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Geosystems FIFTH EDITION AN INTRODUCTION TO PHYSICAL GEOGRAPHY Robert W. Christopherson
Chapter 1 Essentials of Geography Geosystems 5 e An Introduction to Physical Geography Robert W. Christopherson Charlie Thomsen
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 geographic analysis.
The Science of 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.
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.
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.
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 location place relationships, movement, and region. relationships movement region
The five geographic themes: 1. 2. 3. 4. 5. 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.
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.
Content of 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).
Figure 1. 2
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.
Figure 1: Page 7 Geographers use the scientific method from perceptions, to observations, reasoning, hypothesis, predictions, and possibly to general theory and natural laws.
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.
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.
Figure 1. 3
Open system: Photosynthesis in plants create consumption of light, CO 2, nutrients, and H 2 O and produces oxygen and sugars while at night much of the reverse takes place. Figure 1. 4
Earth’s Four Spheres Atmosphere Hydrosphere Lithosphere Biosphere Figure 21. 2
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.
Earth’s Dimensions, Location, and Time Calculations Dimensions Latitude Longitude Great circles, Small Circles Prime Meridian and standard time
(Figure 1. 9) Earth’s dimensions: Earth circumference (a) and diameter (b)- Earth’s dimensions 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 geoid the direction of gravity and coincides with mean sea level in the oceans). Figure 1. 9
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. )
Figure 1. 11: Latitude
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. )
Longitude Figure 1. 14
Great Circles and Small Circles A great circle is any circle of Earth's cir cumference 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).
Great Circles and Small Circles Figure 1. 15
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 westward by the Earth turning eastward on its axis. The IDL deviates eastward deviates from the 180 degrees meridian, this deviation is due to local administrative and political preferences. (See next slide).
Figure 1. 17: Prime Meridian and Standard Time Figure 1. 17
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 estab lished for each 15° of longitude. Thus, a world standard was established, and time was set with the prime meridian at Greenwich, Eng land. 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-F 1 being the newest placed in operation by the United States in 2000.
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
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.
Reading Maps Common Elements: Maps have certain common elements that help us read them effectively.
On a map, the title indicates the geographic area depicted on the map.
On a thematic map, the title also indicates the data being presented on the map.
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.
Scale is a statement of how distance on the map relates to distance on the ground. Two common expressions of scale are: 1. Representative fraction 2. Graphic Bar (or bar scale)
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: 1 cm on the map = 63, 360 cm on the ground or 1 inch on the map = 63, 360 inches on the ground.
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.
Small scale or large scale? Small scale = less detail (more land coverage), for example 1: 1, 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).
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 78 o. N 105 o. W. 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.
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.
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). .
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).
Classes of Map Projections Figure 1. 22
Modern Earth Measurements: Remote Sensing What is remote sensing? What are you viewing when you observe a weather image on TV? Remote Sensing: Our eyes and cameras are familiar means of obtaining remote sensing information about a distant subject without having physical contact. Remote sensors on satellites and other craft sense a broader range of wavelengths than can our eyes. They can be designed to “see” wavelengths shorter than visible light (ultraviolet) and wavelengths longer than visible light (infrared and microwave radar). Active remote sensing: Active systems direct a beam of energy at a surface and analyze the energy that is reflected back. An example is radar (radio detection and ranging). Passive remote sensing: Passive remote sensing systems record energy radiated from a surface, particularly visible light (like our eyes) and infrared.
Active and Passive Remote Sensing Passive sensing visible light Figure 1. 25 Active sensing radar
Remote Sensing Figure 1. 26
Geographic Information Systems (GIS) GIS systems combine spatial and attribute data Maps can contain multiple data layers: Physical features Cultural features Layers can be added to create composite overlay
Geography and Technology Geography affects us in many ways Our natural environment Our human environment Geography is a Hi Tech discipline Earth Observation Global Positioning Systems (GPS) Geographic Information Systems (GIS)
Earth Observation SPOT Landsat (TM) Radar. SAT NOAA ERS SPOT LANDSAT RADARSAT ERS NOAA
Geographic Information We can describe any Systems element of our world in two ways: Location Information: Where is it? Attribute Information: What is it? Species: Oak Height: 15 m Age: 75 Yrs 51°N, 112°W Describing Our World
GIS - Links Data Sets GIS software links the location data and the attribute data:
GIS - Analysis GIS software can answer questions about our world: Spatial Questions: What provinces border Saskatchewan? Attribute Questions: What provinces have more than 1. 5 million people?
GIS - Layers GIS contains many layers of information: These are just a few of the kinds of layers a GIS can contain: Base Map Data Elevation
GIS - Analysis GIS can analyze data in many ways:
GIS Technology GIS borrows from other software technology: Relational Database Management Systems Computer Assisted Design and Graphics Software Statistical Analysis and Reporting Packages GIS Relational Database CAD Graphics Statistical Analysis
Summary - What is GIS? GIS is about using data to describe our world in two ways: Location Data Where is it? Attribute Data What is it? GIS software maintains a link between layers of location and attribute data With the Link, we can ask questions about our world…
Real World Applications Environmental Park Management Agriculture Public Utilities Health Care Emergency 911 Real Estate Marketing
Park Management Will the new building spoil the Park Scenery? Park planners use Geotechnology to determine if a new Visitor Centre can be seen from the peak.
Agriculture How can I improve food production? Geotechnology is used in making crop management decisions to maximize yields and minimize fertilizer input.
Public Utilities Is it safe to dig here? A proposed excavation, identified by address, is compared to pipelines in the area using Geotechnology.
Health Care What Communities are at risk from Disease? Geotechnology identifies communities at risk of River Blindness and helps determine the impact of treatment.
Emergency 911 What is the fastest route to the Hospital? Geotechnology can choose the fastest route to a hospital. The GIS can take into account traffic and other impediments.
Real Estate Where is my Dream Home? With Geotechnology, an agent can show a map of a neighborhood and a picture or video of the actual properties.
Marketing How can I optimize my Marketing Campaign? Geotechnology can query a database and identify only those areas with the highest household income within a specified distance of a store.
End of Chapter 1 Geosystems 5 e An Introduction to Physical Geography Robert W. Christopherson Charlie Thomsen