Overview of Chapter 1-4: October 17

Chapter 1 Overview
Dx dy =
[R*cos  * d  ][Rd  ]
Application to
Atmospheric flow, e.g.,
Exercise 1.20

N
2
, O
2 dissociation
P=mg
P ~ p o exp(-z/H)
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O
3 dissociation
Rad. + conv.
Main gases + greenhouse gases (Table 1.1)

SP NP
Cyclonic: low pressure in both hemispheres, CCW
In NH
Think: right-hand-rule. explains
Flow around a low in NH

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Surface winds + SLP, NCEP
January
Understand (simply) what are the
Major meteorological regimes
And why they are there.
July
July rainfall
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Chapter 2: The Earth System
Thermohaline circulation
Cryosphere budget (table 2.1)
Carbon Cycle
Oxygen
Earth History:hothouse period, glacial cycles
Exercises: know how to do all of them, will provide numbers for calc.

Thermohaline Driver: Heating @ Equator, Cooling and
Freezing at High Latitude
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Mass units of 10 3 kg m -2 ; equivalent to meters of water averaged over surface of earth

3 Carbon Cycles: The Quickest is
CO
2
+ H
2
O CH
2
O +O
2

Euphotic zone takes up carbon dioxide, decaying matter
Sinks it deeper.
2nd
Carbon
Cycle:
The Ocean

Carbon in the Oceans:
1. CO
2
+ H
2
O -> H
2
CO
3 carbonic acid. Equilibrate w/atmos.
2. H
2
CO
3
-> H + + HCO
3 bicarbonate ion
3.
HCO
3
-> H + + CO
3
2-
Net: CO
2
+ CO
3
2+ H
2
O -> 2HCO
3
This is connected to Calcium from the Earth’s mantle:
Ca + 2HCO
3
-> CaCO
3
+ H
2
CO
3 coral. 3rd carbon cycle
Where the Ca derived from the weathering of
Rocks containing Ca-Si.

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Unique component of Earth’s atmosphere
Increasing with time:
Photosynthesis creates oxygen
- and -
Reduction of water (H
2
O -> H
2
+ O) via mineralization, with hydrogen escaping to space.

Early Earth’s History, in brief:
1. ~ 4.5 billion years ago (bya): accretion from planetesimals, evidence is lack of noble gases relative to cosmos.
2. 1st ~750 millions years, named Hadean Epoch: more bombardment, early atmosphere, moon
3. 1st production of O
2
, 3.0-3.8 bya.
Low atmos. conc., but ozone layer
4. Increased O
2
, 2 bya. -> 1st glaciation

Sun’s luminosity increases w/ time as core contracts.
Why wasn’t Earth’s surface frozen ?

Initial high methane conc. gives way to oxygen ->

2nd glaciation: ~ 2.5 million years ago .
•Reduced plate tectonics -> reduced volcanic emission of CO
2
. +
•Increased sink of CO
2
Atmospheric carbon in oceans through increased
•Movement of Antarctica to SP -> increased albedo
• Drake Passage opens, Panama Isthmus closes
-> Changing thermohaline circulation
-> less poleward heat transport ->colder Arctic
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3rd glaciation mechanism: orbital mechanics primarily northern hemisphere summertime solar insolation changes that matter
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Last glacial maximum 20,000 years ago
Global sea level ~ 125 m lower
CO
2 levels ~ 180 ppm
Snow/ice extent preceeds CO2 changes

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Venus Mars Jupiter
Cold & small:
No (liquid) water Hot:
No oceans:
No hydrogen or water
Atmosphere all carbon
“runaway greenhouse
Effect”
No vulcanism
No atmosphere
WHY LIFE ON EARTH ?
ROLE OF OCEANS:
ROLE OF CHEMICAL PHYSICS:
ROLE OF TECTONICS
ROLE OF OTHER PLANETS:

Chapter 3: Thermodynamics
Of the W&H questions: ex. 3:18-3.24,3.26-3.36,3.39-3.44, understand
Ideas behind 3.53,3.54,3.55.
Nothing on Carnot Cycle. Will probably include a sounding plotted
On a skewT-lnp diagram & ask some questions about it.
Know: gas law p=  RT. Applies separately to dry air, vapor
Connecting to observed p,  where p = p dry air
For  =  dry air
+  water vapor
)
+ p water vapor
; same p =  R d
T v where T v
~ T(1+0.61w) ; w=m vapor
/m dry air
Know: hydrostatic eqn., geopotential height and thickness; scale height

1st law of thermo: dq -dw = du dw=p* dV
Specific heats c v c p
= c v
+ R
= dq/dT|
V constant
= du/dT
Enthalpy = c p
T ; dry static energy =h+ 
Stays constant if dq=0
Adiabatic; diabatic
Know the “dry” and “moist” variables,
What is conserved when,  e,
T d,
LCL,latent heating w,q,e,w sat
,e sat

Understand what happens to these variables as
An air parcel moves over a mountain (3.5.7)
Static stability  z > 0 condition) 
Concept behind brunt-vaisala f oscillations;
Conditional instability; convective instability  e
 z > 0 condition);
Entropy dS=dQ rev
/T => s=c p ln 
Adiabatic transformations are isentropic
Concept behind Clasius-Clapeyron eqn.

Chapter 4: Radiative Transfer
Exercises: 4.11-4.44,4.51,4.55,4.56
Know the various units
•Integrated over all wavelengths: E= 
T 4 ;
 x 10 -8 W m -2 K -4 ;
E is called irradiance, flux density. W/m^2

Sun
Earth
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visible

Sahara
Mediterranean

Energy absorbed from Sun establishes Earth’s mean T
Energy in=energy out
F sun
*pi*R 2 earth
= 4*pi*R 2 earth
*(1.-albedo)*(sigma*T global albedo ~ 0.3
4 earth
)
=> T earth
= 255 K
F sun
= 1368 W m -2
@ earth
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This + Wien’s law explains why earth’s radiation is in the infrared

High solar transmissivity + low IR transmissivity =
Greenhouse effect
1.
2.
Consider multiple isothermal layers, each in radiative equilibrium. Each layer, opaque in the infrared, emits IR both up and down, while solar is only down
Top of atmosphere: F in
= F out incoming solar flux = outgoing IR flux
At surface, incoming solar flux + downwelling IR = outgoing IR
=> Outgoing IR at surface, with absorbing atmosphere > outgoing IR with no atmosphere

Manabe&Strickler, 1964:
Note ozone, surface T

Whether/how solar radiation scatters when it impacts gases,aerosols,clouds,the ocean surface depends on
1. ratio of scatterer size to wavelength:
Size parameter x = 2*pi*scatterer radius/wavelength
X large
Sunlight on a flat ocean
Sunlight on raindrops
Microwave
(cm)
X small
Scattering neglected
IR scattering off of air, aerosol
Microwave scattering off of clouds

Rayleigh scattering: solar scattering off of gases proportional to (1/  
Solar scattering
R=10 -4  m
Gas (air)
R=0.1
 m aerosol
R=1  m
Cloud drops
Mie scattering:
1 < x < 50

As a first approximation, infrared emissivity and
Cloud albedo can be parameterized as a function of
Liquid water path.
A further improvement is drop size
Note dependence on LWP (and optical depth) becomes unimportant for thick clouds

Radiation transmits through an atmospheric layer
According to:
I = intensity
 = air density r = absorbing gas amount k =mass extinction coeff.
Path length ds
 rk = volume extinction coeff.
Inverse length unit
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Extinction=scattering+absorption

Radiative heating rate profiles:
-or-
Cooling to space approximation:
Ignore all intervening layers
Manabe & Strickler, 1965
Rodgers & Walshaw, 1966, QJRMS