P110/120 Exam 2

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AVG. 81.7 = 71.0%

Climate Change• What is the greenhouse effect?• What are some common green house

gases?• Where is the carbon and how much gets

exchanged per year?• Why do we not have a definitive answer

about how hot we will get?• Behaviour of complex systems (tipping points

etc.)

Absorption by the Atmosphere

http://en.wikipedia.org/wiki/Image:Atmospheric_Transmission.png

http://www.whrc.org/carbon/ (Woods Hole Research Center)

Sediments and sedimentaryRocks could account for another6x107 Petagrams! (www.physicalgeography.net/9r.html)

http://www.whrc.org/carbon/ (Woods Hole Research Center)

H&K Fig. 9.6:

Feedback(positive

and Negative)

“Butterfly effect” in complex systems

COCO22 Concentrations and Temperature Change Concentrations and Temperature Change

Note that total temperature change across several ice ages was only about 12oC or about 22oF.

Next summary will look at this:

Robinson et al. J. Phys. Surg. 12, 79-90 (2007)

These doctors say yes the warming is there, but claim that there is no evidence that the warming is anthropogenic.

Why might you be skeptical of this article?

http://www.mardiros.net/atmosphere/atmosphere_structure.html

10 ppm ozone at ~ 50 km compared to40 ppb ozone in the troposphere!

http://www.atm.ch.cam.ac.uk/tour/part2.html

Ozone levels at Halley Bay station (Antarctica)

TOMS Satellite movie(Total Ozone Mapping Spectrometer)

http://www.atm.ch.cam.ac.uk/tour/anim_toms.html

TOMS Satellite movie(Total Ozone Mapping Spectrometer)

http://www.atm.ch.cam.ac.uk/tour/part2.html

Montreal Protocol (1987-9)

http://en.wikipedia.org/wiki/Montreal_Protocol

Thermal Pollution

• Remember, all energy production eventually leads to thermal energy being dumped into the environment.

• I once had a colleague who claimed this was a strong argument against having unlimited cheap power (as might come from nuclear fusion). How does this compare to the problem of global warming (i.e. to the energy coming from the sun)?

Thermal Pollution: Local water sources

US Electrical power

http://www.eia.doe.gov/fuelelectric.html

Look at the text, whichShows an interestingDistinction betweenUtility producers and Non-utility producersIn terms of this mix.(p 319)

Cooling towers

Basics of electricity• There is a force other than gravity that

acts “at a distance” (and is stronger).• This force can be attractive or repulsive• “Static Electricity” comes in two flavours;

we call these positive and negative (like charges repel, unlike charges attract).

• At least some of the charges in metals are very mobile.

• The force is stronger if charges are closer.• We can define a potential energy

associated with the relative location of charges

Basics of electricity (cont.)• The basics on the previous slide form the basis for

all of our electrical technology!• We measure charge in Coulombs (6.24x1018

elementary charges)• In electrical circuits, you have an “electromotive

force” that provides the “push” (V: VOLTAGE, measured in VOLTS, a potential energy difference per unit charge 1 V = 1J/1 Coulomb)

• Moving charges carry the energy (I: current, measured in AMPS 1 A =1Coul/sec).

• Power = I V (1 watt = 1volt*1 Amp)• The ratio of voltage to current is called the

resistance of the circuit– OHM’s Law: V=IR (R measured in OHMS, )

Batteries

Ohm’s Law

• The ratio of voltage to current in a circuit (or circuit element) is equal to the resistance of that circuit (or element)

R = V / IV = I RI = V/R

• R is measured in OHMS () 1= 1V/1A.

Series and Parallel Circuits

Series circuit: Current is the same in all elements (voltages add)

Parallel circuit: Voltage is the same in all elements (Currents add)

US Electrical Power Generation

North American Power Plants

http://en.wikipedia.org/wiki/Electric_power_transmission

US Electrical power

http://www.eia.doe.gov/cneaf/electricity/epa/epa.pdf#page=15