Chapter 2: Mapping Our World - Saluda County School District 1
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Transcript Chapter 2: Mapping Our World - Saluda County School District 1
Chapter 2: Mapping Our
World
Latitude and Longitude
Types of Maps
Remote Sensing
Latitude and Longitude
The science of mapmaking is called cartography
Use an imaginary grid of parallel lines and vertical lines to
locate points on Earth exactly
The grid line halfway between the north and south poles
is called the equator, which separates Earth into two
equal halves called the Northern Hemisphere and the
Southern Hemisphere
Latitude
Lines of latitude run parallel to the equator
Latitude – the distance in degrees north or south of the
equator
The equator = 0°
North Pole = 90° N
South Pole = 90° S
Longitude
Longitude is the distance in degrees east or west of the
prime meridian
The prime meridian represents 0° longitude which goes
through Greenwich, England
Points are numbered 0°-180° West if west of the prime
meridian and 0° - 180° East if east of the prime
meridian
Lines aren’t in parallel to measure longitude, they are in
semicircles from pole to pole
Time Zones
Earth is divided into 24 time zones
Time is always changing because the Earth is ALWAYS
spinning
Each time zone is 15°, roughly corresponding to lines of
longitude
There are 6 different time zones in the United States
Alaska Standard Time, Hawaii-Aleutian Standard Time,
Pacific, Mountain, Central, Eastern
Calendar Dates
Each time you travel through a time zone, you gain/lose
time until, at some point, you gain/lose an entire day
The 180° Prime Meridian is also called the International
Date Line, which serves as the transition line for
calendar days
If you were going west across the line, you would add
one day
If you were going east across the line, you would lose a
day
Types of Maps
Mercator Projections
Conic Projections
Gnomonic Projections
Topographic Maps
Mercator Projections
A map that has parallel
lines of latitude and
longitude
Landmasses at the poles
are exaggerated
Shapes of landmasses are
correct, but their areas are
distorted ex. Greenland and
Australia
Used for plane and ship
navigation
Conic Projections
Made by projecting points
and lines from a globe onto
a cone
Used to make road maps
and weather maps
Highly accurate for small
areas
Distortion near the top and
bottom
Gnomonic Projections
Made by projecting points and lines from a globe onto a
piece of paper that touches the globe at a single point
These projections distort direction and distance
between landmasses
Used in plotting long-distance trips by air and by sea
Great circles – parallels are shown as circles around
the pole
Only show one hemisphere at a time w/ distortion near
the equator
Gnomonic
Projections
Topographic Maps
Topographic maps show changes in elevation of
Earth’s surface
Detailed maps showing the hills and valleys of an area,
also show mountains, rivers, forests, bridges, etc.
Use lines, symbols, colors to represent changes in
elevation and features on Earth’s surface
Topographic Maps
Topographic Maps
Contour Intervals – the space between side-by-side
contour lines that shows difference in elevations
Index Contours – Numbers that represent elevations on
contour lines
Depression Contour Lines – Represent features with
lower elevations than their surroundings, like craters
and mines
Hachures – short lines at right angles to the contour line to
indicate depressions (Figure 2-10 in your book)
point toward lower elevations
Map Legends
Map legends explain
what the symbols on
maps represent
Map Scale
The ratio between distances on a map and actual
distances on the surface of Earth
- Verbal scales – express distance as a statement
- Ex. “one centimeter is equal to one kilometer”
- Graphic scales – consists of a line that represents a
certain distance
- Fractional scales – expresses distance as a ratio
- Ex. 1:63 500 - One centimeter on the map would be
equivalent to 63 500 cm on Earth’s surface
Remote Sensing
Remote sensing is the process of collecting data about
Earth from far above Earth’s surface
Satellites gather information about Earth’s surface
The Electromagnetic
Spectrum
The electromagnetic spectrum is the arrangement of
electromagnetic radiation according to wavelengths
Satellites detect different wavelengths of energy
reflected from Earth’s surface
All electromagnetic waves travel at the speed of light
(300,000 km/s)
Different waves can be described according to
wavelength and/or frequency
Frequency – the number of waves that pass a particular
point each second
The Electromagnetic
Spectrum
Landsat Satellites
Receives reflected wavelengths of energy emitted by
Earth’s surface
Features on Earth’s surface radiate warmth at different
frequencies, so they show up different in images from
satellites
Landsat satellites have a moving mirror with rows of
detectors that measure energy when it scans the
surface of the Earth
Landsat data used to study movements of Earth’s
plates, rivers, earthquakes, pollution
Topex/Poseidon Satellite
Use radar to map features on the ocean floor by using
high-frequency signals transmitted from the satellite to
the ocean surface
The returning echo is reflected off the water
Used to study tidal changes and global ocean currents
Global Positioning System
GPS is a radio-navigation system of many satellites
that allow users to determine their exact position on
Earth
The satellites orbit Earth and transmit microwaves with
info. about the satellites position
Receivers calculate the users precise latitude and
longitude by processing the signals emitted by the
satellites
Sea Beam
Used to map the ocean floor
Located on a ship which uses sonar (sound waves) to
detect and measure objects underwater
Sound waves are sent from the ship to the ocean floor
and an echo is returned after bouncing off the seafloor
Computers calculate the distance to the bottom