Page 74 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

38 Chapter 1 essentials of Geography
5. Sketch a flow diagram of the scientific process and method, beginning with observations and ending with the development of theories and laws.
6. Summarize population-growth issues: population size, the impact per person, and future projections. What strategies do you see as important for global sustainability?
■ Describe systems analysis, open and closed systems, and feedback information, and relate these concepts to Earth systems.
A system is any ordered set of interacting components and their attributes, as distinct from their surrounding environment. Systems analysis is an important organiza- tional and analytical tool used by geographers. Earth is an open system in terms of energy, receiving energy from the Sun, but it is essentially a closed system in terms of matter and physical resources.
As a system operates, “information” is returned to various points in the operational process via pathways of feedback loops. If the feedback information discour- ages change in the system, it is negative feedback. Further production of such feedback opposes system changes. Such negative feedback causes self-regulation in a natural system, stabilizing the system. If feedback information encourages change in the system, it is positive feedback. Further production of positive feed- back stimulates system changes. Unchecked positive feedback in a system can create a runaway (“snowball- ing”) condition. When the rates of inputs and outputs in the system are equal and the amounts of energy and matter in storage within the system are constant (or when they fluctuate around a stable average), the sys- tem is in steady-state equilibrium. A system showing a steady increase or decrease in some operation over time (a trend) is in dynamic equilibrium. A thresh- old, or tipping point, is the moment at which a sys- tem can no longer maintain its character and lurches to a new operational level. Geographers often con- struct a simplified model of natural systems to better understand them.
Four immense open systems powerfully interact at Earth’s surface: three abiotic, or nonliving, systems—the atmosphere, hydrosphere (including the cryosphere), and lithosphere—and a biotic, or living, system—the bio- sphere, or ecosphere.
system (p. 11)
open system (p. 11)
closed system (p. 12)
feedback loop (p. 12)
negative feedback (p. 12) positive feedback (p. 13) steady-state equilibrium (p. 13) dynamic equilibrium (p. 13) threshold (p. 13)
model (p. 14)
abiotic (p. 15)
biotic (p. 15)
atmosphere (p. 15) hydrosphere (p. 15) cryosphere (p. 15)
lithosphere (p. 15)
biosphere (p. 15)
ecosphere (p. 15)
7. Define systems theory as an analytical strategy. What are open systems, closed systems, and nega- tive feedback? When is a system in a steady-state equilibrium condition? What type of system (open or closed) is the human body? A lake? A wheat plant?
8. Describe Earth as a system in terms of both energy and matter; use simple diagrams to illustrate your description.
9. What are the three abiotic spheres that make up Earth’s environment? Relate these to the biotic sphere, the biosphere.
■ Explain Earth’s reference grid: latitude and longitude and latitudinal geographic zones and time.
The science that studies Earth’s shape and size is ge- odesy. Earth bulges slightly through the equator and is oblate (flattened) at the poles, producing a misshapen spheroid, or geoid. Absolute location on Earth is de- scribed with a specific reference grid of parallels of latitude (measuring distances north and south of the equator) and meridians of longitude (measuring dis- tances east and west of a prime meridian). A historic breakthrough in navigation occurred with the establish- ment of an international prime meridian (0° through Greenwich, England). A great circle is any circle of Earth’s circumference whose centre coincides with the centre of Earth. Great circle routes are the shortest dis- tance between two points on Earth. Small circles are those whose centres do not coincide with Earth’s centre.
The prime meridian provided the basis for Greenwich Mean Time (GMT), the world’s first universal time system. Today, Coordinated Universal Time (UTC) is the world- wide standard and the basis for international time zones. A corollary of the prime meridian is the 180° meridian, the International Date Line (IDL), which marks the place where each day officially begins. Daylight saving time is a seasonal change of clocks by 1 hour in summer months.
geodesy (p. 19)
geoid (p. 19)
latitude (p. 20)
parallel (p. 20)
longitude (p. 22)
meridian (p. 22)
prime meridian (p. 22)
great circle (p. 23)
small circle (p. 23)
Greenwich Mean Time (GMT) (p. 24) Coordinated Universal Time (UTC) (p. 25) International Date Line (IDL) (p. 25) daylight saving time (p. 25)
10. Draw a simple sketch describing Earth’s shape and size.
11. Define latitude and parallel and define longitude and meridian using a simple sketch with labels.
12. Define a great circle, great circle routes, and a small circle. In terms of these concepts, describe the equa- tor, other parallels, and meridians.
13. Identify the various latitudinal geographic zones that roughly subdivide Earth’s surface. In which zone do you live?
14. What does timekeeping have to do with longitude? Explain this relationship. How is Coordinated Uni- versal Time (UTC) determined on Earth?