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Models of the Earth: Using and Interpreting Maps

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Title: Models of the Earth: Using and Interpreting Maps


1
Models of the Earth Using and Interpreting Maps
  • Finding Locations on Earth
  • Mapping the Earths Surface
  • Topographic Maps

2
Thought Question
  • What is the purpose of maps?
  • How are positions on planet Earth
    represented/located?
  • Explain how you would go about creating a map by
    hand. What kinds of tools would you need? What
    variables would you need to consider?

3
Objectives
  • Distinguish between latitude and longitude
  • Explain how latitude and longitude can be used to
    find a location on Earth
  • Explain how a magnetic compass can be used to
    find directions on Earth
  • Describe the characteristics and uses of three
    types of map projections
  • Define scale and explain how it can be used to
    find distance on maps
  • Explain how elevation and topography can be shown
    on a map
  • Interpret a topographic map

4
Why Maps?
  • For thousands of years, people have used maps
  • to define borders and to find places.
  • Cartography is the science of mapmaking.
  • Cartographers use an imaginary grid of parallel
    lines and vertical lines to locate points on
    Earth.
  • The equator circles Earth halfway between the
    north and south poles separating Earth into two
    equal halves called the northern hemisphere and
    the southern hemisphere.

5
Latitude
  • Parallels- imaginary circles running east/west on
    the globe determine how far north/south one is
    named because they parallel the equator
  • Latitude- the angular distance from north and
    south of the Equator measured in degrees (90
    intervals)
  • Latitudinal Great Circle- Equator is the only
    latitudinal great circle (any line that separates
    the earth into two equal parts)

6
Latitude
  • Latitude is thus measured from 0 at the equator
    to 90 at the poles.
  • Locations north of the equator are referred to by
    degrees north latitude (N).
  • Locations south of the equator are referred to by
    degrees south latitude (S).

7
Longitude
  • Meridians- lines running north/south on the
    globe, pole to pole determine how far east/west
    one is
  • Prime Meridian- the point 0 longitude runs
    through Greenwich, England
  • Longitude- the angular distance east or west of
    the Prime Meridian all measured from 0- 180
    east or west of the Prime Meridian
  • Longitudinal Great Circles- any two meridians
    running directly opposite (180) from one
    another bisect the globe

8
Longitude
  • Points west of the prime meridian are numbered
    from 0 to 180 west longitude (W).
  • Points east of the prime meridian are numbered
    from 0 to 180 east longitude (E).

9
Locating Places with Coordinates
  • Both latitude and longitude are needed to
    precisely locate positions on Earth.
  • For example, the location of New Orleans is
    2957N, 9004W.
  • Note that latitude comes first in reference to
    the coordinates of a particular location.

10
Assessment
  • Match the following terms with their definitions.
  • ___ latitude
  • ___ longitude
  • ___ prime meridian
  • ___ equator

D B A C
A. the reference point for longitude B. the
distance in degrees east or west of 0 C. the
reference point for latitude D. the distance in
degrees north or south of 0
11
Assessment
  • Identify whether the following statements are
    true or false.

false true false true
_______ A degree of longitude always represents
the same distance. _______ If you travel west
across the International Date Line, you advance
your calendar one day. _______ Lines of latitude
are not perfectly parallel to each
other. _______ When referencing a specific place
on Earth by its coordinates, latitude always
comes first.
12
Direction Finding
  • Geomagnetic Poles- the point above the earths
    poles where all magnetic lines converge
  • The earth behaves as a giant magnet with areas
    near the north and south pole acting as the ends
    of the magnet this affects compasses different
    amounts in different areas
  • Magnetic Declination- the angle between the
    direction of the earths geographic pole and the
    direction in which a compass needle points
  • True North- direction of the geographic north
    pole

13
Thought Question
  • Describe one type of map that you have seen or
    used. What symbols are used? How are land forms
    depicted? Name the type of map if you know it.
  • What fields of science use maps and what are the
    maps used for?
  • Compare and contrast magnetic north and true
    north.

14
Mapping The Earths Surface
  • Maps are flat models of a three-dimensional
    object, Earth.
  • All flat maps distort to some degree either the
    shapes or the areas of landmasses.
  • Cartographers use projections to make maps.
  • A map projection is made by transferring points
    and lines on a globes surface onto a sheet of
    paper.
  • Map Projection- any flat map that is a
    representation of a three dimensional object
    three types Mercator, Gnomonic, and Conic

15
Mercator Projection
  • Mercator- a map projection in which both the
    meridians (evenly spaced) and parallels (unevenly
    spaced) are straight and parallel, forming a grid

16
Gnomonic Projection
Gnomonic- parallels appear unevenly spaced,
concentric circles meridians appear as straight
lines radiating from a central point all great
circles appear as straight lines
17
Conic Projections
  • Conic- meridians converge at the poles the
    parallels appear as equally spaced, concentric
    curves
  • Polyconic Projection- several conic projections
    put together to form a larger map

18
Map Reading
  • Legend- the portion of a map that lists all
    symbols and their meanings, distances, and
    intervals aides map reading
  • Map Direction- maps are usually drawn with north
    at the top of the page and south at the bottom
  • Scale- the comparison of the distance on the map
    to the actual distance covered
  • A graphic scale consists of a line that
    represents a certain distance, such as 5 km or 5
    miles.
  • A fractional scale expresses distance as a ratio,
    such as 163 500.

19
Topographic Maps
  • Topographic Map- scientific maps that show
    surface features (such as mountains and valleys)
    by using contour intervals changes 3D into 2D
  • Topographic maps use lines, symbols, and colors
    to represent changes in elevation and features on
    Earths surface.
  • Topography- surface features of the earth
  • Elevation- the height, in feet or meters, above
    or below sea level
  • Mean Sea Level- the point located between the
    highest and lowest tide levels of the ocean

20
Topographic Maps
21
Making Topo Maps
  • Contour Lines-lines on a map that connect points
    of the same elevation
  • Contour Interval- the difference (in feet or
    meters) from one contour line to the next
  • Relief- the change in elevation from the lowest
    to the highest points of an area sometimes
    referred to as vertical relief
  • Index Contours- every fifth contour line on a
    topo map generally bold

22
3D to 2D
23
Depression Contours
  • Depression contour lines are used to represent
    features that are lower than the surrounding
    area.
  • On a map, depression contour lines have
    hachures, or short lines at right angles to the
    contour line that point toward the lower
    elevation, to indicate depressions.

24
Section Assessment
  • Match the following terms with their
    definitions.
  • ___ projection
  • ___ contour interval
  • ___ map legend
  • ___ map scale

A. the difference in elevation between two
side-by-side contour lines B. a diagram that
explains what the symbols on a map
represent C. a map made by transferring points
and lines on a globes surface onto a sheet of
paper D. the ratio between distances on a map and
actual distances on the surface of Earth
C A D B
25
Section Assessment
  • What does it mean if a map says Scale 1100
    000?

This fractional scale means that one unit on the
map represents 100 000 units on Earths surface.
For example, one inch on the map would equal 100
000 inches on Earths surface.
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