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

MapDefined as: a graphic representation of the real world

symbolizes the features or conditions of these locations

Always abstraction of reality3D to 2 D???

Latitude & Longitude

The Map Coordinate System

Direction on a Map: Map Coordinate System

Latitude/longitudepinpointing a unique location on the Earth’s surface

All maps show same latitude and longitude for a particular point on the Earth’s surface

LatitudeDistance in degrees north and south of the equatorMeasured 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 latitude90°N and 90°S (1/4 of 360°)

90°N

LongitudeDistance in degrees east and west of the prime meridianMeasured by meridiansMeridians get closer together the further away from the equatorUsed for defining 24 time zones

Prime Meridian

Starting line for longitudinal systemPasses through Greenwich, England0° longitude180° is furthest meridian (360/2)

International Date Line

Coordinate SystemDegrees divided into minutes and seconds

5°20‘45“ 5 degrees, 20 minutes, 45 seconds

Latitude1° = 111 km

LongitudeNo set number of km1° = 4 minutes of time15 ° = 1 hour

Read latitude number FIRST, then longitude!!!

Finding Latitude in the NORTHERN HEMISPHERE

Angle of Polaris (North Star) = angle of latitude

Practice with PolarisWhat is the angle of Polaris at the following points?

ABCDE

What happens to the altitude of Polaris as you move from

A to DB to C

Finding Polaris

Practice with PolarisIf Polaris is 40° above the horizon, what is your

LatitudeLongitude

If you can’t see Polaris above the horizon, where are you?

Great Circles

Great circlesPlane passes through the center of the sphere

Small circlePlane does not pass through center of sphere

EquatorGreat circle

Each meridianHalf a great circle

Great Circle RouteShortest distance between two points on a sphereUsed for airplane travel

Time Zones

Earth’s 24 Time Zones

Why 24?24 hours to rotate on its axis

15° (longitude) each

Time zones adjustedLocal areas same Large areas divided

US has 6 time zones

International Date Line180° meridian (longitude)Traveling west, advance a dayTraveling east, lose a day

Sun

Mon

Parts of a Map

Scales, Legends & Symbols

Map Scalescompares 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 ScalesVerbal –

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 distance1 : 100 = 1 unit of length on the map = 100 times the same unit on the map

LegendExplain what the symbols on a map represents

Topographic MapShow changes in elevation of the Earth’s surface, as well as, other features

Mountains, rivers, forests, bridges

Contours LinesConnect points of equal elevation

Fields & IsolinesField

Region in which a similar quantity can be measured at every point or location

IsolineLines that connect points of equal field value

Contour IntervalDifference between contour lines

4400-4000 = 400 ft

Index contour = elevation written

Reading Topographic Maps

The RulesMap scaleContour intervalDirection of stream flowSteepest sectionBenchmarkDepressionIslandsHighest 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 depressionGentle slopeSteep slope

Topographic Profile

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

ReliefDifference in elevation

Between any two pointsHighest elevation & lowest elevation

Relief Map

indicates elevation Shading, colors

topographic mapSpecial type of relief map

Calculating GradientsChange in the steepness of the slopeChange 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 areaSmaller area, more accurate

Convert 3D to 2D with Map Projections

Map ProjectionsRepresentation of curved Earth shown on a flat surfaceMost accurate where paper touches globe3 basic types

Cylindrical (Mercator)Planar (Gnomonic)Conic

Mercator

Cylindrical projectionShows the whole world on a continuous map (except polar regions)Parallel latitude and longitude linesMost accurate around the equator

Or wherever paper cylinder touches globe

Distorted distances and shapesHigh latitudes are inaccurate

Conic ProjectionProject points and lines from a globe onto a coneCone touches globe at a particular line of latitudeOnly used for small areasMost accurate projection - nearly correct in all respects Useful in making

Topographic mapsRoad mapsWeather maps

Gnomonic Project points and lines from a globe onto a piece of paper touching the globe at a single pointshows shortest route between two points on the Earthuseful for planning airplane flights and ocean tripsproblem – directions and distances are distorted

Great Circles

Great circlesPlane passes through the center of the sphere

Small circlePlane does not pass through center of sphere

EquatorGreat circle

Each meridianHalf a great circle

Great Circle RouteShortest distance between two points on a sphereUsed for airplane travel

Special Projections

RobinsonGoode’s

Robinson ProjectionCombines the good parts of several other map projectionsMinimal distortion of most of the Earth's land masses

Antarctica & northernmost landmasses are still greatly distorted

Commonly considered the best map Commonly considered the best map representation of the size and shape of the representation of the size and shape of the Earth's landformsEarth's landforms

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

Remote Sensing

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

The Electromagnetic SpectrumArrangement of electromagnetic radiation according to wavelengthsAll travel at the speed of light in a vacuum

300 000 km/s

WavelengthDistance between two successive peaksGamma shortestRadio longest

FrequencyNumber of waves that pass a point per secondGamma = highestRadio = lowest

SatellitesLandsatTopex/poseidon

Global Positioning System (GPS)Sea Beam

Remote Sensing Techniques

Landsat Satellites

Receives reflected wavelengths of energy emitted by Earth’s surface

VisibleIR (infrared)

Used forEarth’s features (rivers, forests…)Movement of Earth’s platesEarthquakesPollution

Topex/Poseidon Satellite

Uses radar to map features on the ocean floor

Tidal currentsGlobal ocean currents

Uses echo to determine distance

Time from sent signal to received signal

The Geographic Positioning System (GPS)Radio-navigation system of 24+ satellitesHigh frequency microwaves Determine exact position on the Earth

Precise latitude & longitude

Other uses includeDetect earthquakesCreate mapsAirplane/ship navigationTrack 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 BeamUses sonar from a ship to map the ocean-floor features