Unit 1 mapping


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Introduction to Mapping

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Unit 1 mapping

  1. 1. Objectives • Compare and contrast latitude and longitude. Latitude and Longitude • Describe how time zones vary. – cartography – equator – latitude – longitude – prime meridian – International Date Line Vocabulary
  2. 2. • Cartographers use an imaginary grid of parallel lines and vertical lines to locate points on Earth. • The equator circles Earth halfway between the north and south poles separating Earth into two equal halves called the northern hemisphere and the southern hemisphere. • Cartography is the science of mapmaking. Latitude and Longitude • For thousands of years, people have used maps to define borders and to find places. Latitude and Longitude
  3. 3. Latitude • Lines of latitude are lines running parallel to the equator. Latitude and Longitude • Latitude is the distance in degrees north or south of the equator.
  4. 4. Latitude • Latitude is thus measured from 0° at the equator to 90° at the poles. Latitude and Longitude • Locations north of the equator are referred to by degrees north latitude (N). • Locations south of the equator are referred to by degrees south latitude (S).
  5. 5. Latitude Degrees of Latitude Latitude and Longitude – Each degree of latitude is equivalent to about 111 km on Earth’s surface. – To locate positions on Earth more precisely, cartographers break down degrees of latitude into 60 smaller units, called minutes (´). – A minute of latitude can be further divided into seconds (´´). – Longitude is also divided into degrees, minutes, and seconds.
  6. 6. Longitude • To locate positions in east and west directions, cartographers use lines of longitude, also known as meridians. Latitude and Longitude • Longitude is the distance in degrees east or west of the prime meridian. • The prime meridian, representing 0° longitude, is the reference point for longitude.
  7. 7. Longitude • Points west of the prime meridian are numbered from 0° to 180° west longitude (W). Latitude and Longitude • Points east of the prime meridian are numbered from 0° to 180° east longitude (E).
  8. 8. Longitude Semicircles Latitude and Longitude – Lines of longitude are not parallel; they are large semicircles that extend vertically from pole to pole. – The distances covered by degrees of longitude vary with location. – One degree of longitude varies from about 111 km at the equator to essentially the distance covered by a point at the poles. Degrees of Longitude
  9. 9. Longitude Locating Places with Coordinates Latitude and Longitude – Both latitude and longitude are needed to precisely locate positions on Earth. – For example, the location of New Orleans is 29°57´N, 90°04´W. – Note that latitude comes first in reference to the coordinates of a particular location.
  10. 10. Time Zones • Because Earth takes about 24 hours to rotate once on its axis, it is divided into 24 times zones, each representing a different hour. Latitude and Longitude
  11. 11. Time Zones • Each time zone is 15° wide, corresponding roughly to lines of longitude. Latitude and Longitude • Time zone boundaries have been adjusted in local areas for convenience.
  12. 12. Time Zones • There are six different time zones in the United States. Latitude and Longitude
  13. 13. Time Zones Calendar Dates Latitude and Longitude – Every time zone experiences this transition from one day to the next, with the calendar advancing to the next day at midnight. – Each time you travel through a time zone, you gain or lose time, eventually gaining or losing an entire day. – The International Date Line, or 180° meridian, serves as the transition line for calendar days. – Traveling west across the International Date Line, you would advance your calendar one day. – Traveling east, you would move your calendar back one day.
  14. 14. Objectives • Compare and contrast different map projections. • Analyze topographic maps. • Describe map characteristics, such as map scales and map legends – Mercator projection – conic projection – gnomonic projection – topographic map – contour line – contour interval – map legend – map scale Vocabulary Types of Maps
  15. 15. Types of Maps • Maps are flat models of a three-dimensional object, Earth. Types of Maps • All flat maps distort to some degree either the shapes or the areas of landmasses. • Cartographers use projections to make maps. • A map projection is made by transferring points and lines on a globe’s surface onto a sheet of paper.
  16. 16. Mercator Projections • A Mercator projection is a map that has parallel lines of latitude and longitude. Types of Maps • In a Mercator projection, the shapes of the landmasses are correct, but their areas are distorted.
  17. 17. Conic Projections • A conic projection is a map made by projecting points and lines from a globe onto a cone. Types of Maps • The cone touches the globe at a particular line of latitude along which there is very little distortion in the areas or shapes of landmasses. • Distortion is evident near the top and bottom of the projection.
  18. 18. Gnomonic Projections • A gnomonic projection is a map made by projecting points and lines from a globe onto a piece of paper that touches the globe at a single point. Types of Maps • Gnomonic projections distort direction and distance between landmasses. • Gnomonic projections are useful in plotting long-distance trips by air or sea.
  19. 19. Gnomonic Projections • Great circles are imaginary lines that divide Earth into two equal halves. Types of Maps • On a sphere such as Earth, the shortest distance between two points lies along a great circle. • Navigators connect points on gnomonic projections to plot great-circle routes.
  20. 20. Topographic Maps • Topographic maps are detailed maps showing the elevations of hills and valleys of an area. Types of Maps • Topographic maps use lines, symbols, and colors to represent changes in elevation and features on Earth’s surface.
  21. 21. Topographic Maps Contour Lines Types of Maps – Elevation on a topographic map is represented by a contour line. – A contour line connects points of equal elevation. – Elevation refers to the distance of a location above or below sea level.
  22. 22. Topographic Maps Contour Intervals Types of Maps – Topographic maps use contour lines to show changes in elevation. – The contour interval is the difference in elevation between two side-by-side contour lines. – The contour interval is dependent on the terrain.
  23. 23. Topographic Maps Index Contours Types of Maps – Index contours are contour lines that are marked by numbers representing their elevations. – If a contour interval on a map is 5 m, you can determine the elevations represented by other lines around the index contour by adding or subtracting 5 m from the elevation indicated on the index contour.
  24. 24. Topographic Maps Depression Contour Lines Types of Maps – Depression contour lines are used to represent features that are lower than the surrounding area. – On a map, depression contour lines have hachures, or short lines at right angles to the contour line that point toward the lower elevation, to indicate depressions.
  25. 25. • These features are represented by different symbols. • A map legend explains what the symbols represent. Map Legends • Topographic maps and most other maps include both human- made and natural features that are located on Earth’s surface. Types of Maps
  26. 26. • A map scale is the ratio between distances on a map and actual distances on the surface of Earth. Map Scales • When using a map, you need to know how to measure distances. Types of Maps
  27. 27. Map Scales • There are three types of map scales: verbal scales, graphic scales, and fractional scales. Types of Maps – A verbal scale expresses distance as a statement, such as “One centimeter is equal to one kilometer.” – A graphic scale consists of a line that represents a certain distance, such as 5 km or 5 miles. – A fractional scale expresses distance as a ratio, such as 1:63 500.
  28. 28. • remote sensing • electromagnetic spectrum • frequency • Landsat satellite Objectives • Compare and contrast the different forms of radiation in the electromagnetic spectrum. • Discuss how satellites and sonar are used to map Earth’s surface and its oceans. • Describe the Global Positioning System. Vocabulary Remote Sensing • Topex/Poseidon satellite • Global Positioning System • sonar
  29. 29. Remote Sensing • Until recently, mapmakers had to go on-site to collect the data needed to make maps. Remote Sensing • Today, advanced technology has changed the way maps are made. • Remote sensing is the process of collecting data about Earth from far above Earth’s surface.
  30. 30. The Electromagnetic Spectrum • Satellites detect different wavelengths of energy reflected or emitted from Earth’s surface. Remote Sensing • This energy has both electric and magnetic properties and is referred to as electromagnetic radiation. • Electromagnetic radiation includes visible light, gamma rays, X rays, ultraviolet waves, infrared waves, radio waves, and microwaves.
  31. 31. The Electromagnetic Spectrum Wave Characteristics Remote Sensing – All electromagnetic waves travel at the speed of 300 000 km/s in a vacuum, a value commonly referred to as the speed of light. – Electromagnetic waves have distinct wavelengths and frequencies. – The electromagnetic spectrum is the arrangement of electromagnetic radiation according to wavelengths. – Frequency is the number of waves that pass a particular point each second. – These unique characteristics help determine how the energy is used by different satellites to map Earth.
  32. 32. The Electromagnetic Spectrum Wave Characteristics Remote Sensing
  33. 33. Landsat Satellites • A Landsat satellite receives reflected wavelengths of energy emitted by Earth’s surface, including some wavelengths of visible light and infrared radiation. Remote Sensing • Since the features on Earth’s surface radiate warmth at slightly different frequencies, they show up as different colors in images
  34. 34. Topex/Poseidon Satellite • The Topex/Poseidon satellite uses radar to accurately map the ocean surface. Remote Sensing • Radar uses high-frequency signals that are transmitted from the satellite to the surface of the ocean. • A receiving device then picks up the returning echo as it is reflected off the water.
  35. 35. Topex/Poseidon Satellite • The distance to the water’s surface is calculated using the known speed of light and the time it takes for the signal to be reflected. Remote Sensing • Variations in time indicate the presence of certain features on the ocean floor as well as many ocean surface features and currents.
  36. 36. The Global Positioning System • The Global Positioning System, or GPS, is a radio-navigation system of at least 24 satellites that allows its users to determine their exact position on Earth. Remote Sensing • Each satellite orbits Earth and transmits high- frequency microwaves that contain information about the satellite’s position and the time of transmission. • A GPS receiver calculates the user’s precise latitude and longitude by processing the signals emitted by multiple satellites.
  37. 37. Sea Beam • Sea Beam technology is similar to the Topex/ Poseidon satellite in that it is used to map the ocean floor. Remote Sensing • Sea Beam is located on a ship and relies on sonar to map ocean-floor features. • Sonar is the use of sound waves to detect and measure objects underwater.
  38. 38. Sea Beam • First, a sound wave is sent from a ship toward the ocean floor. Remote Sensing • A receiving device then picks up the returning echo when it bounces off the seafloor. • Computers on the ship can then calculate the distance to the ocean bottom based on the time it takes the signal to be reflected.