week 2: systems and energy systems science energy: forms and transformations radiation reading:...
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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 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 [email protected]
Earth’s Biosphere
Microbes: most abundant life form. Phytoplankton, bacteria, etc.
Vegetation
????
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?
Posi
tive
Neg
ativ
e
100%
0%
1. Positive2. Negative
But wait, a decrease in the number of bunnies would cause a decrease in the
wolves, so shouldn’t it be a positive coupling?
Yes N
o
83%
17%
1. Yes2. No
Feedbacks
X Y
Something increases X
Positive coupling causes Y to increase when X increases
Positive coupling causes X to increase further when Y increases
+
+
Air T increases, sea surface T increases, causing stronger winds.
Posi
tive
feed
back
loop
Neg
ativ
e fe
edbac
k lo
op
Not a
feed
back
loop
31%
63%
6%
1. Positive feedback loop
2. Negative feedback loop
3. 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 a system’s energy.
2nd Law of Thermodynamics: The equilibrium state of a system has maximum disorder and minimum free energy
Energy “landscape” and equilibrium states.
“Local” equilibrium
unstable equilibrium
“Global” equilibrium
Changes in Climate Time Series
Fluctuations around stationary long-term trend
Fluctuations around non-stationary long-term trend
step change between two mean states
(e.g. Internal readjustments)
(e.g. external forcings or perturbations)
Vostok Ice Core Record
T based on water isotope proxy
E = W + Q
• 1st Law of Thermodynamics
Pred > PATM
PATM
Pred = PATM
PATM
Plunger at rest after expansion
Connection to atmospheric motions
Release plunger
Expansion Work: Happens in Atmosphere
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
system
surroundings
Energy
system
surroundings
Energy
Heat transport through Earth components is a fundamental aspect of climate and weather
For Prof. Thornton’s office hours, I prefer
Tu 1
1:30
Th 1
1:30
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 T
h
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 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
C H
H
H
H + 2O2 CO2 + 2H2O E ~ 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 container and 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 decreases
2. initially increases3. stays constant
How much energy is required to operate a 100-Watt light bulb for 24
hrs (86400 s). 1W = 1J/s
~8.
6x10
6 kJ
~8.
6x10
3 kJ
~24
00 J
52%
8%
41%
1. ~8.6x106 kJ2. ~8.6x103 kJ3. ~2400 J
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?
~ 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 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
Tru
e
Fal
se
52%
48%
1. True2. False
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 constant6.636x10-34 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
220
nm
, 530
nm
, 50.
.
500
0 nm
, 530
nm
, 2..
72%
28%
1. 220 nm, 530 nm, 5000 nm
2. 5000 nm, 530 nm, 220 nm
Electromagnetic SpectrumEnergy increases this way
Wavelength increases this way
The sun emits the most photons as green light (~ 500 nm6x1014 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.
100
0 photo
ns/s
1x1
07 p
hotons
/s
1x1
020
photon
s/s
2%
19%
79%1. 1000 photons/s2. 1x107 photons/s3. 1x1020
photons/s
Electromagnetic SpectrumEnergy increases this way
Wavelength increases this way