INTRODUCTION TO PHYSICAL GEOGRAPHY: Chapter 1 The “spheres” of Earth Hydrosphere Lithosphere Atmosphere Biosphere

The earth is elliptical. Which shape type is correct, and why? note: ellipticity exaggerated in photos!

Earth’s dimensions Figure 1.8

Geodesy: Earth Division Latitude: 1 degree = 69 miles 60 minutes = 1 degree (1 minute = 1.15 miles) 1 nautical mile = 1.15 miles 1 second = 1/60 of 1 nautical mile Longitude: lines are not parallel, are called "meridians” -At equator only: 1 degree = 69 miles But declines to zero at the poles

Latitude Figure 1.10

Longitude Figure 1.12

Lines of latitude to know: Equator (O°) starting point to number parallels Tropic of Cancer (23.5° N) Tropic of Capricorn (23.5° S) Arctic Circle (66.5° N) Antarctic Circle (66.5° S)

Important Meridians to know Greenwich or “Prime” (goes through England). Is starting point (0°) for numbering longitude International Date Line: (180° E&W) the place where new days start; is halfway around the world from Greenwich Meridian

Distance on a Globe Question: The shortest distance between two points is: a)a straight line b)A Great Circle Route c)All of the above Answer: c) A Great Circle Route is a circle formed by passing a plane through the exact center of a perfect sphere. Cuts earth into two equal sized pieces.

Great Circles and Small Circles Figure 1.13

MAPS The “perfect map” representation of the earth is a globe True maps are two dimensional: problem of representing a round earth surface on a flat one. The problem with globes is one of scale (example: how large would a globe have to be to include details of Monmouth, Oregon on it?)

Maps and Projections Map – a generalized view of an area, as seen from above and reduced in size Projection – process of transforming the spherical Earth to a flat map

Properties of Maps 1.Scale: ratio of the size of an object (or distance) on the map to the actual size (or distance) of the object that it represents. Examples 1:100 1:10,000 Which shows more detail? 2.Area 3.Shape impossible to preserve area and shape over an entire map

Skip Examples of Map Projections Read Chapter 1; see Appendix A. Ones to be able to recognize: –Mercator (true shape), areas exaggerated at higher latitudes, useful for navigation –Polar

Isoline Mapping uses lines of equal value Examples: 1.Topographic maps: lines of equal elevation 2.Isotherm maps: lines of = temperature 3.Isohyet maps: lines of = precipitation 4.Isobar maps: lines of = pressure

Geographic Information Systems (GIS) GIS is defined as any system which facilitates the analysis of multiple layers of data (maps of specific themes)

GIS System Figure 1.23