Geosystems

1. Geosystems FIFTHEDITION AN INTRODUCTION TO PHYSICAL GEOGRAPHY Robert W. Christopherson

2. Chapter 1Essentials of Geography Geosystems 5e An Introduction to Physical Geography Robert W. Christopherson Charlie Thomsen

3. Key Learning Concepts After reading the chapter you should be able to: • Define geography and physical geography in particular. • Describe systems analysis, open and closed systems, feedback information, and system operations, and relate these concepts to Earth systems. • Explain Earth’s reference grid: latitude and longitude, and latitudinal geographic zones and time. • Define cartography and mapping basics: map scale and map projections. • Describe remote sensing and explain geographic information system (GIS) methodology as a tool used in methodology as a tool used in geographic analysis.

4. The Science of Geography • Geography – from geo “Earth” and graphein “to write”  • Geography is • A method, not a body of knowledge • Holistic (relating to or concerned with wholes or with complete systems rather than with the analysis of, treatment of, or dissection into parts). • Eclectic (composed of elements drawn from various sources). • Geographers use spatial analysis (the examination of spatial interactions, patterns, and variations over area/or space. Geography is a spatial science; spatial analysis its essential approach). • Spatial- The nature or character of physical space, as in an area; occupying or operating within space.

5. What is the Science of Geography? • Geography is the science that studies the interdependence of geographic areas, places, and locations; natural systems; processes; and societal and cultural activities over Earth's surface. Physical geography involves the spatial analysis of Earth's physical environment. Various words denote the geographic context of spatial analysis: space, territory, zone, pattern, distribution, place, location, region, sphere, province, and distance. Spatial patterns of Earth's weather, climate, winds and ocean currents, topography, and terrestrial biomes are examples of geographic topics.

6. Example of what physical geographers do: • Question: How might a physical geographer analyze water pollution in the Great Lakes? • Answer: Geographers for example can describe the lake elevations, flows, volumes and annual mixing patterns as temperatures change seasonally. They can locate population centers and point sources of pollution using population concentrations estimate non-point sources of pollution. They can map published data of water chemical analyses. They can use a Geographic Information System (GIS) model develop a composite overlay of all the above elements.

7. Geographic themes: • The Association of American Geographers (AAG) and the National Council for Geographic Education (NCGE), set forth five key themes for modern geographic education: location, place, human-Earth relationships, movement, and region.

8. The five geographic themes: • Location: Either absolute or relative location. Location answers the question where? – or the specific planetary address of a location. • Region: Portion of the Earth’s surface with uniform characteristics; how they form and change; how they relate to other regions. • Human-Earth Relationship: Humans and the environment: resource exploitation, hazard perception, and environmental modification- the oldest theme of geographic inquiry. • Place: The characteristics that make each place unique (realistic or spiritual). • Movement: Communication, movement, circulation, and diffusion across Earth’s surface. Global interdependence links all regions and places- both physical and human systems.

9. Geography is also: • The science that studies the relationships among • natural systems, • geographic areas, • society, • cultural activities, • and the interdependence of all of these over space.

10. Content of Geography • Geography derives subject matter from many different sciences. The focus of this class is physical geography but geographers also integrate some human and cultural components. Synthesis of Earth topics and human topics is suggested by movement toward the middle of the continuum- a holistic, or balanced view. (See Figure 1.2- next slide).

11. Figure 1.2

12. Scientific Method • Like all other sciences, geographers use the scientific method approach that uses applied common sense in an organized and objective manner; based on observation, reasoning, hypothesis, predictions, and finally the development of a theory. • Observation: What data are needed? What do we want to know? What questions need answering? • Reasoning: Explanation and interpretation. Building useful models of real systems- conceptual, numerical. • Hypothesis: General statement summarize data, observations, and model simulations. • Predictions: Experiments conducted; more data gathered through observation and measurement; hypothesis refined. • Theory: Real world understood; the knowledge of how things happen and behave as part of broad, general principles.

13. Figure 1: Page 7 Geographers use the scientific method- from perceptions, to observations, reasoning, hypothesis, predictions, and possibly to general theory and natural laws.

14. Earth Systems Concepts • Systems Theory: Geographers use systems methodology as an analytic tool. A system is any ordered, interrelated set of things and their attributes, linked by flows of energy and matter, as distinct from the surrounding environment outside the system.    • Open systems: A system with inputs and outputs crossing back and forth between the system and the surrounding environment. Earth is an open system in terms of energy-why? Other examples are the automobile and a leaf (see next 2 slides). • Closed systems: A system that is shut off from the surrounding environment so that it is entirely self-contained in terms of energy and materials; Earth is a closed system in terms of physical matter and resources.

15. More systems: • System feedback: As a system operates, it generates outputs that influence its own operations. These outputs function as “information” that is returned to various points in the system via pathways called “feedback loops.” Feedback loops can guide further system operations. Example: In plant photosynthesis any increase or decrease in daylight or water can cause a decrease in growth of a plant. • System equilibrium: A system that maintains structure and equilibrium over time. The rates of inputs and outputs in the system are equal and the amounts of energy and matter are constant. Examples: the rotations of planets. Gradual change of the system is defined as Dynamic equilibrium. Examples: Long term climatic changes, increasing temperatures of the atmosphere and oceans.

16. Figure 1.3

17. Open system: Photosynthesis in plants create consumption of light, CO2, nutrients, and H2O and produces oxygen and sugars while at night much of the reverse takes place. Figure 1.4

18. Earth’s Four Spheres • Atmosphere • Hydrosphere • Lithosphere • Biosphere Figure 21.2

19. Earth’s Four Spheres- Plan for the Course. • Atmosphere: (Chap. 2-6). The atmosphere is a thin veil of gases surrounding the Earth, which form a protective boundary between outer space and the biosphere; generally considered to extend about 480 km from the surface. • Hydrosphere: (Chap. 7-10) An abiotic (non biological) open system that includes all of the Earth’s water. • Lithosphere: (Chap. 11-17). Earth’s crust and a portion of the upper mantle directly below the crust form the lithosphere. • Biosphere: (Chap. 18-20). The intricate, interconnected web that links all organisms with their physical environment.

20. Earth’s Dimensions, Location, and Time Calculations   • Dimensions • Latitude • Longitude • Great circles, Small Circles • Prime Meridian and standard time

21. (Figure 1.9) Earth’s dimensions: Earth circumference (a) and diameter (b)- equatorial and polar - are shown. The dashed line is a perfect circle for reference to Earth’s geoid (the surface within or around the earth that is everywhere normal to the direction of gravity and coincides with mean sea level in the oceans). Figure 1.9

22. Latitude • On a map or globe, lines denoting angles of latitude run east and west, parallel to Earth's equator. Latitude is an angular distance north or south of the equator measured from a point at the center of Earth. A line connecting all points along the same latitudinal angle is called a parallel. (See next slide.)

23. Latitude Figure 1.11:

24. Longitude • On a map or globe, lines designating angles of longitude run north and south at right angles (90°) to the equator and all parallels. Longitude is an angular distance east or west of a surface location measured from a point at the center of Earth. A line connecting all points along the same longitude is called a meridian. (See next slide.)

25. Longitude Figure 1.14

26. Great Circles and Small Circles • A great circle is any circle of Earth's cir­cumference whose center coincides with the center of Earth. Every meridian is one-half of a great circle that crosses each parallel at right angles and passes through the poles. An infinite number of great circles can be drawn on Earth, but only one parallel is a great circle–the equatorial parallel. All the rest of the parallels diminish in length toward the poles, and, along with other circles that do not share Earth's center, constitute small circles (See next slide).

27. Great Circles and Small Circles Figure 1.15

28. Prime Meridian and Standard Time • Prime Meridian: the meridian of 0 degrees longitude which runs through the original site of the Royal Observatory at Greenwich, England, and from which other longitudes are measured east or west. Greenwich, England was selected by international agreement in an 1884 treaty. – Greenwich Mean Time (GMT) became the world standard time. (See next slide). • International Date Line: An important corollary of the prime meridian is the 180 degrees meridian on the opposite side of the planet. The meridian is called the International Date Line (IDL) and marks the place where each day officially begins (at 12:01 A.M.). From this “line” the new day sweeps westward. The westward movement is created by the Earth turning eastward on its axis. The IDL deviates from the 180 degrees meridian, this deviation is due to local administrative and political preferences. (See next slide).

29. Figure 1.17: Prime Meridian and Standard Time   Figure 1.17

30. What does timekeeping have to do with longitude? How is Coordinated Universal Time (UTC) determined on Earth? • Earth revolves 360° every 24 hours, or 15° per hour, and a time zone of one hour is estab­lished for each 15° of longitude. Thus, a world standard was established, and time was set with the prime meridian at Greenwich, Eng­land. Each time zone theoretically covers 7.5° on either side of a controlling meridian and represents one hour. Greenwich Mean Time (GMT) is called Coordinated Universal Time (UTC); and although the prime meridian is still at Greenwich, UTC is based on average time calculations kept in Paris and broadcast worldwide. UTC is measured today by the very regular vibrations of cesium atoms in 6 primary standard clocks–the NIST-F1 being the newest placed in operation by the United States in 2000.

31. Maps, Scales, and Projections   • Map – a generalized view of an area, as seen from above and reduced in size • Scale – ratio of map units to ground units • Projection – process of transforming spherical Earth to flat map

32. Maps • A picture -- or a map -- is worth a thousand words! A map is a simplified view of the earth's surface that shows where places and things are located and helps us communicate that information efficiently. In this section, you will learn more about maps and how to read them.

33. Reading Maps • Common Elements: • Maps have certain common elements that help us read them effectively.

35. On a map, the title indicates the geographic area depicted on the map.

36. On a thematic map, the title also indicates the data being presented on the map.

37. Legend • The legend is the key to understanding the map and, together with the title, is the first place you should look when reading a map. The map legend explains the meaning of symbols used on the map.

39. Scale • Scale is a statement of how distance on the map relates to distance on the ground. • Two common expressions of scale are: • Representative fraction • Graphic Bar (or bar scale)

40. Representative fraction   • Example of Representative fraction: • 1:63,360 • Meaning: 1 unit of distance on the map equals 63,360 of the same units on the ground. The ratio is universal: 1cm on the map = 63,360 cm on the ground or 1 inch on the map = 63,360 inches on the ground.

41. Graphic Bar (or bar scale) • Example: Use the graphic scale printed on the map to measure distances on the map in terms of ground distances.

42. Small scale or large scale? • Small scale = less detail (more land coverage), for example 1:1,000,000. • Large scale = more detail (less land coverage), for example 1:10,000. • Sometimes, small scale maps contain "insets" at a larger scale to show detail in a congested area of the small scale map. (See next slide).

43. Example:

44. DIRECTION: Most maps include a "north arrow“ (see below) to reference direction on the map. Maps produced by Statistics Canada usually show "true north", which is the direction to the North Pole of the earth, rather than magnetic north or grid north. The north arrow on a map is usually located in or near the map legend. If a north arrow does not appear on the map, north is assumed to be the top of the map • There are other types of "north" that can be shown on maps. Most topographic maps will show the difference between true, magnetic and grid north. Magnetic north is the north magnetic pole. It is currently located in Nunavut at 78oN 105oW. The north arrow of a magnetic compass points toward the north magnetic pole. (Note: the difference between true north and magnetic north is call ed magnetic declination.) • Grid north is an artificial north that is used on map which have a rectangular grid. The vertical lines do not converge as one proceeds northward. These map are most commonly used for navigation.

45. Features • Thematic maps use symbols to display a specific data theme such as population change, distribution of lone-parent families, average farm income, etc. A minimum amount of reference information, such as boundaries and major water features, help map readers orient themselves to the geographic area covered by the map.

46. Example:

47. Features (continued) • Reference maps use symbols to show the location of physical features, such as roads, railroads, rivers, lakes, etc., and non-visible features such as boundaries, names and codes of geographic areas (See next slide)..

48. Example:

49. Classes of Map Projections • A globe is the only true representation of distance, direction, area, shape, and proximity. A flat map distorts those properties. Therefore, in preparing a flat map, the cartographer must decide which characteristics to preserve, which to distort, and how much distortion is acceptable. Four general classes and perspectives of map projections are used by cartographers: cylindrical, planar, conic, and oval. (See next slide).

50. Classes of Map Projections Figure 1.22