Chapter 2: Mapping Our World

BIG Idea: Earth Scientists use mapping technologies to investigate and describe the world.

I. Latitude and Longitude How can I remember which lines are which? How can I remember which lines are which?

A. Latitude: distance in degrees NORTH and SOUTH of the EQUATOR (0°) Think of latitude like the rungs of a ladder (ladder sounds a lot like latitude). Latitude lines run east and west, but they tell how far up (north) you can go or how far down (south) you can go.

Because lines of latitude never meet, they are also known as… Because lines of latitude never meet, they are also known as…

Parallels: circles around the globe N or S of the Equator Each degree consists of 60 equal parts called minutes. Each degree consists of 60 equal parts called minutes. Each minute is divided into 60 equal parts called seconds. Each minute is divided into 60 equal parts called seconds. D.C. is located at 38°53’51” North

B. distance EAST and WEST of the PRIME MERIDIAN (0°) B. Longitude: distance EAST and WEST of the PRIME MERIDIAN (0°) When you think of longitude, think of long, tall telephone poles (because longitude lines run from pole to pole). Longitude lines run north and south, but they tell how far east you can go or how far west you can go.

Because the Prime MERIDIAN is the main line of longitude, they are also known as… Because the Prime MERIDIAN is the main line of longitude, they are also known as…

Meridians: semicircles running from pole to pole. As with latitude, there are minutes and seconds: As with latitude, there are minutes and seconds: D.C. is 77°0’33” West

Great Circle: any circle that cuts the Earth into a perfect half. any 2 lines of longitude directly across from each other on opposite sides of the globe, or any 2 lines of longitude directly across from each other on opposite sides of the globe, or the Equator (the only parallel of latitude that forms a great circle) the Equator (the only parallel of latitude that forms a great circle)

Using Coordinates Both latitude and longitude are needed to locate positions on Earth precisely. Both latitude and longitude are needed to locate positions on Earth precisely. When giving coordinates, latitude is always given first. When giving coordinates, latitude is always given first. Do you know the coordinates of Staunton, VA? Do you know the coordinates of Staunton, VA?

Latitude: 38° 8' 57" N 38 degrees, 8 minutes, 57 seconds North Latitude: 38° 8' 57" N 38 degrees, 8 minutes, 57 seconds North Longitude: 79° 4' 18" W 79 degrees, 4 minutes, 18 seconds West Longitude: 79° 4' 18" W 79 degrees, 4 minutes, 18 seconds West

Distance The distance on Earth's surface for each one degree of latitude or longitude = 69 miles (111 kilometers) The distance on Earth's surface for each one degree of latitude or longitude = 69 miles (111 kilometers) The distance between lines of latitude remains constant. Why? The distance between lines of latitude remains constant. Why? What happens to the distance between lines of longitude as you move north or south of the Equator? What happens to the distance between lines of longitude as you move north or south of the Equator?

Time Zones Earth is divided into 24 time zones Earth is divided into 24 time zones Why 24? Why 24?

Earth takes about 24 hours to rotate once on its axis (360°) Earth takes about 24 hours to rotate once on its axis (360°) 360° ÷ 24 hours = 15° per hour 360° ÷ 24 hours = 15° per hour Each time zone is 15° wide Each time zone is 15° wide Each time zone represents a different hour Each time zone represents a different hour

International Date Line (IDL) 180° meridian 180° meridian gain or lose a day gain or lose a day travel WEST across the IDL ► advance one calendar day (add 24 hours) travel WEST across the IDL ► advance one calendar day (add 24 hours) travel EAST across the IDL ► move back one calendar day (subtract 24 hours) travel EAST across the IDL ► move back one calendar day (subtract 24 hours)

Why is the IDL crooked?

Wed. Feb. 2, :05:50 Tues. Feb. 1, :05:50

II. Types of Maps Maps are flat projections that come in many different forms Maps are flat projections that come in many different forms

A. Map Projections Map projection: a flat map that represents a 3-dimensional globe Map projection: a flat map that represents a 3-dimensional globe Distortions?

Cartography: the science of map making

1. Mercator Projection: map that is accurate at the equator and highly distorted at the poles.

Mercator projections show correct shapes of landmasses, but the sizes are distorted… Mercator projections show correct shapes of landmasses, but the sizes are distorted… What’s wrong with this picture? What’s wrong with this picture?

2. Conic Projections: cone comes in contact with one parallel of latitude. Polyconic: a series of cones, each on a different parallel Accurate along the parallel the cone is in contact with. * The most accurate projection

3. Gnomonic Projection: most accurate at the poles and shows great circles.

B. Topographic Maps: maps that show topography (surface features and elevation changes)

What are some surface features on Earth that you might find on a topographic map? What are some surface features on Earth that you might find on a topographic map?

mountainsmountains hillshills valleysvalleys riversrivers forestsforests bridgesbridges depressionsdepressions

Contour Lines: lines on a map that connect points of equal elevation.

Contour Interval: the difference in value between adjacent contour lines on a map.

Adjacent: next to next to adjoining adjoining abutting abutting bordering bordering

Contour Rules: 1. Contours never cross or just stop 2. Contours never split 3. The closer they are to each other, the steeper the land 4. The further they are from each other the flatter the land

5. If a contour line shows a “V”, the point of the V points UP hill 6. A river will always flow in the opposite direction of the V’s point (DOWN hill) 7. When contours close in a circle, that represents a hill top

Little ‘teeth’ (hachures) show depressions (holes) in the land

Depression Contour Lines

Topographic Profile The side-view of a surface feature The side-view of a surface feature

Reading a Map list of symbols and their meanings Legend: list of symbols and their meanings ratio between distances on a map and actual distances on Earth’s surface Scale: ratio between distances on a map and actual distances on Earth’s surface one unit on the map equals 25,000 units on Earth’s surface 1:25,000 - one unit on the map equals 25,000 units on Earth’s surface

Finding Direction Geomagnetic poles: points on the Earth’s surface just above the poles of the imaginary magnet Geomagnetic poles: points on the Earth’s surface just above the poles of the imaginary magnet

Magnetic Declination: angle between geographical North Pole and where a compass points to (magnetic north pole). Magnetic Declination: angle between geographical North Pole and where a compass points to (magnetic north pole). True North: Geographic North Pole True North: Geographic North Pole