Edhs Maps

Models of the Earth: Using and Interpreting Maps Finding Locations on Earth Mapping the Earth’s Surface Topographic Maps

Thought Question 1. 2. 3.

What is the purpose of maps? How are positions on planet Earth represented/located? Explain how you would go about creating a map by hand. What kinds of tools would you need? What variables would you need to consider?

Objectives 

Distinguish between latitude and longitude  Explain how latitude and longitude can be used to find a location on Earth

Explain how a magnetic compass can be used to find directions on Earth  Describe the characteristics and uses of three types of map projections  Define scale and explain how it can be used to find distance on maps  Explain how elevation and topography can be shown on a map 

 Interpret a topographic map

Why Maps? For thousands of years, people have used maps to define borders and to find places.  Cartography is the science of mapmaking. Cartographers use an imaginary grid of parallel

lines and vertical lines to locate points on Earth.

 The equator circles Earth halfway between the north and south poles separating Earth into two equal halves called the northern hemisphere and the southern hemisphere.

Latitude  Parallels- imaginary circles running

east/west on the globe; determine how far north/south one is; named because they parallel the equator  Latitude- the angular distance from north and south of the Equator; measured in degrees (90° intervals)  Latitudinal Great Circle- Equator is the only latitudinal great circle (any line that separates the earth into two equal parts)

Latitude  

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Latitude is thus measured from 0° at the equator to 90° at the poles.

Locations north of the equator are referred to by degrees north latitude (N). Locations south of the equator are referred to by degrees south latitude (S).

Longitude Meridians- lines running north/south on the globe, pole to pole; determine how far east/west one is  Prime Meridian- the point 0° longitude; runs through Greenwich, England  Longitude- the angular distance east or west of the Prime Meridian; all measured from 0°- 180° east or west of the Prime Meridian 

 Longitudinal Great Circles- any two meridians running directly opposite (180°) from one another; bisect the globe

Longitude Points west of the prime meridian are numbered from 0° to 180° west longitude (W).  Points east of the prime meridian are numbered from 0° to 180° east longitude (E). 

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Locating Places with Coordinates

Both latitude and longitude are needed to precisely locate positions on Earth. For example, the location of New Orleans is: 29°57 ´N, 90°04´W. – Note that latitude comes first in reference to the coordinates of a particular location.

Assessment Match the following terms with their definitions. D latitude ___ B longitude ___ A prime meridian ___ ___ C equator

A. the reference point for longitude B. the distance in degrees east or west of 0° C. the reference point for latitude D. the distance in degrees north or south of 0°

Assessment Identify whether the following statements are true or false. false _______

A degree of longitude always represents the

same distance. true _______ If you travel west across the International Date Line, you advance your calendar one day. false Lines of latitude are not perfectly parallel to _______ each other. true _______ When referencing a specific place on Earth by its coordinates, latitude always comes first.

Direction Finding 

Geomagnetic Poles- the point above the earths poles where all magnetic lines converge;  The earth behaves as a giant magnet with areas near the north and south pole acting as the ends of the magnet; this affects compasses different amounts in different areas

Magnetic Declination- the angle between the direction of the earth’s geographic pole and the direction in which a compass needle points  True North- direction of the geographic north pole 

Thought Question Describe one type of map that you have seen or used. What symbols are used? How are land forms depicted? Name the type of map if you know it. 2) What fields of science use maps and what are the maps used for? 3) Compare and contrast magnetic north and true north. 1)

Mapping The Earth’s Surface  Maps are flat models of a three-

dimensional object, Earth. All flat maps distort to some degree either the

shapes or the areas of landmasses. Cartographers use projections to make maps.

 A map projection is made by transferring points and lines on a globe’s surface onto a sheet of paper. Map Projection- any flat map that is

a representation of a three dimensional object; three types: Mercator, Gnomonic, and Conic

Mercator Projection

Mercator­ a map projection in which both the  meridians (evenly spaced) and parallels (unevenly  spaced) are straight and parallel, forming a grid

Gnomonic Projection Gnomonic­ parallels appear unevenly spaced, concentric  circles; meridians appear as straight lines radiating from a  central point; all great circles appear as straight lines

Conic Projections •Conic­ meridians  converge at the poles;  the parallels appear as  equally spaced,  concentric curves •Polyconic Projection­  several conic  projections put  together to form a  larger map

Map Reading 

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Legend- the portion of a map that lists all symbols and their meanings, distances, and intervals; aides map reading Map Direction- maps are usually drawn with north at the top of the page and south at the bottom Scale- the comparison of the distance on the map to the actual distance covered A graphic scale consists of a line that represents a certain distance, such as 5 km or 5 miles. A fractional scale expresses distance as a ratio, such as 1:63 500.

Topographic Maps 

Topographic Map- scientific maps that show surface features (such as mountains and valleys) by using contour intervals; changes 3D into 2D  Topographic maps use lines, symbols, and colors to represent changes in elevation and features on Earth’s surface.  Topography- surface features of the earth

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Elevation- the height, in feet or meters, above or below sea level  Mean Sea Level- the point located between the highest and lowest tide levels of the ocean

Topographic Maps

Making Topo Maps   

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Contour Lines-lines on a map that connect points of the same elevation Contour Interval- the difference (in feet or meters) from one contour line to the next Relief- the change in elevation from the lowest to the highest points of an area; sometimes referred to as vertical relief Index Contours- every fifth contour line on a topo map; generally bold

3D to 2D

Depression Contours –

Depression contour lines are used to represent features that are lower than the surrounding area. – On a map, depression contour lines have hachures, or short lines at right angles to the contour line that point toward the lower elevation, to indicate depressions.

Section Assessment Match the following terms with their definitions. ___ C projection A contour interval ___ D map legend ___ B map scale ___

A. the difference in elevation between two side-by-side contour lines B. a diagram that explains what the symbols on a map represent C. a map made by transferring points and lines on a globe’s surface onto a sheet of paper D. the ratio between distances on a map and actual distances on the surface of Earth

Section Assessment What does it mean if a map says “Scale 1:100 000”? This fractional scale means that one unit on the map represents 100 000 units on Earth’s surface. For example, one inch on the map would equal 100 000 inches on Earth’s surface.