GEOGRAPHY 204

PHYSICAL GEOGRAPHY

Spring, 1999

 

LECTURE NOTES

Lecture 3
Lecture 4
Lecture 5
Lecture 6
Lecture 7
Lecture 8
Lecture 9
Lecture 10
Lecture 11
Lecture 12

Lecture 13
Lecture 14
Lecture 15
Lecture 16
Lecture 17
Lecture 18
Lecture 19
Lecture 20
Lecture 21
Lecture 22
Lecture 23

The following lecture notes are unedited. Some topics that are included in the notes may be expanded upon, and some may be left out of the actual lecture completely. Do not use these notes as a substitute for attending lectures and participating in the course-- you'll lose out. I make no promises regarding the completeness of these notes. These notes can be used as a good review, however, or, if you HAVE to miss a lecture, to supplement notes you get from other students in the class.

LECTURE 1 -- INTRODUCTION -- no formal notes.

LECTURE 2 -- January 27

NATURAL SYSTEMS, SPHERES OF EARTH, GEOG GRID

 

Physical Geography -- introduce subfields --

Geomorphology, Climatology, Biogeography, Oceanography, also Hydrology, though this is often in Geology--

all part of Natural Environment

 

Physical Geography focuses on

Natural Environment of the Earth

How environments on earth differ from place to place

SPATIAL DISTRIBUTION

Why environments differ from place to place

PHYSICAL PROCESSES

 Also: interrelationships between different Systems in the Environment --

e.g. How climate affects the land surface, affects the oceans and water on land, affects plants and animals, and how these affect climate

 

Last Time: I mentioned the four spheres

Atmosphere

Hydrosphere

Biosphere

Lithosphere

 None of these can really be separated from the others -- they're all interconnected -- so it's just an artificial division, handy for studying

 

SYSTEMS

 One way of studying these interrelationships is by using the model of a system

 A system is a way of grouping interacting and related events and processes in a particular part of the earth, or, indeed, the entire earth

 EG -- A Watershed -- including all the land where the rain falling on that land ends up in a single stream or stream network --

 So this system includes

the land and soil, plus the

vegetation growing on that land, plus the

animals, birds, snakes, insects, bacteria, etc., plus the

water in the streams and underground, plus

all the air above the land, including all the

weather that happens over that ground, plus the

sunshine that falls on that land

 

All systems have boundaries, arbitrarily assigned, depending on what you want to study

In this case, the boundaries are the drainage divides, at the tops of the hills, where part of the water flows down into the stream that's part of the system, and part flows away into the next stream over

 

Usually systems also have movement of energy and materials in and out of the system

 

This is an example of an OPEN SYSTEM -- because sunshine and rain, and maybe animals pass over the boundaries of the system --

some come into the system

some leave the system

 

One can learn a lot about PROCESSES -- that is, what happens to the land, water, plants, animals, air, sunshine, how they interact, by studying such a system

a CLOSED system is one where no new matter or energy enters or leaves the system --

EG radioactive rock -- theoretically after the rock formed, nothing else entered the rock, no new matter, and nothing within the rock left --

 Except that the radioactive elements in the rock break down through time -- going from high energy to low energy -- so energy is leaving the rock

 

EQUILIBRIUM

 Earth Systems often end up in some sort of Equilibrium --

That is, they tend to come into a balance with incoming and outgoing materials and energy

 For Example the watershed --

If the same amount of water coming in (rain or snow) is balanced by the same amount of water leaving, then the stream stays the same shape and size all the time

 We know that some days it rains a lot, and then it may not rain for days or weeks -- so the incoming water isn't exactly the same all the time

 And sometimes the stream flow is higher and sometimes lower

 But overall, averaging over time, it's the same

This is DYNAMIC EQUILIBRIUM --

Dynamic because it's always changing

Equilibrium because it's in balance, within the changing system

With a Dynamic Equilibrium, there can also be a trend towards change --

gradual change

 Gradually, the water on the hills is carrying particles of rock and soil down into the stream, and the stream carries the rock and soil out of the system -- wearing down gradually through time

 

Sometimes, a Catastrophe comes and changes everything --

a Landslide, or big flood

Then the new system begins to work toward equilibrium again

 

FEEDBACK

 You're all familiar with Feedback, with microphones, or people responding to what you're saying

 In Earth Systems, feedback is a response to a change in the system

 POSITIVE FEEDBACK -- when a change in the system causes increased changes in the system

 Like, with Global Warming

The hotter it gets, the more people use Air Conditioning, which puts more Carbon Dioxide into the Atmosphere, which causes it to get warmer

 NEGATIVE FEEDBACK -- when a change in the system tends to be damped out -- maintaining equilibrium

 Like, the warmer it gets, the more water evaporates into the air, the more clouds form, which block sunshine and cool the earth --

this happens over India during the monsoon rains

 

LOCATIONS ON EARTH'S SURFACE

 GEOGRAPHIC GRID SYSTEM

Star in your notes -- you need to know this

 

People need to be able to locate precise positions on the globe

 Greeks defined a circle as having 360 degrees

 So we divide the globe up into 360 degrees

 We also divide the earth up into HEMISPHERES

 North-South-East-West

 

 Latitude and Longitude

 Imaginary Lines in the Geographic Grid System

 Lines of Latitude -- run around the globe East and West, parallel to the Equator

 Mark locations North and South

 The EQUATOR is Zero Degrees Latitude

 Every line of latitude away from the Equator has a higher number

 North Pole and South Pole -- 90 degrees

 So, person who lives at 45 degrees Latitude lives half way between the Equator and the Pole

 We talk about High Latitude -- near the poles

Low Latitude -- near the Equator

 Latitude is related to how much sunshine a particular location gets, so it's related to climate -- more on that later

 Lines of Latitude are Called Parallels -- Parallel to Equator

 North of the Equator is called the NORTHERN HEMISPHERE

 South of the Equator is called the SOUTHERN HEMISPHERE

 Longitude -- Lines that go from Pole to Pole (Meridians)

 Each Meridian runs from 90 degrees North to 90 degrees south latitude, for a total of 180 degrees -- Half the Earth

 Longitude (Meridians) mark location EAST and WEST

 East and West of WHAT?

 Arbitrary Zero -- Where you begin counting from

 Many countries made maps showing ZERO beginning in the middle of their lands

 By general consensus, it was agreed (by the British Empire, at least) to have the ZERO Longitude run through Greenwich, England, where there is an observatory

 Zero Degrees Longitude is called the PRIME MERIDIAN

 Longitude is measured East and West from the Prime Meridian

 180 degrees East And West -- opposite the Prime Meridian, in the Pacific Ocean

Marks the general location of the INTERNATIONAL DATE LINE

 East of the Prime Meridian to 180 degrees is the EASTERN HEMISPHERE

 West of the Prime Meridian to 180 degrees is the WESTERN HEMISPHERE

 

GREAT CIRCLES

 A Great Circle is an imaginary line that passes through the Center of the Earth -- so it marks the Circumference of the Globe, 360 degrees

 The Equator is the only single Great Circle in the Geog. Grid System

But, TWO OPPOSITE MERIDIANS,

e.g. the Prime Meridian and the 180 degree meridian together

Make a Great Circle -- total 360 degrees

 

DISTANCE ON THE EARTH

 Parallels are spaced evenly from Pole to Pole

As they go away from the Equator, each is covering a smaller and smaller distance around the earth -- Small Circles

However, they're evenly spaced, so

One Degree of Latitude Equals About 111 km (69 miles)

 Meridians converge at the poles --

One degree of Longitude varies from 111 km (69 miles)

at the Equator

to NO distance (a single point) at the Poles

 Go to Lecture 3
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