mapping our world. mapping cartography- cartography- science of map makingscience of map making
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MAPPING OUR WORLD
MAPPING Cartography-
• science of map making
Maps*Flat models of 3-dimensional
spaces
**Earth is always distorted on maps
Typical Graph This is an example of a typical graph we are all
familiar with. The graph is made
up of different “points” with lines that connect the points.
The points are referenced to the x and y axis
Maps are Similar to Graphs
Let each of the four quarters be designated by North or South and East or West.
N
S
EW
What are the 0 points? Equator –
• Separates the Earth into two equal halves called the northern hemisphere and the southern hemisphere
• It is an imaginary belt that runs halfway point between the North Pole and the South Pole.
Equator
What are the O points? Prime Meridian –
• Divides the Earth running North -South• Separates the Earth into two
halves – the Eastern hemisphere and the Western hemisphere
• Goes through Greenwich, England – home of Royal Naval Observatory
P
R
I
M
E
MERIDIAN
East West, North South on the Earth
The N tells us we’re north of the Equator. The S tells us we’re south of the Equator.
The E tells us that we’re east of the Prime Meridian. The W tells us that we’re west of the Prime Meridian.
(N, W) (N, E)
(S, W) (S, E)
Latitude and Longitude The earth is divided into lots of
reference lines called latitude and longitude.
What is Latitude? Latitude is the distance
from the equator along the Y axis.
Lines running parallel to equator
Measures NORTH – SOUTH, but runs East-West
All points along the equator have a value of 0 degrees latitude.
North pole = 90°N South pole = 90°S Values are expressed in
terms of degrees.
Y
X
90°S
90°N
What is Latitude? Each degree of
latitude is divided into 60 minutes.
Each minute is divided into 60 seconds.
Ex: coordinates of Sunny Hills HS
33°52′48″N 117°55′43″W
Y
X
90°S
90°N
This is also true of longitude.
What is Longitude? Longitude is the distance
from the prime meridian along the X axis.
Lines running parallel to Prime Meredian
Measures EAST – WEST, but runs North-South
All points along the prime meridian have avalue of 0 degrees longitude.
The earth is divided into two parts, orhemispheres, of east and west longitude.
Y
X
180°W 180°E
What is Longitude? The earth is divided
into 360 equal slices (meridians)
180 west and 180 east of the prime meridian
Y
X
180°W 180°E
The Size of 1o
Latitude• degree of latitude is approximately 69 miles,
and a minute of latitude is approximately 1.15 miles
Longitude• A degree of longitude varies in size – it
decreases to zero as meridians come together at the poles
• At the equator, it is approximately 69 miles, the same size as a degree of latitude.
• At a latitude of 45 degrees, a degree of longitude is approximately 49 miles.
Coordinate System
Time Zones
The Earth is divided into 24 time zones • Each time zone is 15˚ wide • There are 6 different time zones in the U.S.
Rotation
The Earth rotates 15o of longitude every hour
24 lines of longitude (24 hours) in one day
15 x 24 = 360o total (full circle)• 180o longitude on each side of Prime
Meridian
International Date Line
The International Date Line, or 180˚ meridian, serves as the transition line for calendar days• If you were traveling west across the
IDL, you would advance your calendar one day.
• If you were traveling east across the IDL, you would move your calendar back one day.
See If You Can Tell In Which Quarter These Lon/Lats Are
Located 1. 41°N, 21°E 2. 37°N, 76°W 3. 72°S, 141°W 4. 7°S, 23°W 5. 15°N, 29°E 6. 34°S, 151°E
A B
C D
1. B 2. A3. C4. C5. B6. D
Mercator Projection Parallel lines of latitude and longitude
• Area of land masses near the poles are exaggerated
Used for navigation of planes and ships
Conic Projections Points and lines on a globe are
projected onto a cone-shaped paper. Little distortion in the areas or shapes
of landmasses that fall along this line of latitude• Distortion is evident near top and bottom ofthe projection
• Useful for road maps& weather maps
Gnomonic Projections
Points and lines from a globe are projected onto a paper that touches the globe at a single point. • Distort direction and distance between
landmasses Useful in plotting long-distance trips by air and sea
Topographic Maps
Topographic Map
Show changes in elevation of Earth’s surface
Also show, mountains, rivers, lakes, forests, etc.
Features of Topographic Maps
Relationship between 3D and 2D representation
3D view
2D view
Contour Lines • Contour lines drawn ona map give the elevations for a region.
• Where the lines are close, the slope of the ground is steep.
• Where the lines are farapart, the slope of the ground is gentle.
Contour Lines
Imaginary lines that connects points of equal elevation (height above sea level)
Contour Lines
contour lines do not intersect, branch or cross, except in a vertical or overhanging cliff.
When contour lines cross a stream, they form a “V” with the point of the V pointing upstream
Contour Interval The
difference in elevation between two side-by-side lines
Each map has a unique contour interval, so locate label on the map
Index Contours • Some contour lines
are marked by numbers representing their elevations.
• Practice!
• What is the elevation of the line that is left of the 100m index contour.
Depression Contour Lines
When the elevation is lower than the
surrounding area
there are “hachures” on the line
Contour Map ExampleOn this map, the vertical distance between each of the contour lines
is 10 feet.
1.Which hill is higher, hill A or hill B?
2.Which hill is steeper, hill A or hill B?
3.How many feet of elevation are there between contour lines?
4.How high is hill A? Hill B?
5.Are the contour lines closer on hill A or hill B?
Map Legends
A map legend explains what the symbols on a map represent
A means of showing the relationship between the size of an object indicated on a map and the actual size of the object on the surface of Earth.
DefinitionMap Scales
Fractional scale: - is a fixed ratio between linear measurements on the map and corresponding distances on the ground. Example: 1:62,500
Graphical scale: - is simply a line or bar drawn on the map and divided into units that represent ground distances.
Example:
Verbal scale: - is a convenient way of stating the relationship of map distance to ground distance.
Example: 1 inch equals 1 mile
1 0 1 2 3 4 Miles
Scale Types
Remote Sensing • The Electromagnetic Spectrum
The arrangement of electromagnetic radiation according to wavelengths
• Frequency refers to the # of waves that pass a particular point each second
Wave Characteristics
• Electromagnetic waves travel at the speed of 300,000 km/s in a vacuum“The Speed of Light”
Topex/Poseidon Satellites An emitter sends out-
going signal to the surface of the ocean
A receiver times the returning signal
Distance to ocean’s surface is calculated using the known speed of light and the return time.
Landsat Satellite
Receives reflected wavelengths of energy emitted by Earth’s surface, such as rivers and forests
GPS
A radio-navigation system of at least 24 satellites that allows its users to determine their exact location on Earth.
The receiver calculates the user’s precise lat/long by processing the signals emitted by multiple satellites.
Sea Beam
Used to map the ocean floor
Located on a ship rather than a satellite
Uses sonar which is the use of sound waves to detect and measure objects under water.