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Please turn in Quiz #1

Math review, Mon. & Weds. 4-4:45 pm, in McG-S 230

The Tools of Geography

• maps • GIS• remote

sensing• statistics• numerical

models• LOGIC!

Which object best Which object best approximates the approximates the

shape of the Earth?shape of the Earth?Frisbee Beachball

Not only did the ancient Greeks know the Earth was round, Eratosthenes estimated its diameter within 1% of actual size in 200 BC!

Columbus wasn’t such a rebel after all.

Sun

150

Aswan

Alexandria

7.2°

Circ. = 2 π r

Circumference = 805 km ∙ 50

805 km

Circ. = 40,250 km

r = 6400 km

r = Circ.2π

= 7.2°360°

805 kmCircumference

= 150

7.2°

6378.16 km6378.16 km

6378.16 km6378.16 km6356

.8 k

m63

56.8

km

The 4 Spheres of Geography

Lithosphere

HydrosphereAtmosphere

Biosphere

Lithosphere

HydrosphereAtmosphere

Biosphere

Lithosp

here

Hydro

spher

eAtmosphere

Biosphere

Soil

Systems

An ordered, interrelated set of “things” & their “attributes”

linked by “flows” of energy and/or matter

thing 1thing 1

thing 2thing 2

flowflow

Systems

Systems thinking is vital for all the observational sciences...We can’t run experiments big enough!

Examples of Systems:EcosystemRiver ChannelWeatherPlate Tectonics

Systems

A systems approach to Earth’s energy balance

From: Strahler & Strahler

Where and how does the energy flow in this global-scale natural system?

Open Systems

Matter or energy flows in and out

Input Output

e.g., Crim Dell

Open SystemsSystems can be in

equilibrium (inputs = outputs)

or disequilibrium (inputs ≠ outputs)

Input Output

e.g., Crim Dell

Open SystemsIf Crim Dell is in equilibrium, storage stays

constant: Steady State

What does this mean for the water level through time? It is stable.

Add 500 gallons per week Lose 500 gallons per week

Input Output

e.g., Crim Dell

Open SystemsIf there is a drought and inflow is reduced,

what would you expect to happen?

To outflow?

To storage?

Add 200 gallons per week Lose ??? gallons per week

???

Input Output

e.g., Crim Dell

Open Closed

input output

• inputs and/or outputs of energy or matter in a system

• no inputs or outputs

• matter/energy moves endlessly in series of interconnected paths

= CYCLES

Closed Systems

Closed SystemsWhether a system is open or closed

depends on scale.

Scales range from:

local regional global universal

If we expand the frame of reference to a global scale, most Earth systems become closed; we live on a finite planet

Examples? Exceptions?

Closed Systems

Examples of closed systems:

Rock cycle

Water cycle

Food web*

Carbon cycle* If you include death and decay…

(Lithosphere)

(Hydrosphere)

(Biosphere)

(All four!)

Closed SystemsException:

Solar Inputs Radiation output to space

Energy

Energy as a System

Used by Lord Kelvin to estimate the age of the Earth in 1863 (first extra-Biblical estimate): Given an initial temperature and a present temperature, we know the rate of heat loss, so can calculate an age.

Energy on Earth is not quite in equilibrium

2nd Law of Thermodynamics: Heat flows from warmer bodies (Earth) to cooler bodies (Space)

Led to a huge conflict with Darwin et al.

His age: 20-100 million years; not enough time for evolution or some observed geological phenomena.

Energy as a System

But a scientist’s results are only as good as the data and the assumptions. What did Kelvin not know about?

Convection in the mantle

Heat from the radioactive decay of atomic nuclei