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Week 2: Systems and Energy
•Systems science
•Energy: forms and transformations
•Radiation
Reading: Chapter 2 of your textAssignment 2 (Due Friday)
Today –Change in Complex Systems
•Systems
•Earth Climate System
•Couplings and Feedbacks
Earth’s Atmosphere•Gases and some condensedphases
•Extends from Earth’s surface toabout 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-tracecomponents that are important
Earth’s Hydrosphere
Earth’s Lithosphere
Continental Drift: Mechanism for ClimateChange
Movie downloadable from [email protected]
Earth’s Biosphere
Microbes: most abundant lifeform. Phytoplankton, bacteria,etc.
Vegetation
????
Other life forms?
Earth as a Coupled System
Fig 1-1 fromtext
Couplings
If a change in onesubsystem is “felt” byanother—these partsare coupled
Couplings can give riseto feedbacks
An increase in the population of wolves would causethe population of bunnies to decrease. Is this a
positive or negative coupling?
Pos
itive
Neg
ativ
e
100%
0%
1. Positive2. Negative
But wait, a decrease in the number of bunnieswould cause a decrease in the wolves, so shouldn’t
it be a positive coupling?
Yes
No
83%
17%
1. Yes2. No
Feedbacks
X Y
Somethingincreases X
Positive coupling causes Y toincrease when X increases
Positive coupling causes X toincrease further when Y increases
+
+
Air T increases, sea surface T increases,causing stronger winds.
Pos
itive
feed
back
loop
Neg
ativ
e fe
edba
ck lo
op
Not
a fe
edba
ck lo
op
31%
63%
6%
1. Positive feedback loop2. Negative feedback loop3. Not a feedback loop
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 EquilibriumSteady-state some property does not change in time.
Equilibrium implies steady state, but is more specific to asystem’s energy.
2nd Law of Thermodynamics: The equilibrium state of asystem has maximum disorder and minimum free energy
Energy “landscape” andequilibrium states.
“Local” equilibrium
unstable equilibrium
“Global” equilibrium
Changes in Climate Time Series
Fluctuations aroundstationary long-term trend
Fluctuations aroundnon-stationarylong-term trend
step change betweentwo mean states
(e.g. Internal readjustments)
(e.g. external forcings orperturbations)
Vostok Ice Core Record
T based on waterisotope proxy
ΔE = ΔW + ΔQ
• 1st Law of Thermodynamics
Pred > PATM
PATM
Pred = PATM
PATM
Plunger atrest afterexpansion
Connection toatmospheric motions
Release plunger
Expansion Work: Happens in Atmosphere
Something Else Involved
Something Else Involved
No mechanical or electrical work doneon the system, and yet, the system’sability to do work was increased.
Heat
system
surroundings
Energysystem
surroundings
Energy
Heat transport through Earth components isa fundamental aspect of climate and weather
For Prof. Thornton’s office hours, I prefer
Tu 1
1:3
0
Th 1
1:3
0
Tu 4
Th 4
38%
13%
30%
19%
1. Tu 11:302. Th 11:303. Tu 44. Th 4
For Brian’s 1st office hour set at 9 –10 AM, I prefer
M Tu
W Th
25% 25%
36%
15%
1. M2. Tu3. W4. Th
For Brian’s 2nd set of office hours, I prefer
Tu 5
Th 5
47%
53%
1. Tu 52. Th 5
Today –Announcements
•Please set your preferences fordiscussion page.
•Homework link should be working now•DUE TUESDAY 22nd of JAN•Brian will take questions about it onFri.
Summary
• 1st Law of Thermodynamics– ΔE = ΔW + ΔQ
• Equilibrium – minimum in energy/order
• Forcings, perturbations, and feedbacks– Induce natural variability around stable
equilibrium– or destabilize a system causing a state
change.
Thermochemistry
C HH
H
H + 2O2 CO2 + 2H2O ΔE ~ 5.6x104 KJ/kg
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!
Heats of Fusion and Vaporization
Heats of Combustion
I put a glass of water in a dry, insulated containerand record the water temperature which
initi
ally
dec
reas
es
initi
ally
incr
ease
s
sta
ys c
onst
ant
14%
67%
19%
1. initially decreases2. initially increases3. stays constant
How much energy is required to operate a100-Watt light bulb for 24 hrs (86400 s).
1W = 1J/s
~8.6
x106 k
J
~8.6
x103 k
J
~2400 J
52%
8%
41%
1. ~8.6x106 kJ2. ~8.6x103 kJ3. ~2400 J
A coal fired power plant can produce 3x107 J per1 kg of coal burned. How much coal is required to
operate a 100 W light bulb for a day?
~ 3
kg
~ 0
.3 k
g
~ 3
00 k
g
21%25%
54%1. ~ 3 kg2. ~ 0.3 kg3. ~ 300 kg
Summary
•Heat flow into or out of a substance changesits 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 heatfor 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 itstemperature only (vice versa).
• Thus, if the atmosphere’s T changes, itsenergy balance has changed.
• If we can describe the sources and sinksof 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 fieldsmove, “radiate”, through space.
Such oscillations are known as electromagneticradiation (which encompasses light)
The chair you are sitting on is emittingelectromagnetic radiation
Tru
e
Fals
e
52%
48%
1. True2. False
Electromagnetic Radiation
Wavelength (λ): distance between peaks: m,cm,µm
Frequency (ν): # of full cycles passing a point per second: Hz
λ and ν related by speed of light (c): ν = c/λ
Energy Carried by Electromagnetic Radiation
The energy a photon carries is directly proportionalto its frequency
Ephoton = hν
h is Plank’s constant6.636x10-34 Js
The intensity (brightness) of radiation is related to thenumber of photons of a particular frequency
List the wavelengths of light in order ofincreasing energy
220
nm
, 530
nm
, 50.
.
500
0 nm
, 530
nm
, 2..
72%
28%
1. 220 nm, 530 nm, 5000 nm2. 5000 nm, 530 nm, 220 nm
Electromagnetic SpectrumEnergy increases this way
Wavelengthincreases this way
The sun emits the most photons as green light (~ 500 nm6x1014 s-1). Our bodies intercept ~200 W during a sunnysummer day (very rough). Estimate, or guess, roughly how
many green photons your body intercepts per second.
100
0 ph
oton
s/s
1x1
07 p
hoto
ns/s
1x1
020
phot
ons/
s
2%
19%
79%
1. 1000 photons/s2. 1x107 photons/s3. 1x1020 photons/s
Electromagnetic SpectrumEnergy increases this way
Wavelengthincreases this way