

Prime Meridian Starting line for longitudinal system Passes through Greenwich, England 0° longitude 180° is furthest meridian (360/2) International Date Line

Coordinate System Degrees divided into minutes and seconds Latitude 5°20‘45“ 5 degrees, 20 minutes, 45 seconds Latitude 1° = 111 km Longitude No set number of km 1° = 4 minutes of time 15 ° = 1 hour Read latitude number FIRST, then longitude!!!

Finding Latitude in the NORTHERN HEMISPHERE Angle of Polaris (North Star) = angle of latitude

Practice with Polaris What is the angle of Polaris at the following points? A B C D E What happens to the altitude of Polaris as you move from A to D B to C

Finding Polaris

Practice with Polaris If Polaris is 40° above the horizon, what is your Latitude Longitude If you can’t see Polaris above the horizon, where are you?

Great Circles Great circles Small circle Plane passes through the center of the sphere Small circle Plane does not pass through center of sphere

Equator Great circle Each meridian Half a great circle

Great Circle Route Shortest distance between two points on a sphere Used for airplane travel

Time Zones

Earth’s 24 Time Zones Why 24? 15° (longitude) each 24 hours to rotate on its axis 15° (longitude) each

Time zones adjusted Local areas same Large areas divided US has 6 time zones

International Date Line 180° meridian (longitude) Traveling west, advance a day Traveling east, lose a day Mon Sun

Scales, Legends & Symbols Parts of a Map Scales, Legends & Symbols

Map Scales compares distance on a map with actual distance of section of the Earth’s surface the smaller the map representation (piece of land), the larger the scale

Large Scale -less area -more detail Small Scale -more area -less detail

Large vs Small Scale Bigger the number = small ratio = smaller the scale because more area is covered

A C B

Types of Scales Verbal – Graphic – Numerical (fractional)– Word statement “1 centimeter = 50 kilometers” Graphic – line is divided into equal parts and marked off into units of equal length Numerical (fractional)– a fraction/ratio is used to show what part of true distance the map distance really represents 1/ 100 = any distance is one hundredth of the true distance 1 : 100 = 1 unit of length on the map = 100 times the same unit on the map

Legend Explain what the symbols on a map represents

Topographic Map Show changes in elevation of the Earth’s surface, as well as, other features Mountains, rivers, forests, bridges

Contours Lines Connect points of equal elevation

Fields & Isolines Field Isoline Region in which a similar quantity can be measured at every point or location Isoline Lines that connect points of equal field value

Contour Interval Difference between contour lines Index contour = elevation written Difference between contour lines 4400-4000 = 400 ft

Reading Topographic Maps

The Rules Map scale Contour interval Direction of stream flow Steepest section Benchmark Depression Islands Highest elevation

X = Benchmark – scientifically determined elevation “V” contour lines point to origin of river (point “up” stream)

Water flows down hill V points up hill

Closed depression Gentle slope Steep slope

Topographic Profile Shows the shape of the land along one part of the map

Relief Difference in elevation Between any two points Highest elevation & lowest elevation

Relief Map indicates elevation topographic map Shading, colors Special type of relief map

Calculating Gradients Change in the steepness of the slope Change in elevation ÷ distance

Making Maps

Problem… Earth is a sphere! Something (shape, distance or direction) is ALWAYS distorted

Accuracy Depends on the size of the area Smaller area, more accurate

Convert 3D to 2D with Map Projections

Map Projections Representation of curved Earth shown on a flat surface Most accurate where paper touches globe 3 basic types Cylindrical (Mercator) Planar (Gnomonic) Conic

Mercator Cylindrical projection Shows the whole world on a continuous map (except polar regions) Parallel latitude and longitude lines Most accurate around the equator Or wherever paper cylinder touches globe Distorted distances and shapes High latitudes are inaccurate

Conic Projection Project points and lines from a globe onto a cone Cone touches globe at a particular line of latitude Only used for small areas Most accurate projection - nearly correct in all respects Useful in making Topographic maps Road maps Weather maps

Gnomonic Project points and lines from a globe onto a piece of paper touching the globe at a single point shows shortest route between two points on the Earth useful for planning airplane flights and ocean trips problem – directions and distances are distorted

Great Circles Great circles Small circle Plane passes through the center of the sphere Small circle Plane does not pass through center of sphere

Equator Great circle Each meridian Half a great circle

Great Circle Route Shortest distance between two points on a sphere Used for airplane travel

Special Projections Robinson Goode’s

Robinson Projection Combines the good parts of several other map projections Minimal distortion of most of the Earth's land masses Antarctica & northernmost landmasses are still greatly distorted Commonly considered the best map representation of the size and shape of the Earth's landforms

Goode’s oceans interrupted to show the continents true shape to continents

Collecting data about the Earth from far above the Earth’s surface Remote Sensing Collecting data about the Earth from far above the Earth’s surface

The Electromagnetic Spectrum Arrangement of electromagnetic radiation according to wavelengths All travel at the speed of light in a vacuum 300 000 km/s

Wavelength Distance between two successive peaks Gamma shortest Radio longest

Frequency Number of waves that pass a point per second Gamma = highest Radio = lowest

Remote Sensing Techniques Satellites Landsat Topex/poseidon Global Positioning System (GPS) Sea Beam

Landsat Satellites Receives reflected wavelengths of energy emitted by Earth’s surface Visible IR (infrared) Used for Earth’s features (rivers, forests…) Movement of Earth’s plates Earthquakes Pollution

Topex/Poseidon Satellite Uses radar to map features on the ocean floor Tidal currents Global ocean currents Uses echo to determine distance Time from sent signal to received signal

The Geographic Positioning System (GPS) Radio-navigation system of 24+ satellites High frequency microwaves Determine exact position on the Earth Precise latitude & longitude Other uses include Detect earthquakes Create maps Airplane/ship navigation Track wildlife

GPS satellites triangulate points on the Earth’s surface.

Using remote sensing satellites in space, the GPS system can locate points to within inches of its actual location.

Sea Beam Uses sonar from a ship to map the ocean-floor features