Finding Locations on EarthFinding Locations on Earth

Chapter 3Chapter 3

LatitudeLatitude

Latitude is the angular distance north or south of Latitude is the angular distance north or south of the equator.the equator.

Run parallel to the equator.Run parallel to the equator. Called Called parallelsparallels because they run east and west because they run east and west

around the world.around the world. Measured in degrees.Measured in degrees. Degrees North of the equator and Degrees Degrees North of the equator and Degrees

South of the equator.South of the equator. Can be more precise using minutes and Can be more precise using minutes and

seconds. Example: Washington D.C. = seconds. Example: Washington D.C. = 3838°53’51”N.°53’51”N.

LongitudeLongitude

Longitude is the angular distance, measured in Longitude is the angular distance, measured in degrees, east or west of the degrees, east or west of the prime meridian.prime meridian. (Greenwich, England 0(Greenwich, England 0°.)°.)

MeridiansMeridians are used to establish east and west are used to establish east and west locations. They run north and south, locations. They run north and south, perpendicular to the equator.perpendicular to the equator.

Degrees East of the prime meridian and Degrees East of the prime meridian and Degrees West of the prime meridian.Degrees West of the prime meridian.

Washington D.C. = 77°0’33”W. It’s exact Washington D.C. = 77°0’33”W. It’s exact location is location is 3838°53’51”N, 77°0’33”W. °53’51”N, 77°0’33”W.

Finding DirectionFinding Direction

Magnetic compass. The compass Magnetic compass. The compass indicates direction because the Earth has indicates direction because the Earth has magnetic properties.magnetic properties.

Important to find Important to find True NorthTrue North when creating when creating a map or for use in navigation. True North a map or for use in navigation. True North can be slightly different due to the location can be slightly different due to the location of the geomagnetic north pole versus the of the geomagnetic north pole versus the geographic north pole.geographic north pole.

Mapping the Earth’s SurfaceMapping the Earth’s Surface

Cartography-Cartography- the science of map making. the science of map making. Map Projection-Map Projection- a flat map representing a flat map representing

the three-dimensional curved surface of a the three-dimensional curved surface of a globe.globe.

Three types of map projections:Three types of map projections:

Mercator, gnomonic, and conic.Mercator, gnomonic, and conic.

MercatorMercator

Longitude and latitude are on a grid. It is Longitude and latitude are on a grid. It is easy to locate positions using a ruler.easy to locate positions using a ruler.

The farther locations are from the equator, The farther locations are from the equator, the more distorted in size they become.the more distorted in size they become.

GnomonicGnomonic

Great help in using this type of projection Great help in using this type of projection for use in air travel. (Helps in finding the for use in air travel. (Helps in finding the shortest distance between two points.)shortest distance between two points.)

Can cause distortion in direction and Can cause distortion in direction and distance.distance.

ConicConic

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

Reading a MapReading a Map

Maps have symbols for a variety of Maps have symbols for a variety of features.features.

Symbols are explained in the Symbols are explained in the legendlegend of the of the map.map.

Maps are drawn to Maps are drawn to scale.scale. The scale is the The scale is the relationship between actual distance and relationship between actual distance and the distance on the map.the distance on the map.

Topographic MapTopographic Map

Topographic maps show surface features Topographic maps show surface features or or topography.topography.

Show natural features such as mountains Show natural features such as mountains and rivers, but can also show manmade and rivers, but can also show manmade features such as buildings and roads.features such as buildings and roads.

Topographic Map Characteristics:Topographic Map Characteristics:

Elevation:Elevation: height above sea level. height above sea level. Contour Lines:Contour Lines: lines on the map used to show lines on the map used to show

elevation.elevation.-the shape of the contour lines reflects the -the shape of the contour lines reflects the shape of the land.shape of the land.

Contour Interval:Contour Interval: difference in elevation between difference in elevation between one contour line and the next.one contour line and the next.

Relief:Relief: difference in elevation between the difference in elevation between the highest and lowest points being mapped.highest and lowest points being mapped.

Index Contours:Index Contours: every fifth contour line is printed every fifth contour line is printed in bold.in bold.

Contour LinesContour Lines that form closed loops indicate a that form closed loops indicate a hilltop or a depression.hilltop or a depression.

Depression Contours:Depression Contours: are marked with short, are marked with short, straight lines.straight lines.

Closely spaced contour lines indicate the Closely spaced contour lines indicate the change in elevation is rapid and that the change in elevation is rapid and that the slope is steep.slope is steep.

Widely spaced contour lines indicate the Widely spaced contour lines indicate the change in elevation is gradual or the land change in elevation is gradual or the land is flat.is flat.

Contour lines that bend and form a “V” Contour lines that bend and form a “V” indicate a valley.indicate a valley.

If a stream flows through a valley, the “V” If a stream flows through a valley, the “V” in the contour lines will point towards the in the contour lines will point towards the direction from which the water flows.direction from which the water flows.