Transcript Exponential Growth/Decay

P110/120 Exam 2
AVG. 81.7 = 71.0%
12
Frequency
10
8
6
Frequency
4
2
0
45
60
75
Bin
90
110
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
Sediments and sedimentary
Rocks could account for another
6x107 Petagrams!
(www.physicalgeography.net/9r.html)
http://www.whrc.org/carbon/
(Woods Hole Research Center)
http://www.whrc.org/carbon/
(Woods Hole Research Center)
H&K Fig.
9.6:
Feedback
(positive
and
Negative)
“Butterfly effect” in
complex systems
CO2 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:
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?
Robinson et al. J. Phys. Surg. 12, 79-90 (2007)
10 ppm ozone at ~ 50 km compared to
40 ppb ozone in the troposphere!
http://www.mardiros.net/atmosphere/atmosphere_structure.html
Ozone levels at
Halley Bay station
(Antarctica)
http://www.atm.ch.cam.ac.uk/tour/part2.html
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
Look at the text, which
Shows an interesting
Distinction between
Utility producers and
Non-utility producers
In terms of this mix.
(p 319)
http://www.eia.doe.gov/fuelelectric.html
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, W)
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/I
V=IR
I = V/R
• R is measured in OHMS (W) 1W= 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