2. Our Physical World: the Lithosphere, Atmosphere, and Hydrosphere The Solar System: formed approximately 4.6 billion years ago Mercury Almost no atmosphere Extremes of hot and cold Extensive evidence (craters) of early bombardment indicates its surface is formed by external factors Little or no magnetic field Venus Similar in size to earth Atmosphere mostly made of carbon dioxide with sulfuric acid clouds Evidence of volcanism No surface water or indication of flowing water in the past Extremely hot Mars Diameter: 40% of Earth?s Thin atmosphere with some water and no oxygen Weak magnetic field in the past Volcanism and geological activity Mostly cold, typically under freezing Gas Giants: Jupiter, Saturn, Uranus, and Neptune Largely gaseous Interesting multiple moons surround each planet, which may contain water Earth?s characteristics critical for life A chemically complex atmosphere containing large amounts of oxygen Ozone helps protect life on land from harmful UV radiation Disequilibrium: the constant renewal of oxygen by Earth?s life forms Vast amounts of liquid water Distinct continents with varied geography No evidence of early bombardment Abundant life that shapes the planet History of the Earth There are few signs of the earth?s early history because it is constantly changing Continental drift Glaciation Water movement Wind erosion Plates shifted around the asthenosphere over millions of years Pangean (229 million years ago) Trassic (200 million) Jurassic (133 million years ago) Cretaceous (65 million years ago) The Solid Earth Inner core Solid iron Outer core Molten Generates magnetic field Mantle Asthenosphere Plastic-like Continental drift Plate boundaries Divergent boundary Typically happens at the bottom of the ocean Magma seeps up beneath ocean Transform boundary Earthquakes Convergent boundaries Subduction Denser plates subduct, where oceanic crust meets continental, the oceanic subducts, creating volcanoes Volcanoes This explains why ocean crust is so young, they are constantly being subducted because they are more dense Uplift Mountains Lithosphere Crust Continental curst Around 1/3 of Earth?s surface Less dense Older rock Oceanic crust Very dense Younger rock Uppermost layer of mantle Geothermal energy Fossil fuels Nuclear energy Plate Tectonics Convection cells in the asthenosphere move the plates slowly Convection currents are caused by the heating and cooling of the mantle in the asthenosphere Convectional heating in the mantle provides force Rock types Igneous rocks formed from the crystallization of molten lava Balsatic (Basic) Melted mantle Rich in calcium, magnesium and iron Acidic Recycled crust Rich in silicon and aluminum Sedimentary rocks form from the accumulation of either eroded or biologically produced materials Limestone: cemented shells of marine organisms Shale: fine grain deposits Sandstone: cemented coarse sands formed in high energy environments like beaches Coal: organic deposits formed in swamps Metamorphic rocks formed from the alteration of igneous or sedimentary rocks under great pressure or heat Often reflect chemical character of the parent rock Marble, from limestone Environmental importance Contaminant transportation depends on the rock type beneath the contaminant zone Rocks have effects on groundwater, filtering and contamination Case Study: Bangladesh Bangladesh?s wells were contaminated with arsenic Rocks under the wells contained arsenic, which contaminated groundwaters Case Study: North Carolinian rocks 300 million years ago: continents collide to form ancient Appalachian mountains 220 million years ago: mountains begin to erode to form North Carolina?s sedimentary coastal plain Durham lies atop an array of rocks formed during the collision of North America with North Africa Hydrosphere Oceans contains 97.2% of the planet?s surface water Water has a high heat capacity Regulates Earth?s heat temperature Ocean temperatures are much more stable than land temperatures Vertical Profile Surface Zone (2%) Stirred by the wind Similar density throughout More Oxygen Pycnocline (18%) Intense drop in ocean temperature Density increases dramatically with depth Deep Zone (80%) Sluggish, dense water More nutrients Horizontal Profile Neritic Zone ?Green Water? Shallow waters near land 98% of ocean biological actibvity Only 2% of ocean area Oceanic Zone ?Blue Water? Importation to the circulation and transfer of heat Marine Habitats Pelagic zone: open water, sea surface Benthic zone: seafloor Ocean Surface Currents Major Gyres are driven by various factors Wind The Spinning of the earth Temperature Salinity-driven changes in water density and gravity Equatorial water is heated and driven west Because water moves pole ward as it encounters continents, it brings warm water to the east sides of the continents Water cooled at the poles circulates southward or northward along eastward edges of the continent Case Study: North Atlantic Gyre and the Gulf Stream Water heated along the equator in central Atlantic moves west It becomes deflected north into the Gulf of Mexico Warmed in the Gulf, the water moves as a narrow current up the east coast of the Untied States It is then deflected eastward Ocean circulation occurs in three dimensions Vertical movement largely driven by density changes resulting from: Changes in temperature Changes in salinity due to differences in evaporation and precipitation Atmosphere The atmosphere is quite thin compared to the earth Magnetosphere Influence of the Earth?s magnetic forces extends out tens of thousands of miles Shields earth from deadly effects of solar wind Thermosphere H, He, and O Very thin Space shuttles fly here Temperature reach 1500°, Ionosphere: Upper portion Region of ionized gases influenced by magnetic forces and the sun?s radiation Northern lights occur here Mesosphere N2, H2O, O2, and O3 Much colder -100° Stratosphere Ozone layer 20 km Shields troposphere and lower earth from UV radiation Planes fly in the stratosphere because there is no weather Troposphere Gravity pulls most air molecules close to the Earth?s surface, so our density is greatest near the surface Atmosphere pressure is greatest near the surface because emost molecules are above Atmosphere pressure reflects the density of air molecules Chemical composition Nitrogen (78%) Oxygen (20.95%) Argon (.93%) Temperature: -50° to 40° degrees in Earth?s surface Weather occurs here because of the movement of hot air in currents Almost all of the water in the atmosphere is in the troposphere Water in the atmosphere Evaporation, condensation and precipitation drive the water cycles Absolute humidity: total water content Saturation humidity: among of water that air can hold Temperature limited, goes up with increasing temperature Relative humidity: the percentage degree to which the air is saturated As temperature rises and falls during the day, relative humidity falls and rises in response If it drops to the dew point, dew forms If it is below freezing, frost forms Dew point: the temperature at which air containing a given amount of water reaches 100 percent relative humidity Adiabatic cooling: air pressure drops and air is cooled Air rising by convection becomes less dense, cools, and eventually sinks in convective circulation Adiabatic lapse rate: rate of cooling dependent on the dew point When it cools to dew point, rain drops may condense Rain Shadow Effect: Air moving up a mountain side decreases in density and cools The opposite occurs as air descends the other side of the mountain Warm and Cold Fronts Warm Front: warm air rising over cool air creates moderate precipitation Cold Front: cool air wedging under warm air forces warm air upward, causing heavy precipitation Global Convection Currents Hadley Cells Air rises at the equator, falls at 30° latitude Ferrel Cells Air falls at 30°, rises at 60° Not as defined and predictable as Hadley and Polar Polar Cells Air rises at 60°, falls at 90° Rainier climates occur by the equator (hot and hot) Dryer at 30 (cold and cold) Corialis effect: the planet?s rotation causes land at the equator to spin more quickly than temperate land This causes north-south winds to appear to be deflected and to curve The earth?s surface topology also has some effect Air Circulation The Earth is tilted at 23° on its axis so that the position of greatest solar heating shifts through the seasons, as do the various wind cells and climate zones El Nino and La Nino Ocean circulation In an El Nino event, warmer water pushes east Winds weaken and warm water sloshes to the east This prevents the cold upwelling that brings nutrients, bad fishing then occurs This creates warmer and moister airs in the Americas They occur irregularly and usually one or two years La Nino is where cold water pushes west Both atmospheric circulation and oceanic circulation tend to move hot air to the poles, exasperating the effect of climate change in polar regions The Hydrologic Cycle (page 205) Air Pollution Classifications Anthropogenic Natural (volcanoes, Forest Fires, Dust storms) Point Source (factory, power plant, smoke stacks) Non-Point Source (emissions from millions of cars) Primary Pollutant: emitted into the troposphere in a directly harmful form (soot, carbon monoxide) Secondary Pollutant: produced via the reaction of substances added to the atmosphere with chemicals already present in the atmosphere (ozone in the troposphere) Six Criteria Polloutants CO NOX VOCs: Volatile organic compounds, meaning they include Carbon SO2 PM Pb (lead) dramatically reduced with regulations Acid Deposition (Acid Rain) Sulfur Dioxide and Nitric Oxide react with water, oxygen and other oxidants to become sulfuric acid and nitric acid Rain is normally slightly acidic because of CO2 in the atmosphere Acid rain transcends borders 1970 Clean Air Act Sulfur Emissions have decreased due to Scrubbers to clean smokestack Legislation and a market-based emissions trading scheme But nitrate pollution has risen slightly, and acidification is not being reversed as many have hoped Stratospheric Ozone Depletion Chlorinated Flourocarbons (CFCs) persist in the stratosphere, splitting oxygen atoms off ozone to form oxygen UV radiation splits CFCs to react with the free oxygen molecule CFCs initiate a catalytic reaction Chlorine, the catalyst, is not degraded in the process (CFCs also contribute to global climate change) The Ozone hole was detected over Antarctica The Montreal Protocol 180 nation restrict CFC production Globally There is still uncertainty on the current status of ozone depletion; there is not clear trend on the ozone hold closing, but it doesn?t seem to be getting smaller either Ozone hole: centralized depression, not dissipated all the way through the ozone layer Smog Industrial smog: Burning sulfur-rich oil or coal creates SO2, SO3, sulfuric acid and ammonium sulfate Burning carbon leads to CO2 and CO Photochemical smog: Smog from the reaction of sunlight with polloutants ?Brown air smog? Contains troposphereix ozone, NO2, VOCs, and more Nitrogen is a key component here, nitrix oxide starts a chain reaction Reaction with sunglight, water vapor, hydrocarbon, results in over 100 secondary polloutants Thermal inversion: a natural occurrence that can exacerbate air pollution locally Inversion layer: band of air in which temp rises with altitude Cooler air is trapped and can?t mix This can occur in cities in valleys Indoor Air Pollution Indoor air spaces have more pollution than outdoor spaces United States citizens spend 90 percent of their time indoors Clean Air Act Legislation 1970 Set stricter standards then previous laws Imposed emissions limits Provided research funs Enabled citizens to sue violating parties 1990 Strengthened previous regulations Introduced emissions trading for sulfur dioxide Massachusetts v. Environmental Protection Agency: Supreme Court ruled that the EPA can regulate CO2 and other greenhouse gases as air pollutants
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