Overview of Chapter 1-4: October 17

Chapter 1 Overview

Dx dy =

[R*cos* d][Rd]

Application toAtmospheric flow, e.g.,Exercise 1.20

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O3 dissociation

N2, O2 dissociation

P=mgP ~ po exp(-z/H)

Rad. + conv.

Main gases + greenhouse gases (Table 1.1)

SP NP

Think: right-hand-rule. explainsFlow around a low in NH

Cyclonic: low pressure inboth hemispheres, CCWIn NH

Horizontal heating gradients:aquaplanet simulation

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January

July

Surface winds + SLP, NCEP

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July rainfall

Understand (simply) what are theMajor meteorological regimesAnd why they are there.

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 providenumbers for calc.

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Thermohaline Driver: Heating @ Equator, Cooling andFreezing at High Latitude

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Mass units of 103 kg m-2; equivalent to meters of wateraveraged over surface of earth

CO2 + H2O CH2O +O2

3 Carbon Cycles: The Quickest is

Euphotic zone takes up carbon dioxide, decaying matterSinks it deeper.

2nd CarbonCycle:The Ocean

Carbon in the Oceans:

1. CO2 + H2O -> H2CO3 carbonic acid. Equilibrate w/atmos.2. H2CO3 -> H+ + HCO3 bicarbonate ion3. HCO3 -> H+ + CO3

2-

Net: CO2 + CO32- + H2O -> 2HCO3

This is connected to Calcium from the Earth’s mantle:

Ca + 2HCO3 -> CaCO3 + H2CO3 coral. 3rd carbon cycle

Where the Ca derived from the weathering ofRocks containing Ca-Si.

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Oxygen:

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.

Early Earth’s History, in brief:

1. ~ 4.5 billion years ago (bya): accretion fromplanetesimals, evidence is lack of noble gases relativeto cosmos.

2. 1st ~750 millions years, named Hadean Epoch: morebombardment, 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

Sun’s luminosity increases w/ time as core contracts.

Why wasn’t Earth’s surface frozen ?

Initial high methane conc. gives way to oxygen ->

3 major glaciations. First is ~ 2.3 bya

2nd glaciation: ~ 2.5 million years ago.•Reduced plate tectonics -> reduced volcanic emission of CO2. +•Increased sink of CO2 in oceans through increasedAtmospheric carbon

•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 northernhemisphere summertimesolar insolation changesthat matter

Last glacial maximum 20,000 years ago

Global sea level ~ 125 m lower

CO2 levels ~ 180 ppm

Snow/ice extent preceeds CO2 changes

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Venus Mars JupiterHot: No oceans:No hydrogen or waterAtmosphere all carbon“runaway greenhouseEffect”

Cold & small:No (liquid) waterNo vulcanismNo atmosphere

WHY LIFE ON EARTH ?

ROLE OF OCEANS:ROLE OF CHEMICAL PHYSICS:ROLE OF TECTONICSROLE OF OTHER PLANETS:

Chapter 3: Thermodynamics

Of the W&H questions: ex. 3:18-3.24,3.26-3.36,3.39-3.44, understandIdeas behind 3.53,3.54,3.55.

Nothing on Carnot Cycle. Will probably include a sounding plottedOn 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; sameFor = dry air + water vapor)

p = RdTv where Tv ~ T(1+0.61w) ; w=mvapor/mdry air

Know: hydrostatic eqn., geopotential height and thickness; scale height

1st law of thermo: dq -dw = du

dw=p* dV

Specific heats cv = dq/dT|V constant= du/dTcp = cv + R

Enthalpy = cpT ; dry static energy =h+Stays constant if dq=0

Adiabatic; diabaticKnow the “dry” and “moist” variables,What is conserved when, e,w,q,e,wsat,esat

Td,LCL,latent heating

Understand what happens to these variables asAn air parcel moves over a mountain (3.5.7)

Static stability z > 0 condition) Concept behind brunt-vaisala f oscillations;Conditional instability; convective instability ez > 0 condition);

Entropy dS=dQrev/T => s=cplnAdiabatic transformations are isentropic

Concept behind Clasius-Clapeyron eqn.

Chapter 4: Radiative Transfer

Exercises: 4.11-4.44,4.51,4.55,4.56Know the various units

•Integrated over all wavelengths: E=T4 ;

x 10-8 W m-2 K-4;E is called irradiance, flux density. W/m^2

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Sun Earth

visible

Sahara

Mediterranean

Energy absorbed from Sun establishes Earth’s mean T

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Fsun= 1368 W m-2

@ earth

Energy in=energy outFsun*pi*R2

earth = 4*pi*R2earth*(1.-albedo)*(sigma*T4

earth) global albedo ~ 0.3=> Tearth = 255 K

This + Wien’s law explains why earth’s radiation is in the infrared

High solar transmissivity + low IR transmissivity =Greenhouse effect

Consider multiple isothermal layers, each in radiative equilibrium. Each layer, opaque inthe infrared, emits IR both up and down, while solar is only downTop of atmosphere: Fin = Fout incoming solar flux = outgoing IR fluxAt surface, incoming solar flux + downwelling IR = outgoing IR

=> Outgoing IR at surface, with absorbing atmosphere > outgoing IR with no atmosphere

1.

2.

Manabe&Strickler, 1964:

Note ozone, surface T

Whether/how solar radiation scatters when it impactsgases,aerosols,clouds,the ocean surface depends on

1. ratio of scatterer size to wavelength:

Size parameter x = 2*pi*scatterer radius/wavelength

X large

X small

Sunlight on a flat oceanSunlight on raindrops

IR scattering off of air, aerosolMicrowave scattering off of clouds

Microwave(cm)

Scattering neglected

Rayleigh scattering: solar scattering off of gasesproportional to (1/

aerosol

Cloud drops

R=10-4 m

R=1 m

R=0.1 m

Solar scattering

Gas (air)

Mie scattering:1 < x < 50

Clouds. As a first approximation, infrared emissivity and Cloud albedo can be parameterized as a function ofLiquid water path.

Note dependence on LWP (and optical depth) becomesunimportant for thick clouds

A further improvement is drop size

Radiation transmits through an atmospheric layerAccording to:

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I = intensity= air densityr = absorbing gas amountk =mass extinction coeff.

rk = volume extinction coeff.Inverse length unit

Extinction=scattering+absorption

Path length ds

Radiative heating rate profiles:

Manabe & Strickler, 1965

-or-

Cooling to space approximation:Ignore all intervening layers

Rodgers & Walshaw, 1966, QJRMS