Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Atmospheric CO2 Since 1750Composition of the Present AtmosphereSlide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Annual Climate in SeattleSlide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Sea IceGlacial IceExample of a positive feedbackSlide 36Slide 37Slide 38Slide 39Satellite-Derived Plant GeographyChapter 1 Introduction to the Climate Chapter 1 Introduction to the Climate SystemSystemThis chapter discusses:This chapter discusses:1.1.Earth’s atmosphereEarth’s atmosphere2.2.OceansOceans3.3.Cryosphere (sea ice/glacial ice)Cryosphere (sea ice/glacial ice)4.4.Land and biosphereLand and biosphereThe Effects of the Atmosphere Blocks ultraviolet radiation Meteors burn Sound waves can travel Birds and airplanes can fly Diffuses heat Scatters sunlight (blue skies and sunsets) Hydrologic cycle Weather and climateThe Atmosphere A thin envelope around the planet 90% of its mass (5.1 x 1018 kg) is within 16 km (10 mi) of the surface (about 0.0025 times the radius of the Earth) Atmospheric motions can therefore be considered to occur “at” the Earth’s surface The basic chemical composition of dry air is very uniform across the globe and up to about 100 km The greatest and most important variations in its composition involve water in its various phases Water vapor Clouds of liquid water Clouds of ice crystals Rain, snow and hailComposition of the AtmosphereDry AirTRACE GASESArgon (.93%) andCarbon Dioxide (.03%)Ozone (.000004%)Water vapor is constantly beingadded and subtracted from the atmosphere, and varies from near0% (deserts) to 3-4% (warm, tropical oceans and jungles)Solid particles (dust, sea salt, pollution) also existGreenhouse GasesGreenhouse Gases• Nitrogen, Oxygen and Argon (99.9% volume mixing ratio) have only limited interaction with incoming solar radiation, and they do not interact with the infrared radiation emitted by the Earth • A number of trace gases (carbon dioxide, methane, nitrous oxide, and ozone) do absorb and emit infrared radiation (as does water vapor)• Water vapor, carbon dioxide and ozone also absorb solar shortwave radiation• Because they emit infrared radiation up- and downward, these greenhouse gases increase the energy received at the Earth’s surface, thus raising the temperatureChanging Atmospheric Composition:Indicators of the Human Influence• 31% increase since 1750: Highest levels since at least 420,000 years ago • Rate of increase unprecedented over at least the last 20,000 yearsCO2CH4N2O• Increased 150% since 1750 to its highest levels in at least 420,000 years• Has both natural (e.g., wetland) and human-influenced sources (e.g., landfills, agriculture, natural gas activities)• Accounts for 20% of total GHG forcing • Increased 16% since 1750 to its highest levels in at least 1,000 years• Has both natural (e.g., soils and oceans) and anthropogenic sources • Accounts for 6% of total GHG forcing • Halocarbons (e.g., CFCs) account for 14%Global, well-mixed greenhouse gas (GHG) concentrations 1000 1200 1400 1600 1800 2000Year 1000 1200 1400 1600 1800 2000YearCO2CH4N2O• Increased 150% since 1750 to its highest levels in at least 420,000 years• Increased 16% since 1750 to its highest levels in at least 1,000 years• Has both natural (e.g., soils and oceans) and anthropogenic sources • Accounts for 6% of total GHG forcing • Halocarbons (e.g., CFCs) account for 14% 1000 1200 1400 1600 1800 2000YearChanging Atmospheric Composition:Indicators of the Human Influence• 31% increase since 1750: Highest levels since at least 420,000 years ago • Rate of increase unprecedented over at least the last 20,000 yearsGlobal, well-mixed greenhouse gas (GHG) concentrations 1000 1200 1400 1600 1800 2000YearCO2CH4N2O• Increased 16% since 1750 to its highest levels in at least 1,000 years 1000 1200 1400 1600 1800 2000YearChanging Atmospheric Composition:Indicators of the Human Influence• Increased 150% since 1750 to its highest levels in at least 420,000 years• 31% increase since 1750: Highest levels since at least 420,000 years ago • Rate of increase unprecedented over at least the last 20,000 yearsGlobal, well-mixed greenhouse gas (GHG) concentrationsAtmospheric CO2 Since 1750Composition of the Present Atmosphere Venus Earth MarsSurface Pressure 100,000 mb 1,000 mb 6 mbCO2 >98% 0.03% 96%N21% 78% 2.5%Ar 1% 1% 1.5%O20.0% 21% 2.5%H2O 0.0% 0.1% 0–0.1%The Vertical Structure of Earth’s AtmosphereThe Vertical Structure of Earth’s AtmosphereFour Four layers: layers: TroposphereTroposphere (overturning(overturning) ) StratosphereStratosphere (stratified) (stratified) From surface to 8-18 kmFrom surface to 8-18 km From troposphere top to 50 From troposphere top to 50 kmkmMesospherMesosphereeThermosphereThermosphere Absorption of solar Absorption of solar radiation by Oradiation by O33 Extremely thin air; very Extremely thin air; very low temperaturelow temperature Extremely thin air; very Extremely thin air; very high temperaturehigh temperatureVertical Structure of the Atmosphere4 distinct layersdetermined bythe change oftemperaturewith heightExtends to 10 km in the extratropics, 16 km in the tropics Contains >80% of the atmospheric mass, and 50% is contained in the lowest 5 km (3.5 miles) It is defined as a layer of temperature decrease The total temperature change with altitude is about 72°C (130°F), or 6.5°C per km (lapse rate)• It is the region where most weather occurs, and it is kept well stirred by rising and descending air currents• Near 11 km resides the “jet stream”• The transition region of no temperature change is the “tropopause”: it marks the beginning of the next layerVertical Structure of the Atmosphere4 distinct layersdetermined bythe change oftemperaturewith heightExtends to about 50 km It is defined as a layer of temperature increase and is stable with very little vertical air motion – a good place to fly! Why does temperature increase? In part because of ozone, formed as intense ultraviolet solar radiation breaks apart oxygen molecules • Near the ozone maximum (about 25 km), there are
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