Geography Notes 01-04-12

7/28/2019 Geography Notes 01-04-12

1/29


2/29

Portraying Earth

The Nature of Maps

Map Scale

Map Essentials

The Role of Globes

Map Projections

Families of Map Projections Isolines

2 2011 Pearson Education, Inc.


3/29


4/29

The Nature of Maps

2-dimensionalrepresentation of

Earths surface

Show 4 key properties

of a region

Size

Shape

Distance

Direction

Maps are imperfect, since

Earth is a sphere


Figure 2-2b


5/29

Map Scale

Maps are usually smaller thanthe area they represent

Map scales are necessary to

understand realistic distances

on map

Scale is relationship between

area on map and area on

Earth

Three primary types Graphic

Fractional

Verbal


Figure 2-3


6/29

Map Scale

Large versus small map scales


Figure 2-4


7/29

Map Essentials

Need several propertiesof maps to help with

interpretation: Title

Date

Legend

Scale

Direction

Location Data Source

Map Projection


Figure 2-5


8/29

The Role of Globes

Advantages of Globes Maintains correct geographic

relationships between points

Can accurately represent spatial

relationships between points onEarth

Disadvantages of Globes Only can see a hemisphere at a

time

Large and bulky

Cannot contain much detail


Figure 2-6


9/29

Map Projections

Challenge of the cartographer (mapmaker) Combine geographic exactness of globe with convenience of

flat map

Definition of map projection

Principle behind map projections

Two primary types Equivalentratio of areal size on map and Earth is the same

Conformalshape of locations on the map is the same as on

Earth



10/29

Map Projections

Equivalence versus conformality dilemma


Figure 2-10


11/29

Families of Map Projections

Cylindrical Projections

Wrap the globe in a

cylinder of paper

Paper tangent to Earth

at equator

Conformal projection

Mercator projection is

most famous


Figure 2-7


12/29


Plane Projections

Project globe onto a

paper that is tangent to

globe at some point

Displays onehemisphere well

Equivalent projection

An example is an

orthographic planeprojection (Figure 2-13)


Figure 2-9


13/29


Conic Projections

Project the map onto a

cone tangent to or

intersecting the globe

Principal parallel

Good for mapping

small areas on Earth

Impractical for global

mapping


Figure 2-8


14/29


Pseudocylindrical

Projections

A mix of conformal and

equivalent

Central parallel and

meridian cross at right

angles

Oval shaped; distortion

increases as you moveaway from the center


Figure 2-11


15/29


Interrupted Projections

Minimize distortion

Discontinuous map,

shapes and sizes

maintained

Typically oceans are

distorted; land masses

maintain original

shape and size Goodes projection


Figure 2-14


16/29

Isolines

Definition

Many types

Isobar: line of constant

pressure

Isotherm: line of constant

temperature

Isohyet: line of constant rain

Isoamplitude: line of

constant wave amplitude

Construction steps/rules


Figure 2-16


17/29

Isolines


800

700600 500 400

300


18/29

Isolines

Topographic Maps

Show elevation

contours

Contour lines

Lines closer together

represent steeper

terrain

Often used in

geography


Figure 2-15


19/29

Isolines

Topographic Maps

Show elevation

contours

Lines closer together

represent steeper

terrain

Often used in

geography


Figure 2-15


20/29

GPSGlobal Positioning System

Global navigation satellite

system for determining

location on Earths

surface Wide Area Augmentation

System (WAAS)

Continuously Operating

GPS Reference Stations(CORS)


Figure 2-19


21/29

Remote Sensing

Measurement by a devicenot in contact with Earths

surface

Common types include: Aerial Photographs

Orthophoto maps

Visible Light and Infrared

(IR) Scanning Thermal IR scanning

Radar and Sonar

Many others


Aerial PhotographyFigure 2-20


22/29

Remote Sensing

Orthophoto maps

Photographic maps that

are multicolored and

distortion free

Useful in low-lying coastal

regions to show marsh

topography


Figure 2-21


23/29

Remote Sensing

Visible light and IR

scanning

Based off of visible light and

IR part of electromagnetic

spectrum (Figure 2-22)

Shows false color


Figure 2-23Figure 2-22


24/29

Remote Sensing

Radar Imagery

Radio Detection and Ranging

Useful for identifying atmospheric moisture

Sonar Imagery Sound Navigation and Ranging

Permits underwater imaging

Thermal IR scanning

Scans in the thermal IR part of spectrum

Shows images based on temperature

Often utilized in meteorology


GIS G hi I f ti


25/29

GISGeographic Information

Systems

Computer systems used to

analyze and display spatial

data

Layers of data used inmapping

Requires high powered

computing to process

multiple maps


Figure 2-29


26/29

Tools of the Geographer

Vast array of maps, remotely sensed satellite

imagery, and computer applications

Difficult to determine the best way to use all of

this information Some tools better at identifying features on

Earth than others

Ultimate goal: To better understand Earth.



27/29

Summary

Maps are essential to portray features on Earths

surface

Need a map scale to identify how a map relates

to the actual surface features on Earth Many other map properties are essential to

interpreting a map

Globes have several advantages and

disadvantages

Representing Earth in 2 dimensions can be done

through map projections



28/29

Summary

Many different map projections exist

Dilemma of equivalent versus conformal

Plotting isolines on a map can help with

interpretation of features on the map The global positioning system (GPS) helps to

identify location on Earths surface

Remote sensing is a measurement of Earthssurface from a system not on Earths surface



29/29

Summary

Many different remote sensing instruments

exist, including satellite, radar, and sonar

GIS are computer systems used to analyze and

display spatial data, often in layers The geographer has many tools, but the

ultimate goal is To better understand Earth.


Documents

Geography Notes 01-04-12