1. Chapter 2: Mapping Our World
Latitude and Longitude
Types of Maps
Remote Sensing

2. 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

3. 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

4. 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

5. 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

6. 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

7. Types of Maps Mercator Projections Conic Projections
Gnomonic Projections
Topographic Maps

8. 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

9. 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

10. 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

11. Gnomonic Projections

12. 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

13. Topographic Maps

14. 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

15. Map Legends
Map legends explain what the symbols on maps represent

16. 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: One centimeter on the map would be equivalent to cm on Earth’s surface

17. 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

18. 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

19. The Electromagnetic Spectrum

20. 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

21. 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

22. 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

23. 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