Atmospheres & Global Warming Earth and the Other Terrestrial Worlds

Atmospheres Atmospheres &&

Global WarmingGlobal WarmingEarth and the Other Terrestrial WorldsEarth and the Other Terrestrial Worlds

Weather and ClimateWeather and Climate

These are Earth’s These are Earth’s global wind global wind patterns patterns or circulationor circulation• local weather systems move along local weather systems move along

with themwith them

• weather moves from W to E at weather moves from W to E at mid-latitudes in N hemispheremid-latitudes in N hemisphere

Two factors cause these patternsTwo factors cause these patterns• atmospheric heatingatmospheric heating

• planetary rotationplanetary rotation

Weather – short-term changes in wind, clouds, temperature, and pressure in an atmosphere at a given location

Climate – long-term average of the weather at a given location

Global Wind PatternsGlobal Wind Patterns Air heated more at equatorAir heated more at equator

• Warm air rises at equator; Warm air rises at equator; Pressure pushes to polesPressure pushes to poles

• Cold air moves from poles to Cold air moves from poles to equator along the surfaceequator along the surface

Two circulation cells are Two circulation cells are created in each hemisphere created in each hemisphere

Cells of air do not go directly from pole Cells of air do not go directly from pole to equator; air circulation is diverted to equator; air circulation is diverted by…by…

Coriolis effectCoriolis effect• moving objects veer moving objects veer rightright on a surface on a surface

rotating rotating counterclockwisecounterclockwise• moving objects veer moving objects veer leftleft on a surface on a surface

rotating rotating clockwiseclockwise

Global Wind PatternsGlobal Wind Patterns On Earth, the Coriolis effect breaks each On Earth, the Coriolis effect breaks each

circulation cell into three separate cellscirculation cell into three separate cells• winds move either W to E or E to W winds move either W to E or E to W

• Coriolis effect not strong on Mars & Venus• Mars is too small

• Venus rotates too slowly

• In thick Venusian atmosphere, the pole-to-equator circulation cells distribute heat efficiently

• surface temperature is uniform all over the planet

Earth’s AtmosphereEarth’s Atmosphere

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Structure of Earth’s AtmosphereStructure of Earth’s Atmosphere Pressure & density of Pressure & density of decrease decrease with altitudewith altitude Temperature both increases and decreases with altitude Temperature both increases and decreases with altitude

• Temperature domains define the major atmospheric layers Temperature domains define the major atmospheric layers

exosphereexosphere

• low density; fades into spacelow density; fades into space

thermospherethermosphere

• temp begins to rise at the toptemp begins to rise at the top

stratospherestratosphere• UV light heats air (ozone absorbs it.)UV light heats air (ozone absorbs it.)

tropospheretroposphere• layer closest to surfacelayer closest to surface• Convection heats air (rising hot air)Convection heats air (rising hot air)• temp drops with altitudetemp drops with altitude

Ozone Layer (absorbs UV)

(mesosphere)

Troposphere

Stratosphere

Structure of Terrestrial Planet Structure of Terrestrial Planet AtmospheresAtmospheres

Mars, Venus, Earth allMars, Venus, Earth all• have warm tropospheres have warm tropospheres

(and greenhouse gases)(and greenhouse gases)• have warm thermospheres have warm thermospheres

which absorb Solar X rayswhich absorb Solar X rays Only Earth hasOnly Earth has

• a warm stratosphere a warm stratosphere • an UV-absorbing gas (Oan UV-absorbing gas (O33))

All three planets have All three planets have warmer surface temps due warmer surface temps due to greenhouse effectto greenhouse effect

CFCs Attack Ozone (OCFCs Attack Ozone (O33))



The stratospheric ozone is an The stratospheric ozone is an environmental success story. environmental success story. Scientists detected the declining Scientists detected the declining ozone in the atmosphere, ozone in the atmosphere, collecting the evidence that collecting the evidence that convinced governments around convinced governments around the world to take regulatory the world to take regulatory action.action.

Climate History of VenusClimate History of Venus Venus should have outgassed as much HVenus should have outgassed as much H22O as Earth.O as Earth.

• Early on, when the Sun was dimmer, Venus may have had oceans of Early on, when the Sun was dimmer, Venus may have had oceans of waterwater

Venus’ proximity to the Sun caused all HVenus’ proximity to the Sun caused all H22O to evaporate.O to evaporate.

• HH22O caused runaway greenhouse effect O caused runaway greenhouse effect

• surface heated to extreme temperaturesurface heated to extreme temperature

• COCO22 released from rocks: Adds to greenhouse effect released from rocks: Adds to greenhouse effect

• UV photons from Sun dissociate HUV photons from Sun dissociate H22O; HO; H22 escapes, O is stripped escapes, O is stripped

If Earth moved to Venus’ Orbit

Venusian Weather TodayVenusian Weather Today

• Venus has Venus has nono seasons to speak of. seasons to speak of.• rotation axis is nearly 90rotation axis is nearly 90º to the ecliptic planeº to the ecliptic plane

• Venus has little wind at its surfaceVenus has little wind at its surface• rotates very slowly, so there is no Coriolis effectrotates very slowly, so there is no Coriolis effect

• The surface temperature stays constant all over Venus.The surface temperature stays constant all over Venus.• thick atmosphere distributes heat via two large circulation cellsthick atmosphere distributes heat via two large circulation cells

There is no rain on the surface.There is no rain on the surface.• it is too hot and Venus has almost no Hit is too hot and Venus has almost no H22OO

Venusian clouds contain sulfuric acid!Venusian clouds contain sulfuric acid!• implies recent volcanic outgassing?implies recent volcanic outgassing?

Mars’ Thin AtmosphereMars’ Thin Atmosphere

Martian sunset Martian sunset illustrates just how illustrates just how thin the Martian thin the Martian atmosphere is.atmosphere is.



Martian Weather: N Polar Ice Cap & Martian Weather: N Polar Ice Cap & Dust StormDust Storm

Martian Weather TodayMartian Weather Today

• Seasons on Mars are more extreme than on EarthSeasons on Mars are more extreme than on Earth• Mars’ orbit is more ellipticalMars’ orbit is more elliptical

• COCO22 condenses & vaporizes at opposite poles condenses & vaporizes at opposite poles• changes in atmospheric pressure drive pole-to-pole windschanges in atmospheric pressure drive pole-to-pole winds• sometimes cause huge dust stormssometimes cause huge dust storms

The last decade of the The last decade of the 20th Century was the 20th Century was the warmest in the entire warmest in the entire global instrumental global instrumental temperature record, temperature record, starting in the mid-1800’s. starting in the mid-1800’s.

All 10 years rank among the All 10 years rank among the 15 warmest, and include the 15 warmest, and include the 6 warmest years on record. 6 warmest years on record.

Through the reconstruction Through the reconstruction of past climate we can of past climate we can evaluate the rarity and evaluate the rarity and magnitude of this warming.magnitude of this warming.



4.6 Billion Years Ago ...4.6 Billion Years Ago ...

(150 million km from Sun)

1 AU0.7 AU 1.5 AU

SUNSUNVenusVenus EarthEarth MarsMars

Temperature: Top of Atmosphere Temperature: Top of Atmosphere T

emp

erat

ure

(C

elsi

us)

500

300

100

0

-100-100

0

100

200

300

400

500

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

decreases with distance from Sun

1 AU

5500 oC

Earth-18oC (0oF)

Venus

0

-100Distance From Sun

0 AU

Mars

Clue: atm composition

-100

0

100

200

300

400

500

0.5 1 1.5 2

500

300

100

0

-100

Tem

per

atu

re (

Cel

siu

s)

EARTHEARTH:Surface 15oC (60oF)Top of Atm: -18oC (0oF)

All three phases of water

Surface warmer than top of atm Greenhouse Effect

Surface

No Greenhouse

Vibrational Modes for COVibrational Modes for CO22

C OO

CO O

O OC

symmetric

bending 15 m

asymmetric 4.3 m

Greenhouse effect: Radiation at specific wavelengths excite CO2 into higher energy states. Light energy is absorbed by the CO2 molecules

Other Greenhouse GasesOther Greenhouse Gases

O

O O

O

H H

water ozone

N NO C

H

H

H H

methanenitrous oxide

Absorption by different molecules Absorption by different molecules = 0-15 µm = 0-15 µm

Absorption

Transmission

Peak terrestrial emission at ~300K

COCO22

BendingBendingModeMode

How Greenhouse Gases How Greenhouse Gases Warm the TroposphereWarm the Troposphere



CO2

Energy BalanceEnergy Balance

Carbon Dioxide:Carbon Dioxide:in our atmosphere isin our atmosphere is

Increasing rapidlyIncreasing rapidly







Worldwide CO2 EmissionBy fuel type: 1970 - 2020

CO2 Causes Global Warming:Stay tuned . . .



Burning coalBurning coal

gasoline

Natural gas

Since 1850: Since 1850: Atmospheric CO2 has Atmospheric CO2 has increased by 30% increased by 30%

Increase in Temperature tracksIncrease in Greenhouse Gases

Year1850 2000

Temperature vs Time



CO2 in atmosphere, measured in thick arctic ice.

COCO22 Since the Year 1000 AD Since the Year 1000 AD

FAQ 2.1, Figure 1FAQ 2.1, Figure 1

Heat ContentHeat Content::Increase in Atmosphere and Increase in Atmosphere and Ocean since 1945. Ocean since 1945.



CO2

Deuterium (hydrogen with a neutron)

Time (thousands of years before present)

Variations of deuterium (δD) in antarctic ice, which is a proxy for local temperature, and the atmospheric concentrations of the greenhouse gases carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in air trapped within the ice cores and from recent atmospheric measurements. Data cover 650,000 years and the shaded bands indicate current and previous interglacial warm periods.

Figure TS.6Figure TS.6

Patterns of linear global temperature trends over the period 1979 to 2005 estimated at the surface (left), and for the troposphere from satellite records (right). Grey indicates areas with incomplete data. (Bottom) Annual global mean temperatures (black dots) with linear fits to the data. The left hand axis shows temperature anomalies relative to the 1961 to 1990 average and the right hand axis shows estimated actual temperatures, both in °C. Linear trends are shown for the last 25 (yellow), 50 (orange), 100 (magenta) and 150 years (red). The smooth blue curve shows decadal variations (see Appendix 3.A), with the decadal 90% error range shown as a pale blue band about that line. The total temperature increase from the period 1850 to 1899 to the period 2001 to 2005 is 0.76°C ± 0.19°C.

Retreat of GlaciersRetreat of Glaciers



1948 2002

Trift Glacier, Gadmental, Berner, Oberland Switzerland

2006



A 2003 photograph of the ~2.9 square kilometer Easton Glacier on Mount Baker in Washington State. Between ~1890 and 1950, this glacier retreated ~2400 meters. It subsequently expanded 600 meters during a locally cold period between 1950 and 1979. Since then, it has again retreated 315 meters (as of 2002) with 150 meters lost solely between 1997 and 2002.[1]. The extent of the glacier in 1985 is indicated in the figure.

Easton Glacier

http://en.wikipedia.org/wiki/kilometer

http://en.wikipedia.org/wiki/Mount_Baker

http://en.wikipedia.org/wiki/Washington

http://en.wikipedia.org/wiki/glacier

http://en.wikipedia.org/wiki/meter

http://www.globalwarmingart.com/wiki/Image:Easton_Glacier_Terminus_jpg#_note-Pelto

Franz Josef Franz Josef Glacier In RetreatGlacier In Retreat











1951

1960

1964

19391939



All survey regions except Scandinavia show a net thinning. This widespread glacier retreat is generally regarded as a sign of global warming. During this period, 83% of surveyed glaciers showed thinning with an average loss across all glaciers of 0.31 m/yr.

http://en.wikipedia.org/wiki/Scandinavia

http://en.wikipedia.org/wiki/Glacier_retreat

http://en.wikipedia.org/wiki/Global_warming

1500 2000

Receding GlaciersReceding GlaciersGlacierLength (km)

South Cascade Glacier inWashington. The yellow line indicates the location of the terminus in 1958. The red line shows the position of the terminus in 1998.

Is the Sun to Blame ? Is the Sun to Blame ? No. No. Luminosity has been constant.Luminosity has been constant.

Sunlight hitting Earth:

• 11 year Sunspot cycle• Offsets among instruments• No trend



Percentage change in monthly values of the total solar irradiance composites of Willson and Mordvinov (2003; WM2003, violet symbols and line) and Fröhlich and Lean (2004; FL2004, green solid line).

(Solar max)

Global WarmingGlobal Warming Made a political issue by certain people.Made a political issue by certain people.

Three Facts are Absolute:Three Facts are Absolute:

1.1. Earth has warmed by 0.5 C in past 50 years. Temperature rise greatest in Earth has warmed by 0.5 C in past 50 years. Temperature rise greatest in past 10 years.past 10 years.

2.2. Humans are increasing by 30-50% the COHumans are increasing by 30-50% the CO22 in the atmosphere. in the atmosphere.

3.3. Rising CORising CO22 will cause rising temperatures will cause rising temperatures

Only Question: Not Whether, but by how much are humans contributing to Global Warming ?

Feedback Proceses:Feedback Proceses:Positive and Negative Positive and Negative

Suppose Temp rises ==> Suppose Temp rises ==> Evaporation of ocean water.Evaporation of ocean water.

Feedback:Feedback: HH22O is a greenhouse gas ==>O is a greenhouse gas ==>

Earth gets even Warmer !Earth gets even Warmer !

But clouds may form, increasing albedo.But clouds may form, increasing albedo.==> Earth cools.==> Earth cools.

The Arctic:The Arctic:Positive Feedback ProcessPositive Feedback Process

Temp rise causes polar cap ice to melt.Temp rise causes polar cap ice to melt. Artic ground exposed: dirt absorbs more Artic ground exposed: dirt absorbs more

sunlight (lower albedo).sunlight (lower albedo). Ground warms up more: Earth gets hotter.Ground warms up more: Earth gets hotter. More polar cap ice melts. Earth gets even More polar cap ice melts. Earth gets even

hotter.hotter.

Consequences ofConsequences of

Global WarmingGlobal Warming1.1. More evaporation of oceans: More storms, More evaporation of oceans: More storms,

and more severe storms.and more severe storms.2.2. Water in oceans expand with rising Temp. Water in oceans expand with rising Temp.

Sea level has already risen 20 cm in past Sea level has already risen 20 cm in past 100 years. Coastal regions and islands 100 years. Coastal regions and islands flood.flood.

3.3. Polar caps and Glaciers melt: Causes rising Polar caps and Glaciers melt: Causes rising ocean levels.ocean levels.

4.4. Change in ocean current patterns. Change in ocean current patterns. Desserts may get rain; Farmland may get Desserts may get rain; Farmland may get none.none.

Consequences ofConsequences of

Global WarmingGlobal WarmingConsequences of Global WarmingConsequences of Global Warming

According to UN report: the world will be a much hotter place by 2100. +2.4 ｡ : Coral reefs almost extinctIn North America, a new dust-bowl brings deserts to life in the high plains states, centeredd on Nebraska, but also wipes out agriculture andcattle ranching as sand dunes appear across five US states, from Texas in the south to Montana in the north.Rising sea levels accelerate as the Greenland ice sheet tips into irreversible melt, submerging atoll nations and low-lying deltas. In Peru, disappearing Andean glaciers mean 10 million people face water shortages. Warming seas wipe out the Great Barrier Reef and make coral reefs virtually extinct throughout the tropics. Worldwide, a third of all species on the planet face extinction+3.4 ｡ : Rainforest turns to desertThe Amazonian rainforest burns in a firestorm of catastrophic ferocity, covering South America with ash and smoke. Once the smoke clears, the interior of Brazil has become desert, and huge amounts of extra carbon have entered the atmosphere, further boosting global warming. The entire Arctic ice-cap disappears in the summer months, leaving the North Pole ice-free for the first time in 3 million years. Polar bears, walruses and ringed seals all go extinct. Water supplies run short in California as the Sierra Nevada snowpack melts away. Tens of millions are displaced as the Kalahari desert expands across southern Africa+4.4 ｡ : Melting ice caps displace millionsRapidly-rising temperatures in the Arctic put Siberian permafrost in the melt zone, releasing vast quantities of methane and CO2. Global temperatures keep on rising rapidly in consequence. Melting ice-caps and sea level rises displace more than 100 million people, particularly in Bangladesh, the Nile Delta and Shanghai. Heatwaves and drought make much of the sub-tropics uninhabitable: large-scale migration even takes place within Europe, where deserts are growing in southern Spain, Italy and Greece. More than half of wild species are wiped out, in the worst mass extinction since the end of the dinosaurs. Agriculture collapses in Australia+5.4 ｡ : Sea levels rise by five metresThe West Antarctic ice sheet breaks up, eventually adding another five metres to global sea levels. If these temperatures are sustained, the entire planet will become ice-free, and sea

Predictions of temperatures Predictions of temperatures next 100 yearsnext 100 years

DEPENDS ON MAGNITUDE OF FEEDBACK AND RATE OF INCREASE OF GHG. IN 100 YEARS, FORCED CLIMATE CHANGE WILL MOST LIKELY EXCEED NATURAL VARIABILITY



The Kyoto AgreementThe Kyoto Agreement

The Kyoto Protocol, negotiated by more than 160 nations in 1997, will reduce emissions of certain greenhouse gases (primarily CO2). Each of the participating developed countries must decide how to meet its respective reduction goal.

Signed by every country in the Signed by every country in the European Union,European Union,by Japan, and by Russia.by Japan, and by Russia.

Kyoto Agreement:Kyoto Agreement:

The United States Won’t SignThe United States Won’t Sign In March 2001, President Bush announced that the United In March 2001, President Bush announced that the United

States would not sign the Kyoto Protocol on Global Climate States would not sign the Kyoto Protocol on Global Climate Change. Change.

The Protocol requires signatories to cut carbon dioxide The Protocol requires signatories to cut carbon dioxide emissions an average of 5 percent below 1990 levels between emissions an average of 5 percent below 1990 levels between 2008 and 2012. Developing nations are exempt from emission 2008 and 2012. Developing nations are exempt from emission reductions.reductions.

““President Bush strongly opposes any treaty or policy that would President Bush strongly opposes any treaty or policy that would cause the loss of a single American job, let alone the nearly 5 cause the loss of a single American job, let alone the nearly 5 million jobs Kyoto would have cost.” million jobs Kyoto would have cost.” - James Connaughton, chairman of - James Connaughton, chairman of the White House council on Environmental Quality.the White House council on Environmental Quality.

Stop Here.Stop Here.Show: An Inconvenient TruthShow: An Inconvenient Truth

Get DVD somewhere.Get DVD somewhere. Interesting Chapters:Interesting Chapters: 5-9, 11, 16-17, 20, 5-9, 11, 16-17, 20, 21-28, 30-3221-28, 30-32

(or 5-9, 16-28)(or 5-9, 16-28)

Takes 30 min.Takes 30 min.



Three Perspectives onThree Perspectives onGlobal WarmingGlobal Warming

Kyoto Protocol:Kyoto Protocol:

unfccc.int/resource/convkp.htmlunfccc.int/resource/convkp.html

White House Council on Environmental White House Council on Environmental Quality: Quality: www.whitehouse.www.whitehouse.gov/ceqgov/ceq

Pew Center on Global Climate Change:Pew Center on Global Climate Change:

www.pewclimate.orgwww.pewclimate.org

http://www.whitehouse.gov/ceq

http://www.whitehouse.gov/ceq

Clouds, Rain and SnowClouds, Rain and Snow Clouds strongly affect the surface conditions of a planetClouds strongly affect the surface conditions of a planet

• they increase its albedo, thus reflecting away more sunlightthey increase its albedo, thus reflecting away more sunlight• they provide rain and snow, which causes erosionthey provide rain and snow, which causes erosion

Formation of rain and snow:Formation of rain and snow:

Four Major Factors that affectFour Major Factors that affect Long-term Climate Change Long-term Climate Change

Gain/Loss Processes of Atmospheric Gain/Loss Processes of Atmospheric Gas Gas

Unlike the Jovian planets, the terrestrials were too small to Unlike the Jovian planets, the terrestrials were too small to capture significant gas from the Solar nebula.capture significant gas from the Solar nebula.• what gas they did capture was H & He, and it escapedwhat gas they did capture was H & He, and it escaped• present-day atmospheres must have formed at a later timepresent-day atmospheres must have formed at a later time

Sources of atmospheric gas:Sources of atmospheric gas:• outgassingoutgassing – release of gas trapped in interior rock by volcanism – release of gas trapped in interior rock by volcanism• evaporation/sublimationevaporation/sublimation – surface liquids or ices turn to gas when – surface liquids or ices turn to gas when

heatedheated• bombardmentbombardment – micrometeorites, Solar wind particles, or high- – micrometeorites, Solar wind particles, or high-

energy photons blast atoms/molecules out of surface rockenergy photons blast atoms/molecules out of surface rock occurs only if the planet has no substantial atmosphere already occurs only if the planet has no substantial atmosphere already

Gain/Loss Processes of Atmospheric Gain/Loss Processes of Atmospheric GasGas

Ways to lose atmospheric gas:Ways to lose atmospheric gas:• condensationcondensation – gas turns into liquids or ices on the surface when – gas turns into liquids or ices on the surface when

cooledcooled• chemical reactionschemical reactions – gas is bound into surface rocks or liquids – gas is bound into surface rocks or liquids• strippingstripping – gas is knocked out of the upper atmosphere by Solar – gas is knocked out of the upper atmosphere by Solar

wind particleswind particles• impactsimpacts – a comet/asteroid collision with a planet can blast – a comet/asteroid collision with a planet can blast

atmospheric gas into spaceatmospheric gas into space• thermal escapethermal escape – lightweight gas molecules are lost to space when – lightweight gas molecules are lost to space when

they achieve escape velocitythey achieve escape velocity

gas is lost forever!

Origin of the Terrestrial AtmospheresOrigin of the Terrestrial Atmospheres Lack of magnetospheres on Venus & Mars made Lack of magnetospheres on Venus & Mars made

stripping by the Solar wind significant.stripping by the Solar wind significant.• further loss of atmosphere on Marsfurther loss of atmosphere on Mars

• dissociation of Hdissociation of H22O, HO, H22 thermally escapes on Venus thermally escapes on Venus

Gas and liquid/ice exchange occurs through Gas and liquid/ice exchange occurs through condensation and evaporation/sublimation:condensation and evaporation/sublimation:• on Earth with Hon Earth with H22OO

• on Mars with COon Mars with CO22

Since Mercury & the Moon have no substantial Since Mercury & the Moon have no substantial atmosphere, fast particles and high-energy photons atmosphere, fast particles and high-energy photons reach their surfacesreach their surfaces• bombardment creates a rarified exospherebombardment creates a rarified exosphere

Climate History of MarsClimate History of Mars

• More than 3 billion years ago, Mars must have More than 3 billion years ago, Mars must have had a thick COhad a thick CO22 atmosphere and a strong atmosphere and a strong

greenhouse effect.greenhouse effect.• the so-called “warm and wet period”the so-called “warm and wet period”

• Eventually COEventually CO2 2 was lost to space.was lost to space.• some gas was lost to impactssome gas was lost to impacts• cooling interior meant loss of magnetic fieldcooling interior meant loss of magnetic field• Solar wind stripping removed gasSolar wind stripping removed gas

Greenhouse effect weakened until Mars froze. Greenhouse effect weakened until Mars froze.

Rock cycleRock cycle



Water cycleWater cycle



Average amount of time spent in a reservoirAverage amount of time spent in a reservoir

Residence time =Residence time =

amount in reservoir/amount added (removed) per unit amount in reservoir/amount added (removed) per unit timetime

Residence timeResidence time

Amount out/time

Amount in/timeAmount in reservoir

Residence time at BerkeleyResidence time at Berkeley

20,000 students20,000 students 5,000 enter (leave)/year5,000 enter (leave)/year

Residence time?Residence time?

Residence time = 20,000 students/5,000 students/year

= 4 years

Residence time of water in the Residence time of water in the oceanocean

Volume in ocean: 1.3x10Volume in ocean: 1.3x1099 km km33

Discharge from rivers: 3.5x10Discharge from rivers: 3.5x1044 km km33/yr/yr

Residence time: volume/dischargeResidence time: volume/discharge= 1.3x10= 1.3x1099 km km33/ 3.5x10/ 3.5x1044 km km33/yr/yr

= 30 x 10= 30 x 1033 years years

Carbon cycleCarbon cycle



Long term Carbon cycleLong term Carbon cycle



Carbon cycle: volumesCarbon cycle: volumes



MagnetospheresMagnetospheres The Sun ejects a stream of charged particles, called the The Sun ejects a stream of charged particles, called the

solar windsolar wind..• it is mostly electrons, protons, and Helium nucleiit is mostly electrons, protons, and Helium nuclei

Earth’s magnetic field attracts and diverts these charged Earth’s magnetic field attracts and diverts these charged particles to its magnetic poles.particles to its magnetic poles.• the particles spiral along magnetic field lines and emit lightthe particles spiral along magnetic field lines and emit light• this causes the this causes the auroraaurora (aka northern & southern lights) (aka northern & southern lights)• this protective “bubble” is called the this protective “bubble” is called the magnetospheremagnetosphere

Other terrestrial worlds have Other terrestrial worlds have nono strong magnetic fields strong magnetic fields• solar wind particles impact the exospheres of Venus & Marssolar wind particles impact the exospheres of Venus & Mars• solar wind particles impact the surfaces of Mercury & Moonsolar wind particles impact the surfaces of Mercury & Moon

Earth’s MagnetosphereEarth’s Magnetosphere

SolarWind:Electrons, protons, helium nuclei

How Molecules Absorb LightHow Molecules Absorb Light X raysX rays

• ionize atoms & moleculesionize atoms & molecules• dissociate moleculesdissociate molecules• absorbed by almost all gasesabsorbed by almost all gases

Ultraviolet (UV)Ultraviolet (UV)• dissociate some moleculesdissociate some molecules

• absorbed well by Oabsorbed well by O33 & H & H22OO

Visible (V)Visible (V)• passes right through gasespasses right through gases• some photons are scatteredsome photons are scattered

Infrared (IR)Infrared (IR)• absorbed by greenhouse gasesabsorbed by greenhouse gases

Atmospheres & Global Warming Earth and the Other Terrestrial Worlds

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