1. Chapter 2: Portraying Earth
McKnight’s Physical Geography: A Landscape Appreciation,

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Portraying Earth
The Nature of Maps
Map Scale
Map Essentials
The Role of Globes
Map Projections
Families of Map Projections
Isolines
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Portraying Earth
GPS—Global Positioning System
Remote Sensing
GIS—Geographic Information Systems
Tools of the Geographer
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The Nature of Maps
2-dimensional representation of Earth’s surface
Show 4 key properties of a region
Size
Shape
Distance
Direction
Maps are imperfect, since Earth is a sphere
Figure 2-2b
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Map Scale
Maps are always smaller than the 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
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6. Map Scale
Large versus small map scales

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Map Essentials
Need several properties of maps to help with interpretation:
Title
Date
Legend
Scale
Direction
Location
Data Source
Map Projection
Figure 2-5
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The Role of Globes
Advantages of Globes
Maintains correct geographic relationships between points
Can accurately represent spatial relationships between points on Earth
Disadvantages of Globes
Only can see a hemisphere at a time
Large and bulky
Cannot contain much detail
Figure 2-6
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9. Globe properties Parallels of latitude Meridians of longitude
parallel to each other
decrease in length closer to the poles
Meridians of longitude
converge at the poles
equal length (1/2 equator)
Both: intersect at right angles

11. Map Projections
Process of transferring the spherical earth onto a 2-dimensional surface.
Estimate size and shape of earth in 3 dimensions
Properties of map projections:
equal area (area)
conformal (shape)
equidistant (distance)
azimuthal (direction)
Types of map projections:
cylindrical
conic
azimuthal (planar)

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Map Projections
Equivalence versus conformality dilemma
Figure 2-10
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13. 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
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15. Map Projections

16. Mercator projection

17. Transverse Mercator

18. Families of Map Projections
Plane Projections
Project globe onto a paper that is tangent to globe at some point
Displays one hemisphere well
Equivalent projection
An example is an orthographic plane projection (Figure 2-13)
Figure 2-9
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19. Families of Map Projections
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
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20. Families of Map Projections
Pseudocylindrical Projections
A mix of conformal and equivalent
Central parallel and meridian cross at right angles
Oval shaped; distortion increases as you move away from the center
Figure 2-11
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21. Families of Map Projections
Interrupted Projections
Minimize distortion
Discontinuous map, shapes and sizes maintained
Typically oceans are distorted; land masses maintain original shape and size
Goode’s projection
Figure 2-14
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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
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Isolines
800
600
500
700
400
300
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Isolines
Topographic Maps
Show elevation contours
Contour lines
Lines closer together represent steeper terrain
Often used in geography
Figure 2-15
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Isolines
Topographic Maps
Show elevation contours
Lines closer together represent steeper terrain
Often used in geography
Figure 2-15
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26. GPS—Global Positioning System
Global navigation satellite system for determining location on Earth’s surface
Wide Area Augmentation System (WAAS)
Continuously Operating GPS Reference Stations (CORS)
Figure 2-19
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Imagine you are somewhere in the United States and you are TOTALLY lost -- for whatever reason, you have absolutely no clue where you are.
You find a friendly local and ask, "Where am I?" He says, "You are 625 miles from Boise, Idaho."
This is a nice, hard fact, but it is not particularly useful by itself. You could be anywhere on a circle around Boise that has a radius of 625 miles, like this:
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You ask somebody else where you are, and she says, "You are 690 miles from Minneapolis, Minnesota."
Now you're getting somewhere. If you combine this information with the Boise information, you have two circles that intersect.
You now know that you must be at one of these two intersection points, if you are 625 miles from Boise and 690 miles from Minneapolis.
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If a third person tells you that you are 615 miles from Tucson, Arizona, you can eliminate one of the possibilities, because the third circle will only intersect with one of these points. You now know exactly where you are -- Denver, Colorado.
This same concept works in three-dimensional space, as well, but you're dealing with spheres instead of circles.
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30. Remote Sensing
Measurement by a device not in contact with Earth’s surface
Common types include:
Aerial Photographs
Orthophoto maps
Visible Light and Infrared (IR) Scanning
Thermal IR scanning
Radar and Sonar
Many others
Aerial Photography—Figure 2-20
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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
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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 2-23
Figure 2-22
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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
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34. GIS—Geographic Information Systems
Computer systems used to analyze and display spatial data
Layers of data used in mapping
Requires high powered computing to process multiple maps
Figure 2-29
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35. 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.”
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Summary
Maps are essential to portray features on Earth’s 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
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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 Earth’s surface
Remote sensing is a measurement of Earth’s surface from a system not on Earth’s surface
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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.”
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