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Chapter 3. Models of Earth. Finding Locations on Earth: Latitude. A reference grid that is made up of additional circles is used to locate places on Earth‘s surface. Halfway between the poles, a circle called the equator divides Earth into the North and Southern Hemispheres.

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Models of Earth

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Chapter 3

Chapter 3

Models of Earth

Finding locations on earth latitude

Finding Locations on Earth: Latitude

  • A reference grid that is made up of additional circles is used to locate places on Earth‘s surface.

  • Halfway between the poles, a circle called the equator divides Earth into the North and Southern Hemispheres.

  • parallel any circle that runs east and west around Earth and that is parallel to the equator; a line of latitude

  • latitude the angular distance north or south from the equator; expressed in degrees



Models of earth

Degrees of Latitude

  • Latitude is measured in degrees

    • the equator is 0° latitude. T

    • the latitude of both the North Pole and the South Pole is 90°.

  • In actual distance, 1° latitude equals about 111 km.

    Minutes and Seconds

  • Each degree of latitude consists of 60 equal parts, called minutes. One minute (symbol: °) of latitude equals 1.85 km.

  • Each minute is divided into 60 equal parts, called seconds (symbol: °).



  • East-west locations are established by using meridians.

  • meridian any semicircle that runs north and south around Earth from the geographic North Pole to the geographic South Pole; a line of longitude

  • longitude the angular distance east or west from the prime meridian; expressed in degrees



Models of earth

Degrees of Longitude

  • prime meridian - 0° longitude and passes through Greenwich, England

  • International Date Line - The meridian opposite the prime meridian, halfway around the world, is labeled 180°.

    Distance Between Meridians

  • The distance covered by a degree of longitude depends on where the degree is measured. The distance measured by a degree of longitude decreases as you move from the equator toward the poles.

Models of earth


  • The science of making maps is called cartography. Scientists who make maps are called cartographers.

  • Cartographers use data from a variety of sources, such as from field surveys and remote sensing.




Map projections

Map Projections


Reading maps

Reading Maps

  • Many maps also include a compass rose, which is a symbol that indicates the cardinal directions (north, east, south, and west), or an arrow that indicates north.

  • legend a list of map symbols and their meanings

  • scale the relationship between the distance shown on a map and the actual distance

Topographic maps

Topographic Maps

  • One of the most widely used maps is called a topographic map, which shows the surface features of Earth.

  • topography the size and shape of the land surface features of a region

  • elevation the height of an object above sea level

    Advantages of Topographic Maps

  • Topographic maps provide more detailed information about the surface of Earth than either drawings or .

Models of earth

Elevation on Topographic Maps

  • contour line a line that connects points of equal elevation on a map

  • The difference in elevation between one contour line and the next is called the contour interval. The contour interval is selected based on the relief of the area being mapped.

  • relief the difference between the highest and lowest elevations in a given area

  • Every fifth contour line is darker than the four lines one either side of it. This index contour makes reading elevation easier.

Models of earth

  • Closely spaced contour lines indicate that the slope is steep.

  • Widely spaced contour lines indicate that the land is relatively level.

Topographic maps1

Topographic Maps

Practice reading a topographic map

Practice Reading a Topographic Map

  • Refer to page 76 in your textbook.

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