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