“Suspended” Space Shuttle EndeavorCourse AnnouncementsAssignmentsQuiz 3 ResultsChapter 7Earth’s General StuctureAtmosphere – Different than expectedOrigin of Earth’s AtmosphereOrigin of Earth’s AtmosphereOrigin of Earth’s AtmosphereOrigin of Earth’s AtmosphereEarth’s Atmosphere - CompositionEarth’s Atmosphere – Lower LayersEarth’s Atmosphere – Lower LayersTroposphereConvection in TroposphereConvectionStratophere – The calm ozone layerThe Ozone HoleThe Ozone HoleWhy is the sky blue?Why is the sky blue?Why is the sky blue?Why is the sky blue?Why are sunsets red?Surface HeatingGreenhouse EffectGreenhouse EffectGreenhouse EffectClimate Change & Climate ScienceClimate Change & Climate ScienceAtmospheric CO2Atmospheric CO2Atmospheric and Climate PhysicsClimate PhysicsAtmospheric and Climate PhysicsClimate ChangeClimate Change“Suspended” Space Shuttle EndeavorImage Credit: NASA/Crew of Expedition 229 Feb 2010TroposphereStratosphereMesosphereCourse Announcements•Quiz 3 available for collection•ESA’s ExoMars Trace Gas Orbiter (TGO) successfully in orbit•ESA’s ExoMars Schiaparelli Lander likely did not survive the landing, but that wasn’t the point...–Entry, descent and landing Demonstrator Module (EDM) designed to test European Mars landing technologyUpcoming Class Schedule:•Quiz 4 on Monday 24, October•Exam 2 on Friday, 28 October–Will be releasing study materials and planning study sessions (more info. to come soon)AssignmentsReading Assignments•No new readingParallel Lectures•CC Astronomy – Episode 11: The Earth(watch if you haven’t yet)Mastering Astronomy•Chapter 7 Homework[Due Monday, 21 October at 11:59 PM EDT]Quiz 3 ResultsBest quiz (grade-wise) yet!•Typo in Gas Giant Planet formation hypotheses question (Core-collapse -> Core accretion)–Credit given to everyone•Very few instances of sharing Bonus Point Keyword Dumbledore. Thanks for the honesty.Raw w/ Bonus PointMean 7.8 8.7Median 8.0 9.0CHAPTER 7The EarthEarth’s General Stucture•Inner Core: 0 - 1300 km•Outer Core: 1300 – 3500 km•Mantle: 3500 – 6350(ish) km•Crust: 5 – 50 km thick–Oceanic Crust: ~5 km thick–Continental Crust: ~ 30 – 50 km thick•Hydrosphere: All water•Atmosphere: Crust – 100* km•Magnetosphere: >100 km* The Kármán Line… flight not possible. Atmosphere technically extends to infinity...Mass: 6 x 1024 kg (5.97 x 1024 kg)Radius: 6,400 km (6378 km)Avg. Density: 5500 kg/m3 or 5.5 g/cm2Atmosphere – Different than expectedGas Formula % by VolumeMain ConstituentsNitrogen N278Oxygen O221Argon Ar 0.9Trace GasesCarbon Dioxide CO2~0.03Other The restVariable AmountWater Vapor H2O 0.1 – 3.0The composition of our atmosphere is not like our expectation of a secondary atmosphere dominated by CO2Earth’s early Secondary Atmosphere is expected to be mostly CO2 (about 95+%)…How did it becoming nitrogen dominated?Where did the oxygen come from?Origin of Earth’s Atmosphere•Earth’s gravity too low to keep the primary atmosphere of hydrogen and helium inherited from the Solar Nebula •Volcanic outgassing released gases trapped in Earth’s interior create a secondary atmosphere–Water vapor, methane, CO2, sulfur dioxide, and nitrogen compounds (N2, Ammonia, nitric oxide, etc.)Not like the expected Secondary Atmosphere… what gives?Sarychev Eruption from ISSOrigin of Earth’s Atmosphere•Volcanic outgassing of water vapor, methane, CO2, sulfer dioxide, and nitrogen compounds (N2, Ammonia, nitric oxide, etc.) generate Earth’s Secondary Atmosphere–Expectation is primarily CO2 atmosphere…–Our atmosphere has significantly changed since then•Photodissociation (sunlight, primarily UV light, breaking apart molecules) broke these molecules apart forming…–Inert (non-reactive) N2 forms and builds up–Loss of hydrogen atoms to outer space•Water condensed into oceans and dissolves much of the CO2 and sulfur dioxide.•Remaining CO2, sulfur dioxide, etc. reacts with surface rocks and becomes incorporated into the rocksAltering the Secondary AtmosphereOrigin of Earth’s Atmosphere•Oxygen is very chemically reactive, so why here?–Requires constant replenishment•Life appeared in the oceans some 3.5 billion years ago, but it wasn’t until about 2.5 billion years ago that photosynthetic organisms (cyanobacteria) released oxygen (O2) into the atmosphere.–Transition to dominance of photosynthetic life and oxygen in the atmosphere called the “Great Oxidation Event”Still need OxygenCyanobacteria Bloom Credit: NASA/MODISCyanobacteria Credit: Queen Mary Univ.Origin of Earth’s AtmosphereSummaryNH3UV Light(Photodissociates Nitrogen Compounds)H NNH3NHN2Nitrogen (N2) builds up in atmosphereFree hydrogen escapes to spaceCO2 & SO2CO2 and SO2 dissolve in oceans and become part of the rocks2.5 Billion Years ago (Gya) cyanobacteria generate O2 via photosynthesisO2Summary: •CO2 & SO2 become part of oceans and rock•Light splits nitrogen compounds and forms N2, which builds up in atmosphere•Photosynthetic life provide O2 to atmosphereLeft with N2 and O2 rich atmosphereEarth’s Atmosphere - CompositionGas Formula % by VolumeMain ConstituentsNitrogen N278Oxygen O221Argon Ar 0.9Trace GasesCarbon Dioxide CO2~0.03Other The restVariable AmountWater Vapor H2O 0.1 – 3.0Our Oxygen makes us unique99%Earth’s Atmosphere – Lower LayersIonosphere/Thermosphere (80+ km)Ionized molecules and free electronsMesophere (50 - 80 km)Stratosphere (17 – 50 km)Contains Ozone LayerCalm air where planes flyTroposphere (0 – 17 km)Convection OccursPlace where weather is80 % of the massTemperature (K)100 kmEarth’s Atmosphere – Lower LayersTemperature (K)•Boundaries between layers occur at temperature inversions–How temperature changes with altitude switches•Stratosphere increases in temperature with altitude due to ozone (O3) absorbing UV sunlightTroposphere•In the Troposphere, air is constantly being moved around through convection, driven by Earth’s warm surface.•Convection is the transfer of heat from one place to another through the movement of a gas or liquid.Where weather happensWarms UpCools DownConvection CellConvection in TroposphereIn Earth’s AtmosphereSunlight HeatsSurfaceEach circulation unit called is called a Convection CellHeat INConvection•Earth’s Surface warms the air above it.•This warm air is less dense (thanks, Ideal Gas Law), and therefore rises, i.e., it becomes buoyant (wants to float
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