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). O 3 dissociation. Rad. + conv. Main gases + greenhouse gases (Table 1.1).
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Dx dy =
Atmospheric flow, e.g.,
P ~ po exp(-z/H)
Rad. + conv.
Main gases + greenhouse gases (Table 1.1)
both hemispheres, CCW
Think: right-hand-rule. explains
Flow around a low in NH
Understand (simply) what are the
Major meteorological regimes
And why they are there.
Cryosphere budget (table 2.1)
Earth History:hothouse period, glacial cycles
Exercises: know how to do all of them, will provide
numbers for calc.
Freezing at High Latitude
averaged over surface of earth
CO2 + H2O
Sinks it deeper.
CO2 + H2O -> H2CO3 carbonic acid. Equilibrate w/atmos.
H2CO3 -> H+ + HCO3 bicarbonate ion
HCO3 -> H+ + CO32-
Net: CO2 + CO32- + H2O -> 2HCO3
This is connected to Calcium from the Earth’s mantle:
Ca + 2HCO3 -> CaCO3 + H2CO3coral. 3rd carbon cycle
Where the Ca derived from the weathering of
Rocks containing Ca-Si.
Unique component of Earth’s atmosphere
Increasing with time:
Photosynthesis creates oxygen
- and -
Reduction of water (H2O -> H2 + O) via mineralization,
with hydrogen escaping to space.
~ 4.5 billion years ago (bya): accretion from
planetesimals, evidence is lack of noble gases relative
2. 1st ~750 millions years, named Hadean Epoch: more
bombardment, early atmosphere, moon
3. 1st production of O2, 3.0-3.8 bya.
Low atmos. conc., but ozone layer
4. Increased O2, 2 bya. -> 1st glaciation
Why wasn’t Earth’s surface frozen ?
solar insolation changes
Global sea level ~ 125 m lower
CO2 levels ~ 180 ppm
Snow/ice extent preceeds CO2 changes
Venus Mars Jupiter
Cold & small:
No (liquid) water
No hydrogen or water
Atmosphere all carbon
WHY LIFE ON EARTH ?
ROLE OF OCEANS:
ROLE OF CHEMICAL PHYSICS:
ROLE OF TECTONICS
ROLE OF OTHER PLANETS:
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 = pdry air + pwater vapor; same
For = dry air + water vapor)
p = RdTv where Tv ~ T(1+0.61w) ; w=mvapor/mdry air
hydrostatic eqn., geopotential height and thickness; scale height
Specific heats cv = dq/dT|V constant= du/dT
cp = cv + R
Enthalpy = cpT ; dry static energy =h+
Stays constant if dq=0
Know the “dry” and “moist” variables,
What is conserved when, e,w,q,e,wsat,esat
An air parcel moves over a mountain (3.5.7)
Static stability (z > 0 condition);
Concept behind brunt-vaisala f oscillations;
convective instability (ez > 0 condition);
Entropy dS=dQrev/T => s=cpln
Adiabatic transformations are isentropic
Concept behind Clasius-Clapeyron eqn.
Know the various units
Energy in=energy out
Fsun*pi*R2earth = 4*pi*R2earth*(1.-albedo)*(sigma*T4earth)
global albedo ~ 0.3
=> Tearth = 255 K
Fsun= 1368 W m-2
This + Wien’s law explains why earth’s radiation is in the infrared
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: Fin = Fout 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
Note ozone, surface T
gases,aerosols,clouds,the ocean surface depends on
1. ratio of scatterer size to wavelength:
Size parameter x = 2*pi*scatterer radius/wavelength
Sunlight on a flat ocean
Sunlight on raindrops
IR scattering off of air, aerosol
Microwave scattering off of clouds
proportional to (1/
1 < x < 50
As a first approximation, infrared emissivity and
Cloud albedo can be parameterized as a function of
Liquid water path.
Note dependence on LWP (and optical depth) becomes
unimportant for thick clouds
A further improvement is drop size
r = absorbing gas amount
k =mass extinction coeff.
rk = volume extinction coeff.
Path length ds
Inverse length unit
Cooling to space approximation:
Ignore all intervening layers
Manabe & Strickler, 1965
Rodgers & Walshaw, 1966, QJRMS