Week 2: Systems and Energy
•Systems science
•Energy: forms and transformations
•Radiation
Reading: Chapter 2 of your text
Assignment 2 (Due Friday)
Today –Change in Complex Systems
•Systems
•Earth Climate System
•Couplings and Feedbacks
Earth’s Atmosphere
•Gases and some condensed
phases
•Extends from Earth’s surface to
about 100 Km.
•Primary components % by volume
•N2 (78%)
•O2 (21%)
•Argon (0.9%)
•H2O vapor (0.00001 – 4%)
•CO2 (0.038%)
•Many trace and ultra-trace
components that are important
Earth’s Hydrosphere
Earth’s Lithosphere
Continental Drift: Mechanism for Climate
Change
Movie downloadable from plates@ig.utexas.edu
Earth’s Biosphere
Vegetation
Microbes: most abundant life
form. Phytoplankton, bacteria,
etc.
??
??
Other life forms?
Earth as a Coupled System
Fig 1-1 from text
Couplings
If a change in one
subsystem is “felt” by
another—these parts
are coupled
Couplings can give rise
to feedbacks
An increase in the population of wolves would cause
the population of bunnies to decrease. Is this a
positive or negative coupling?
100%
1. Positive
2. Negative
at
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N
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0%
But wait, a decrease in the number of bunnies
would cause a decrease in the wolves, so shouldn’t
it be a positive coupling?
1. Yes
2. No
83%
o
N
Ye
s
17%
Feedbacks
Positive coupling causes X to
increase further when Y increases
Something
increases X
+
Y
X
+
Positive coupling causes Y to
increase when X increases
Air T increases, sea surface T increases,
causing stronger winds.
1. Positive feedback loop
2. Negative feedback loop
31%
3. Not a feedback loop
63%
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N
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6%
Today –Climate Stability and Energy
•Equilibrium – Stable and Unstable
•Perturbations and Forcings
•Energy: Work + Heat
Today –Announcements
•Please take online poll for office hours!
•Homework 2 link should be working now
•DUE TUESDAY 22nd of JAN
Steady-State and Equilibrium
Steady-state some property does not change in time.
Equilibrium implies steady state, but is more specific to a
system’s energy.
2nd Law of Thermodynamics: The equilibrium state of a
system has maximum disorder and minimum free energy
unstable equilibrium
Energy “landscape” and
equilibrium states.
“Local” equilibrium
“Global” equilibrium
Changes in Climate Time Series
Fluctuations around
stationary longterm trend
(e.g. Internal readjustments)
Fluctuations around
non-stationary
long-term trend
step change between
two mean states
(e.g. external forcings or
perturbations)
Vostok Ice Core Record
T based on water
isotope proxy
E = W + Q
• 1st Law of Thermodynamics
Expansion Work: Happens in Atmosphere
PATM
Release plunger
Pred > PATM
Connection to
atmospheric motions
PATM
Plunger at
rest after
expansion
Pred = PATM
Something Else Involved
Something Else Involved
No mechanical or electrical work done
on the system, and yet, the system’s
ability to do work was increased.
Heat
surroundings
surroundings
Energy
system
Energy
system
Heat transport through Earth components is
a fundamental aspect of climate and weather
For Prof. Thornton’s office hours, I prefer
Tu 11:30
Th 11:30
Tu 4
Th 4
38%
30%
19%
4
Th
4
Tu
:3
0
11
Th
11
:3
0
13%
Tu
1.
2.
3.
4.
For Brian’s 1st office hour set at 9 –
10 AM, I prefer
36%
25%
25%
Th
W
15%
Tu
M
Tu
W
Th
M
1.
2.
3.
4.
For Brian’s 2nd set of office hours, I prefer
53%
5
Th
5
47%
Tu
1. Tu 5
2. Th 5
Today –Announcements
•Please set your preferences for
discussion page.
•Homework link should be working now
•DUE TUESDAY 22nd of JAN
•Brian will take questions about it on
Fri.
Summary
• 1st Law of Thermodynamics
– E = W + Q
• Equilibrium – minimum in energy/order
• Forcings, perturbations, and feedbacks
– Induce natural variability around stable
equilibrium
– or destabilize a system causing a state
change.
Thermochemistry
Heats of Combustion
H
H C H + 2O2  CO2 + 2H2O
H
E ~ 5.6x104 KJ/kg
Heats of Fusion and Vaporization
H2O(s)  H2O(liq) requires 333 KJ/kg of heat
H2O(liq)  H2O(gas) requires 2260 KJ/kg of heat
Consider the amount of heat released when reversed!
I put a glass of water in a dry, insulated container
and record the water temperature which
1. initially decreases
2. initially increases
3. stays constant
67%
19%
t
ta
n
co
ns
ay
s
st
lly
iti
a
in
in
iti
a
lly
de
in
c
cr
e
re
a
as
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se
s
s
14%
How much energy is required to operate a
100-Watt light bulb for 24 hrs (86400 s).
1W = 1J/s
1. ~8.6x106 kJ
2. ~8.6x103 kJ
3. ~2400 J
52%
41%
J
40
0
~2
kJ
3
10
.6
x
~8
~8
.6
x
10
6
kJ
8%
A coal fired power plant can produce 3x107 J per
1 kg of coal burned. How much coal is required to
operate a 100 W light bulb for a day?
1. ~ 3 kg
2. ~ 0.3 kg
3. ~ 300 kg
54%
25%
kg
~
30
0
3
0.
~
~
3
kg
kg
21%
Summary
•Heat flow into or out of a substance changes
its temperature (heat capacity)
•Land-sea T differences
•Energy required to increase sea surface T
•Phase changes require or release heat
•Energy required to melt a glacier
•Energy released during cloud formation
•Evaporative cooling: liquid itself supplies heat
for vaporization
•A form of T regulation
Announcements
• Device ID check
• What’s recorded
• Seminars: www.atmos.washington.edu
– ATMS colloquium Fridays 3:30pm here
– Program on Climate Change
– ESS
Towards a Climate Model
• The energy of a gas is a function of its
temperature only (vice versa).
• Thus, if the atmosphere’s T changes, its
energy balance has changed.
• If we can describe the sources and sinks
of energy, we can predict T.
Earth’s Primary Energy Source
• Light is energy?
• How much energy does the Earth receive?
Charged Particle Motion
-
+
Electromagnetic field disturbance
Charged Particle Motion
-
+
Electromagnetic field disturbance
Charged Particle Motion
+
-
Electromagnetic field disturbance
Charged Particle Motion
-
+
Oscillations in the electric and magnetic fields
move, “radiate”, through space.
Such oscillations are known as electromagnetic
radiation (which encompasses light)
The chair you are sitting on is emitting
electromagnetic radiation
1. True
2. False
52%
ls
e
Fa
Tr
ue
48%
Electromagnetic Radiation
Wavelength (): distance between peaks: m,cm,m
Frequency (): # of full cycles passing a point per second: Hz
 and  related by speed of light (c):  = c/
Energy Carried by Electromagnetic Radiation
The energy a photon carries is directly proportional
to its frequency
Ephoton = h
h is Plank’s constant
6.636x10-34 Js
The intensity (brightness) of radiation is related to the
number of photons of a particular frequency
List the wavelengths of light in order of
increasing energy
1. 220 nm, 530 nm, 5000 nm
2. 5000 nm, 530 nm, 220 nm
72%
..
00
50
22
0
nm
,5
nm
,5
30
30
nm
,5
nm
,2
0.
.
28%
Electromagnetic Spectrum
Energy increases
this way
Wavelength
increases this way
The sun emits the most photons as green light (~ 500
nm6x1014 s-1). Our bodies intercept ~200 W during a
sunny summer day (very rough). Estimate, or guess, roughly
how many green photons your body intercepts per second.
79%
1. 1000 photons/s
2. 1x107 photons/s
3. 1x1020 photons/s
19%
/s
ot
on
s
ph
x1
02
0
ph
7
10
1x
10
00
ph
ot
on
s/
ot
on
s/
s
s
2%
Electromagnetic Spectrum
Energy increases
this way
Wavelength
increases this way