Contour Mapping

1
Contour Mapping

• Topographic Maps a detailed map showing hills,
  valleys, and other features of a specific area.

2
Vocabulary

• Contour line a line that connects points of
  equal elevation.
• Contour Intervals the difference in elevation
  between contour lines.
• Index Contours contour lines marked by a number
  (elevation)
• Depressions Contours lines that show dips or
  depressions in the land.

3

• Map Legends explains what symbols represent on
  a map.

Example
4
Map Scale the ratio between the distance on the
map and the actual distance on the surface of the
Earth. There are three main types of scales

•  Verbal Scales written in words
• one centimeter equals one kilometer 
•  
• Graphic Scales drawn on a line
•  
•  
• Fractional Scales - written as a fraction
• 162,000 1/62,000

5
Gradient

• The gradient or slope represents how steep the
  land is between two points.
• Gradient change in field value
• distance

6
Topographic Profile

• A topographic profile is a side-view of a
  topographic map along one line. A profile helps
  us see how steep or gentle a slope may be.

7
Remote Sensing

• Most maps have been made by collecting data
  on-site, but recently technology has allowed maps
  to be made from data collected at great
  distances.
• The process of collecting data about the Earth
  from far above the Earths surface is called
  remote sensing.
• Satellites will do most of the remote sensing of
  the Earth.

8
How do satellites collect data?

• The Electromagnetic Spectrum 
• Energy is received and transmitted from the Earth
  through electromagnetic waves (light).
• Different types of waves have different
  properties, such as different wavelengths and
  frequencies.

9
Types of electromagnetic radiation

• Radio waves
• Microwaves
• Infrared radiation
• Visible light
• Ultraviolet radiation
• X-rays
• Gamma rays

10
Wave Characteristics

• All electromagnetic waves travel at 300,000 km/s
  in a vacuum (the speed of light)
•  
• Ø      Wavelength the distance between waves
  (meters)from peak to trough.
•  
•  
• Ø      Frequency the number of waves that pass
  a particular point each second.
•  

11
Landsat Satellites

• Receives reflected wavelengths of energy emitted
  from the Earths surface.
• Features of the Earths surface give off
  different wavelengths of radiation (different
  temperatures)
• Uses a moving mirror to scan the Earth.

12
Topex/Poseidon Satellite

• Maps the ocean floor by measuring the difference
  in high frequency signals that bounce off the
  ocean surface and reach the satellite.
• The ocean water will build-up in shallow areas
  and sink down in deep areas.

13
Sea Beam

• Maps the ocean floor using sound waves (sonar).
• A computer calculates the distance based on how
  fast the sound echo returns to the ship.
• This technology uses the speed of sound in water
  to calculate the distance to the ocean floor.
  (note sounds is faster in water)

14
Global Positioning System (GPS)

• Radio waves from satellites can pinpoint your
  location (latitude longitude), elevation, and
  speed.