Maps, Globes, and how to read them:• Maps and globes are drawn to scale.• Scale - relates distance on a map to distance on the earth’s surface.
Scale-Three Types:1. Ratio Scale: For example, one unit on a map could equal 100,000 units on the ground.2. Bar Scale: is a line drawn on a map of known ground length.3. Equivalent Units Scale: states what distance on a map is equal to what distance on the ground
• To locate points on a map or globe, we use the equator, the prime meridian, and longitude and latitude lines.• The units in which points are measured are in degrees (angular distances calculated from the center of the Earth)• To give an exact location, a degree can be broken down into 60 minutes, and a minute broken down into 60 seconds.
• The earth is divided into lines called latitude and longitude.
• Longitude lines run vertically (north and south.)• Latitude lines run horizontally (east and west.) *LATitude is FLAT, LONGgitude is LONG*
• The equator is an imaginary line that runs HALFWAY BETWEEN the North Pole and the South Pole. It is 0 degrees latitude.• The equator divides the earth into a northern and a southern hemisphere. Equator
• The prime meridian is an imaginary line that runs FROM the north pole to the south pole. It is 0 degrees longitude.• The prime meridian divides the earth into eastern and western hemispheres.
•There is a markershowing the actuallocation of the PrimeMeridian inGreenwich, England.
Prime Meridian N • Lat/Long are 2 grid points or coordinates by which you can locate any point onW E earth! Equator • The four quarters of a world map can be designated by S North or South and East or West.
• N tells us we’re north(N, W) (N, E) of the Equator. S tells us we’re south of the Equator. • E tells us that we’re east of the Prime Meridian. W tells us that (S, W) (S, E) we’re west of the Prime Meridian.
• Latitude is90 N Y always measured in degrees North or X South because it is either north or south of the equator. 90 S
Y• Longitude is always measured in degrees East X or West because it is East or West of the prime meridian. 180 W 180 E
(N, W) • That means all points in North America will have a North latitude and a West longitude because it is North of the Equator and West of the Prime Meridian. Prime Meridian
•What would be the latitude and longitude directions in Australia?Prime Meridian Latitude: º South Longitude: º East!
Long or Lat?•Is 30º East a Longitudeor Latitude?Longitude•Is 60º South a Longitudeor Latitude?Latitude
Which Quarter are These Lon/Lats Located In? 0 degrees latitude = equator 1. 41 N, 21 E 1. B 2. 37 N, 76 W 2. A 3. 72 S,141 W 3. CA B 4. 7 S, 23 W 4. C 5. 15 N, 29 EC D 5. B 6. 34 S, 151 E 6. D 0 degrees longitude = prime meridian
• For centuries, maps were drawn by hand.• Mapmakers determined distances and elevation using instruments in a process called surveying.• Now, computers are used to make maps.• Where do computers get the information to make maps?
• Satellites that orbit the earth obtain information which assists with mapping (finding elevation, latitude longitude, and ground covering), measure environmental change, determine urban growth, etc.• The Landsat satellite program began in 1972.• Landsat satellites collect Landsat satellite information which is used to make digital satellite images.
• Landsat satellites record radiation from the surface of the earth in different wavelengths of the electromagnetic spectrum. Much of this radiation we cannot see (ex. infrared).• Computers create images from the radiation and add ―false-color‖ to the wavelengths that we can not normally see. We can learn to identify specific features by the colors of a satellite image.• Grass, trees, crops-red• Water-black or blue• Cities-bluish gray
• GPS (Global Positioning System) is a system of satellites that can be used to make maps.• 3 or 4 satellites are needed to pinpoint the longitude, latitude, and elevation of a location.
• A topographic map is a map showing the surface features of an area.• Who would find topographic maps useful?• Geologists, hikers, park rangers, engineers, government agencies, etc…
• Lines on the map are called contour lines• Contour lines connect points of equal elevation• Mapmakers use contour lines to represent elevation, relief and slope.
• Never cross each other• Connect with themselves• Get closer together as land gets steeper• Get further apart as land gets flatter
•Contour interval- Acontour interval is thedifference in elevationbetween two contourlines that are side byside.•The contour interval isalways the same for thewhole map.•What is the contourinterval for this map?•25 meters.
• An index contour—every 5th contour line— is darker and heavier than the others and is labeled with the elevation in a nice round number.
• To read a topographic map, you must familiarize yourself with the map’s scale, symbols, colors and interpret the map’s contour lines.
• Blue lines/shapes - represent water features, such as streams and lakes.• Brown – contour lines• Black – Roads, buildings, railroads, other man made objects.• Green – Woodland areas• Red - Highways
• Look for areas where the contour lines are close together – they indicate a steep area.• Look for areas where the contour lines are spread apart – they indicate a gentle slope.• Easily visible closed loops indicated a hill top.• Dashed lines indicate a depression (a ―hole‖ in the ground), such as a caldera (collapsed volcano) Steep Slope Gentle Slope
• V-shaped contour lines pointing uphill (to a higher elevation) are valleys.• A stream in a valley flows toward the open end of the V.
Review Questions• How are contour lines drawn on maps? – Connect points of equal elevation, never intersect, form loops although not always visible.• How does a contour map show whether a slope is gentle or steep? – Steep- lines close together – Gentle- lines far apart• V-shaped lines pointing uphill indicate a ___________. Valley• How do you know which way the water is flowing in a valley stream? – Water flows toward open end of the V.