Transcript GEOG 123B Lec. #1

FIFTH EDITION
Geosystems
AN INTRODUCTION
TO PHYSICAL GEOGRAPHY
Robert W.
Christopherson
Chapter 1
Essentials of Geography
Geosystems 5e
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
methodology as a tool used in geographic analysis.
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.
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
relationships, movement, and 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
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 1.2next 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 methodfrom 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 selfcontained 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, CO2,
nutrients, and H2O 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)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
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 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).
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
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).
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 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.
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
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: 1cm 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 1:1,000,000.
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).
Example:
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.
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.
Example:
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)..
Example:
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)
RadarSAT
NOAA
ERS
SPOT
LANDSAT
RADARSAT
ERS
NOAA
Geographic Information
Systems
We can describe any
element of our world
in two ways:
Location Information:
Where is it?
Attribute Information:
What is it?
Species: Oak
Height: 15m
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?
GISlayers
- Layers
GIS contains many
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 5e
An Introduction to Physical Geography
Robert W. Christopherson
Charlie Thomsen