Finding Locations on Earth Chapter 3

Latitude  Latitude is the angular distance north or south of the equator.  Run parallel to the equator.  Called parallels because they run east and west around the world.  Measured in degrees.  Degrees North of the equator and Degrees South of the equator.  Can be more precise using minutes and seconds. Example: Washington D.C. = 38°53’51”N.

Longitude  Longitude is the angular distance, measured in degrees, east or west of the prime meridian. (Greenwich, England 0°.)  Meridians are used to establish east and west locations. They run north and south, perpendicular to the equator.  Degrees East of the prime meridian and Degrees West of the prime meridian.  Washington D.C. = 77°0’33”W. It’s exact location is 38°53’51”N, 77°0’33”W.

Finding Direction  Magnetic compass. The compass indicates direction because the Earth has magnetic properties.  Important to find True North when creating a map or for use in navigation. True North can be slightly different due to the location of the geomagnetic north pole versus the geographic north pole.  GPS System

Mapping the Earth’s Surface  Cartography- the science of map making.  Map Projection- a flat map representing the three-dimensional curved surface of a globe.  Three types of map projections: Cylindrical, azimuthal, and conic.

Cylindrical or Mercator  Longitude and latitude are on a grid. It is easy to locate positions using a ruler.  The farther locations are from the equator, the more distorted in size they become.

Azimuthal  Great help in using this type of projection for use in air travel. (Helps in finding the shortest distance between two points.)  Can cause distortion in direction and distance.

Conic  A series of conic projections can be used to create a flat map.

Reading a Map  Maps have symbols for a variety of features.  Symbols are explained in the legend of the map.  Maps are drawn to scale. The scale is the relationship between actual distance and the distance on the map.

Topographic Map  Topographic maps show surface features or topography.  Show natural features such as mountains and rivers, but can also show manmade features such as buildings and roads.

Topographic Map Characteristics:  Elevation: height above sea level.  Contour Lines: lines on the map used to show elevation. -the shape of the contour lines reflects the shape of the land.  Contour Interval: difference in elevation between one contour line and the next.  Relief: difference in elevation between the highest and lowest points being mapped.  Index Contours: every fifth contour line is printed in bold.

Contour Lines that form closed loops indicate a hilltop or a depression. Depression Contours: are marked with short, straight lines.

 Closely spaced contour lines indicate the change in elevation is rapid and that the slope is steep.  Widely spaced contour lines indicate the change in elevation is gradual or the land is flat.  Contour lines that bend and form a “V” indicate a valley.  If a stream flows through a valley, the “V” in the contour lines will point towards the direction from which the water flows.