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

2. 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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3. Portraying Earth
• GPS—Global Positioning System
• Remote Sensing
• GIS—Geographic Information Systems
• Tools of the Geographer
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4. 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
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Figure 2-2b

5. 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
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Figure 2-3

6. Map Scale
• Large versus small map scales
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Figure 2-4

7. Map Essentials
• Need several properties
of maps to help with
interpretation:
– Title
– Date
– Legend
– Scale
– Direction
– Location
– Data Source
– Map Projection
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Figure 2-5

8. 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
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Figure 2-6

9. 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
– Equivalent—ratio of areal size on map and Earth is the same
– Conformal—shape of locations on the map is the same as on
Earth
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10. Map Projections
• Equivalence versus conformality dilemma
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Figure 2-10

11. 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
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Figure 2-7

12. 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)
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Figure 2-9

13. 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
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Figure 2-8

14. 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
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Figure 2-11

15. 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
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Figure 2-14

16. 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
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Figure 2-16

17. Isolines
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800
700
600 500 400
300

18. Isolines
• Topographic Maps
– Show elevation
contours
– Contour lines
– Lines closer together
represent steeper
terrain
– Often used in
geography
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Figure 2-15

19. Isolines
• Topographic Maps
– Show elevation
contours
– Lines closer together
represent steeper
terrain
– Often used in
geography
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Figure 2-15

20. 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)
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Figure 2-19

21. 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
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Aerial Photography—Figure 2-20

22. Remote Sensing
• Orthophoto maps
– Photographic maps that
are multicolored and
distortion free
– Useful in low-lying coastal
regions to show marsh
topography
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Figure 2-21

23. Remote Sensing
• Visible light and IR
scanning
– Based off of visible light and
IR part of electromagnetic
spectrum (Figure 2-22)
– Shows “false color”
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Figure 2-23
Figure 2-22

24. 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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25. 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
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Figure 2-29

26. 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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27. 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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28. 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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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.”
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