www.nasa.gov generations throughoffossilfuels. theburning have been creating and modifying clouds for stop precipitating. Thisisproof thathumans reflective, carrymore water, andpossibly atmosphere, which cause clouds to be more be formingsulfateaerosol particlesinthe (SO What theyhavefoundisthatthesulfurdioxide fuel emissionsoncloudformation. an easiertimemeasuringtheeffects offossil clean andstill marine air, where scientistshave ships release theirexhaustintotherelatively Not significantsources ofpollutionthemselves, tostudyingshiptracks. country haveturned Center andanumberofuniversitiesaround the Researchers from NASA’s Goddard SpaceFlight PacificOceanonJuly3,2010. over theNorthern large ships—astheyappeared from Earthorbit vapor condensingontheaerosols comingfrom shows “ship tracks”—clouds formed by water This image,madewithdatafrom theAquasatellite, sources ofSO emissions from continuously volcanoes, erupting such as those in Hawaii, human and otherhumansources are an “all day, every day” occurrence. Even withSO the amountreleased somevolcanic during eruptions,emissionsfrom power plants Dobson Unit would be0.01 millimeters thick. While this may seemsmall compared to a singlelayer attheEarth’s surface atatemperature ofzero degrees Celsius, one Just imagineifyou couldcompress alloftheSO recorded inDobsonunits—aunitofmeasurement columnardensity. ofatmospheric fromworld bothnatural sources andman-madeemissions. These measurements are track SO likeInstruments theOzone (OMI)onNASA’s Monitoring Instrument Aura satellite, climate change. it canform sulfate aerosols thatpersist for oftimeandcancontribute longperiods to precipitation. explosive Somevery volcanoes sendSO tiny sulfate calledaerosols thatcanalter particles, ofcloudsand thebrightness plumes, inashandSO rich in theoxidation ofnaturally sulfurgases, occurring asinvolcanic eruptions. Volcanic the combustion ofcoal, fuel oil,andgasoline (since these fuelscontain sulfur),and SO naturally occurring. of SO S Sulfur Dioxide 2 2 ) released from ships’smokestackscould is a precursor to acid, a major constituent of acid rain. sulfuric It is produced by soluble, acidicgas. SO ulfur dioxide 2 canresult intemporarybreathing impairment. Itisbothhuman-generated and 2 intheatmosphere allowing scientiststo compare SO 2 far exceed natural sources. (SO summit, andblues,greens, andlavendersfartheraway. the volcano,itsintensitydissipated,evidencedbyred huesnearthe concentrations appear in lavender. As the SO The greatest concentrationsofSO SO OMI onboard theAurasatellitewasabletomeasure concentrationsof blue-gray, withless distinctmargins. over thevolcano.Compared tothenearbyclouds,volcanicplumeis volcanic summitmaybepartoftheplume,orcloudscollected perseveres farnorthwestofthevolcano.Opaquewhitepuffs nearthe as itexpandsandmingleswithclouds.Althoughfaint,theplume 2009. Inthisimage,thevolcanoplumecanbeseendriftingwestward Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite April 14, The image(right)wasmadefrom datafrom theModerateResolution extended farwestoftheislands,overPacificOcean. eruption alsoproduced asubstantialplumeofsulfurdioxide(SO Galapagos Islands erupted, producing an ash plume and lava flows. The In earlyApril2009,LaCumbre Volcano inthe onIslaFernandina 2 )—a colorless,toxic water odor—isavery gas withasharp 2 from theLaCumbre Volcano onthesame day(imagefarright). 2 2 irritates theeyes, nose, andlungs. Highconcentrations , are ahazard to aviation. SO July 3,2010 Pacific Northern 2 inacolumnoftheatmosphere into 2 appearinred, andthesmallest 2 into thestratosphere, where 2 plume moved away from 2 canbetransformed into 2 emissionsaround the 2 ) that N April 14,2009 Galapagos Islands,Ecuador 2 50 km

arrows depictingdominant winddirection. represented here inpurple,withsmall spacecraft. TheconcentrationofSO Infrared Sounder(AIRS) on NASA’s Aqua measurements from theAtmospheric end ofMay2011.Theimagesare from the GrímsvötnvolcanoinIcelandat and transportofsulfurdioxide(SO These three imagesshow theemission May 22,2011 ash plume La Cumbre volcano Isla Fernandina Isla Isabela 2 ) from 2 is produce acidrainandvolcanic smog,orvog. It alsodissolvesinwatertheatmosphere to breathe, particularlyforpeople withasthma. SO and west,carriedbywinds. and thenthousandsofkilometerstotheeast As thedayspass,plumespreads north May 23,2011 2 near the surface of Earth can be harmful to

Latitude 2°N 4°N 6°N 6°S 4°S 2°S 0° 110°W

Pacific Ocean 105°W 100°W Longitude can corrode anddamage aircraft windows. necessarily poseanimmediatehazard toaircraft operations,it While SO 0 May 24,2011 Sulfur Dioxide Isla Fernandina 2 aerosols athigheraltitudes afteraneruptiondonot 95°W 5 (DobsonUnits) Galapagos Islands 90°W 10 Units (red). by 13kilometers)reached valuesof3Dobson or pixels—oftheimage(eachblockisabout 24 the villageofRadetski.SO one nearthetownofGalabovoand complex’s large powerplants, coal-burning OMI appearintheairdirectly overtwoofthe The highestSO Iztok ComplexinBulgaria,onJanuary12,2009. Europe, power plantsinEastern theMaritsa dioxide (SO The imageaboveshowsmeasurements ofsulfur datasets forscientiststouse. in goodagreement with oneanother, providing consistent that theinstruments,detectingSO in theatmosphere. Theirstriking similaritiesprovide evidence instrument, OMI.BothimagesrevealofSO similarpatterns however, reveals datacollectedbyadifferent satellite image from theimageseries shownontheleft.Thisimage captured on May 23, 2011—the same day as the middle The image below of the Grímsvötn volcanic eruption was Greece 2 ) intheairoveroneoflargest Galabovo 2 concentrations detected by concentrationsdetectedby Bulgaria Aegean Sea 2 inthree “blocks”— 0.0 Radetski Sulfur Dioxide 2 inouratmosphere, are Turkey 1.5 Sea ofMarmara

cloud (Dobson Units) Black Sea

2 3.0 Galabovo Aegean Sea exhaust plumes snow Radetski around Noril’sk onApril9,2006. of theforest—closest tothesmeltingfacility. Theimageaboveshowsthearea concentration ofsulfurintheirneedlesoccurred inthemostheavilydamagedparts kilometers) oftrees haddied.A2003studyfoundthatthetrees withthehighest death increased steadilyeachyear. By2007,atleast1.2millionacres (4,850square testify totheacidrain’s impactdownwindofthesmelters.Startingin1968,tree Landsat 7satellite.Expansesofdeadforest (revealed inpinkandpurplecolors) above imageshowsthearea around theNoril’sk miningfacilitycaptured byNASA’s Large amountsofSO June-August from 2005-2007. by OMI.Themeasurements showninthisimageare averageddataforthemonthsof The imageaboveshowsconcentrationsofSO 0.5 Lake Pyasino Sulfur Dioxide smelters Sea ofMarmara National Aeronautics and Black Sea Space Administration 1.75 2 cancauseacidrainandaffect thelocalenvironment. The (DobsonUnits) Noril’sk Melkoye Lake 3.0 from snowontheground (brightblue). distinguish cloudsandexhaustplumes(white) same day. Itusesvisibleandinfrared lightto by MODISonNASA’s Aquasatelliteonthat This false-colorimageisfrom datacollected gases continuallyfilltheairsurrounding thesite. coming from thepowerplant.SO The imageatleftreveals exhaustplumes 2 from theNoril’sk facility, measured amounts ofthesemetals, lytic converters.Significant on palladium to make cata tomobile manufacturers rely products asubtlesheen. Au rely onnickeltogivetheir Stainless steelproducers the entire sulfurdioxide(SO oxide each year—more than 1.9 milliontonsofsulfurdi and the process produces the metalsfrom sulfide ore, lution. Minersmustextract of theworld’s worstairpol yet ithasalsocreated some of roughly 200,000people, facility supports a population smelting facility. Themining one place:Siberia’s Noril’sk along withcopper, comefrom output ofFrance. NW-2011-10-093-GSFC 2 and other andother 2 - - - - SO2)