Severe Weather MET 4300
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This 15 page Class Notes was uploaded by Mr. Eladio Hettinger on Monday October 12, 2015. The Class Notes belongs to MET 4300 at Florida International University taught by Staff in Fall. Since its upload, it has received 17 views. For similar materials see /class/221790/met-4300-florida-international-university in Meteorology at Florida International University.
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Date Created: 10/12/15
1312008 Divergenceamp A C Dlnes Com ensatlon Convergence p 1 coumnsme Exam E n D s a o o Convergenceover Smceawrcan tbe 4 a created ur deslruyed areasufmnvergence quot meme an dwergencepruduce mmnm mum venma mutmn 7 Cyclonically Curved Flow Ageostrophic ow 1312008 Effect of Curvature on Meandering Flow Swerve151nm 7 ii g i 55 cmwin franc Jet Streaks and Ageostro A 1 mm uwnm un quotSMV a a a u z m m N T a m M quot quotquot A ma mb Mlvsluswnzr mv luswts wsmi m n Va rticity Vorticity Stretching w a msmhutmn ahmmmtv 5 stretched vertmev n m mm m rgm m re mmvhmted m MAX 5 curved he damman anar grab mm ranta Cvdanehrm amquot Bemmesma Vammtwst m m mm mm m i evarm en use 9 e swam 3M1 de Wquot W mew mquot mm mugnmmmmamm a momma m Andtheswvhngwmdmtreases 25 memmquot stretmmgmwanetavwrtm mmmuunmm m erm matmnsmamsaurm munapwmmm m am tymtheatmasphere 5 quotW S M39 Vurtmtvsumsmrgwarbthe meme W n v mm a ammxm atheran WWW anamsthemam smka mm m m a wrtmtviamngthhwrtex mm d S uxshmi Combined Effects of Curvature and a Jetstreak mmwmmamemm JEtStreakS Mawmares aw vthanthewmd5athataxrmavesthmughthevmem mm weH d med 4 quadrant pattern a ascent and descent Mm r mm and Mr m u Dlvnmmce c Convergence nd Gun3mm Gman Jsmusak 13 12008 Often Dines compensation does not fully compensate FrIctIon In Cyclonlcally Curved Flow Hawaiian c Top down View Sula View c r l ivugem Alan Nu gain of in molecules wmgnl av air may ara Na IDIE Bl air mo acuies weighl oi av own area i i l Air column lling Ill II bottom A 39 Surface yressurc will 5mm A incrcnsc win time Friction in Antiyclonically Curved Flow Fr39Ct39onal In ow a Real CVC ne Top down View Side View 7 evacuating at bottom Surface pressure will Effects of Convective Heating and Radiative Cooling m min quotmu mm m n m ryltm 0 4 u m w m 9x IJ Nu mm Niam M mm m 1312008 Role of Updrafts amp Downdraft in Development was k 7 LAeWeHH imam 4 Summary Dwergence and convergence causevemcz mutmns Dmes Compensztmn Dwergence above eanvengenee and cu vengeneeaaaveawe ence Ageuslmphm uw m Jmstrezks Emma s upper dwergence and cume ence Areas nne awsduetaeurvamreaeeexerauamnman Fuur quadrant made a v gen nd nsmg matmn m HEM entrance ana Mt em u Derdwer oe a u oer eamergenoe and smkmg Nanaquot m e entrance and ght em anaaverg Vumuty made a zwr uwmgthmugh a emreakprawaes a cunmse a W nueznd wergence mechzmsm furfurmztmn of fronta cydunes FOR NEXT TIME 1302008 Pressure and Wind in the Atmosphere are Coupled What Forces Act On the Wind Newton s Laws of Motion Govern the Wind 1 Every object in a state of uniform motion or Pressure Gradient Force at rest will remain in that state of motion Coriolis Force due to Earth39s rotation or rest unless an external force ls applied Friction which always acs to Slow moving 2 Force is equal to mass times acceleration objects Accelerat39on and force are vecmrs39 Apparent force required to move air in curved 3 For eVery ECHOquot there 395 an equal 3quot paths but only if the radius of the path is opposite reaction small The first two forces are most important Note The book39s explanation in enns of angular momentum is Pressure Gradient Force COTiOIiS Force inirpamrriom In a rotating reference lrame objects lollnwing straight paths appearto move in curved paths Net Lower Force rotating planet once we take it Pressure Pressure lntn account I de ects moving objectstothe right nltheir motion Totheleltinthesouthern hemisphere The Coriolis loree s magnitude is proportionaltothe object s speed nlmntinn and the o1 PGF trie to squeeze air toward lower pressure 1302008 Geostrophic Balance Balanced W nds at 500 mb L fpressure gradient force 5340 m w r geoslropluc wind 5 50 m Conclls Force annalsamermarm am m M amasprmmmm How does the wind et to be g Effect of Friction balanced L 39e furc mm m pressure gradl m e 1 d 1012 mb quot quot V I n 1016mh quotcm Corlolls Force Slnwswld thmpcrus H srnngulhanIheCnnnlIsmrce causng quotWigwam wlndsln hlnwlnwam lnwa nm um Temperature Gradinets and 3 55 vertical Thermal Wind upward pre sure Balance gradient force A air purcrl in g mm lmlunu w x E i canstan rassu lroplcal polar laliludes laMudes 1302008 Jet Streams a d Horizontal Temperature Gradients Summary Newton s laws of motion Forces Pressure Gradient Coriolis Friction quotCentrifugalquot Geostrophic balance between PGF amp Co Friction causes crossisobarflow to low pressure Hydrostatic balance Vertical pressure gradient alances gravity Thermal wind Horizontal temperature gradients lead to increasing height gradients aloft and shear of 39 win Strong temperature gradients along surface amp upper fronts cause jest strea ms FOR NEXT TIME Read Chapter 7 Air Mass Thunderstorms All convection requires 7 Conditional instability 7 Lift or heating 7 Moisture Airmass TR have 7 One updrartlt1o m s1 7 A few km across 7 Extendsthrough the depth ofthe troposphere 7 Low shear 7 Moderate instability CAPE lt 1000 well de ned life cycle 7 Isolated single cel s 7 Move nearly with the surrounding wind Cumulus Life Cycle llihrium Laval s E i Leveioirree convulion ii quot 339 353531 cum Cumulus Life Cycle Kinds of PreCIpltatlon Rain Liquid water drops gt 05 mm in diameter falling Cumulus m the s El hfgl zr h s quwm Drizzle Liquid water drops lt 05 mm in diameter falling temperatures eeleer 39om the s 7 May a thanEW Mat re 7 Nearmaxlmumhelght 7 lxedlceand alnieachesgiuund ume duwndia s pating Virga Like rain but evaporates before it reaches the ground 7 Virgais a hydrometeor but it isn t precipitation Hail More or less spherical ice gt 5 mm in diameter Graup I More or less spherical ice lt 5 mm in diameter Note that the boundary between Hail and Graupel is 10x larger than the bounda between Rain and Drlzzle Snow Ice crystal deposited directly from vapor or aggregates clumps of crystals Note that the boundary between Hail and Graupel is 10 times larger than the boundary between Rain and Drizzle Diss ullapslng 7 i iedumlnatelylcewheieculdei an we 7 i iedumlnatelyduwndia s 7 ainin hard Duvvridraft air rurrns uld nutrluws r gustrruntsthatmtriggernew e s u c Terminal Velocity Hyrdumeteurs fall speed rs a balance between thetreh ahu gravrty e Cluud particles rhrhererhsr a rh squot ltr A 5 r 1 e Srheether hyurerheteers What Happens in a Cloud upuren leads in caalmg ehu mhuehseuuh evapmalwe malmg tar2 davmdvans What are clouds made of um mnnurnns but maintained ermm drnvlaseeabaul up unes mallevlhan rehurapsh e mean urr u men ue nrr m diameter uuuu draplel rerneuuh h Smevsalmaled enthruueh Mwtzrv or menu nuclallnn Water uraps m we errsers rngmurn h pure invalve da vka aeehstthe suneee tensan r uu dmplels nun scratch because the ammml at smevsamralmnlr when generallv dues not ueeur hthe mmaspheve Heterogeneous nucleation Water drups er ree crystals form from the vapur eh some sun of substrate ur by soaking mm a salt particle Furwetable nucleh Water attaehes tn the surface Furh greseepre huelehwater suaks mm the surface and may actually dissulve the nucleaus What makes a guud Cloud Condensation Nucleus CCN7 e R easunablyblg luvanaemsulpavlmle e Easilywelable n1 urn m suluble m m n Overland muemuu CCN s m cm3 typreauy peeerhe aetwe at 1 super aturatmn Overthe DEEans ltmu CN errrltypreauy became active at 1 supersaturatmn Growth of Cloud Droplets by Diffusion Thecluudbemmessupersaluvaled Walevvapuvdilluseslmmhlghvapuv r densn lu luwvapuvdenslly Pale rh ssgvuwlhlspmpumunal a ea e rsa u alun Raleulgvuwlh etraurus e 7 e Area lsJavupumunal lu raurus square e 39 e Vulumelspmpuvlmnalluvadlus 39 same u euheu u e Radiusgmwlhlsmvevsel 39 prepenpnaneraurusrtset 39 Thuslheve rs awellrde ned hrhrt I M at mean urn ter d lusmnal gvuwlh mm Growth of Warm Rain WarmR 39 Fallslvumcluuds where T gtch lhvuughuul nennversinn Atew druplels eehue vandumly and merge becummg largevlhan the ethers Hyurerheteerstau neartheh levmmalvelumly aslheylalllhmughlhe cluud Called Collision coalescence CollisionCoalescence Druplets bump intci eacn utherarld merge tci make blgger drups Terminal yelcicity E 5 m s l rcir a lmm rain drup cirtne largerdrup alluvvs it tci uvertake and capture clciug druplets Sume ur all ertne terminal yelcicities may be less tnan tne updrafts yelcicity sci that all ertnis can be mciying upward a least urltll tne drups getle coalescence ef ciency tracticin er drups urdruplets in tne cene that actually merge Witn cellectcir drup yaries rrcim u 2 mr small druplets tn gt i rcir drups that are nearly tne same size Really blg drups gt 2 mm break up and pieces are sum mes carrled back up intci tne cluud rcir ancitner gci Because ertne bruader initial druplet dlstrlbutlurl cec vvurks Witn a yengeance in trepical cumull Satu ration Vapor Pressure Over Ice Vapor Pressure nub Vevor DreSSJre over me is luwertharitha m wata at the e e ature s n as xi 4 4n Yempzvaluve Del eeivmrnaeeenpiaees Am ual neezine nuclel mri MixedPhase Clouds Tlt0 C an ireezine arid canden tlan Eenerallv Emma nuclel to start the Process Natural clouds naye plemv m candensatlari nuclei iuuiuuurner hm iew weenng nuclel i g canseeuenilynanyeauescaieer From me growth at snawinai melts ta taml min Ri ming Starts with a vapor grown ice crystal Falling through a supercooled cloud 9 a 392 mg a as a a N a a 3 Forming spongy ice This is how graupel forms Wet Growth or Wet Riming Temperatures gt 5 C Latent heat released byfreezing kee s hailstone at DEC Coated with liquid water 7 Same freezes 7 Same is shed as drups at va Private Lives of Hailstones Updra s in Cb s are cirten 5M strengertnan nygrcimetecir terminal yelcicities erming multlple layers at clear and spungy ice ln yery strung updrafts nailstcines can get really blg Curreyyille KS ZZJUNEIB e 18 cm diameter 7 75m gm original nniim crysiai Aggregation Faihng fruzen Eigy saggy akes ys mambnu dust Precipitation Formation mm in a suwmba mm Wain Summar Review ciuud geumeivy m veiaimn in LCL LFC amp EL Au MassTbunuemmms vequwe iuw may and mudevaie in abihiy Liie cycie my many rm be m Pveupiimmn Manner Mixed up a davmdvans same be and bbbbyam Dissipaiinngvedaminan v davmdvansy giamaied mummy ham Pvempiiaimn snub Srm Tevmmaiveiumiymbaiance bemeen gvaviiy mamquot Hydvumeieuv gmwlh by d iusiun is hmiiediu man ym Wavmvam gvuws by auiucunvevsmn and cuihsmn cuaiescence Eeygemanindeisen pvucessmice scayengesyabbmbm supevcuuiedh um Haii and gvaupei gvuw by WE ampdvy Hmmg and aggvegaimn in 51mg updva s haii can vecyciey becummg iayeved 412008 Lightning Effects Cause many forest fires Damage buildings and start structure fires Kill 75 people a year US Lec i39 e 32 ngh mg 7 April 2003 Injure about 8 X as many But official reports indicate 25 injuries per One reported injury per 39 F 114000 strikes 77 39 a Earth s Fair Weather Field Maintained by Thunderstorms ELELIROleL L o4a f l h l zomc CUFAFH NY Hi 39 i 5 v J I l v 7 ma wumga i nun wsnmm Eirnmc ViELDlH nunc mini ll wr DSCNAHhtth Book39s View of TR Electrical Structure charge sepa ration Induction Interface mum M w r 33 m 1 mmquot 5 n F v n V 26539 mm quot9quot Mn 412008 Lightning Flash Lightning Flash 100 Flashess worldwide Initiates when the eld exceeds 13 x 105 Vm Peak current is 15000 to 30000 Am eres Conducting channel is 23 cm in diameter And is typically 5 km long Peaktemperature is 15000 K Total charge transferred is 3 30 Coulombs A flash may be composed of 130 strokes 35 is typical Another View 2 msec Remember a Flash may 60 use comprise many Strokes l msec 1r miic khan user l l 412008 US Lightning Flashes l E 5 quoto 51 l 393 lt Ilia DISTANCE km quotJ 3 J 6 9 unmet per minnow net eai US Lightning Fatalities US Lightning Fatality Rate Fatalities Fatality Rate Source Smrm Dale Alaska u lac Hawall 0 Puerto Rica 7 5 Source smmi Data Y o e iui eveiy ueaui Second most fatal after oods Lightning Safety Summary Sizzlingsound orhairstanding Earth S fair weather eld up indicates a strong field 7 positive ionosphere negative surrate 5 5 gap bethen ash and e Maintained ov thunderstorms againstdischarge ovrair weather current thunder implies a 1 m range Thunderstorm electrification 3060 rule conservative 7 positive charge on cloud droplets 8 ice crvslals 7 Negative charge on telling hvdromel 305 lag 9 e mi range 7 lrldttctlve tharge transrer i charge on bottom or large hvdromelors tarried aw v u W3 30 m39quot e interrate tharge transrer Potentlal dlh ererlce between water 8 ice or diherent kinds orite Lightning ash 7 initial stepped leader rrorn cloud to ground a e r a building with plumbing and wiring Return stroke39 the sub querlt dart leaders and returrl strokes Not undertrees Fl sh mavbe onto marlv Sr k 39 Assume a 390 Enrich With onlv POSIlIVe strokes from anvtl amp bolts om the blue feet in contact wtth the ground most lightning occurs on Gueroast lit in Flor da tightning kills 75 people in the us approximately a people are injured tor each death Second weather killer arter rloods Avoid holding elongated metal ooleots like rifles or golf clubs 412008 FOR NEXT TIME Read Chapter 21 Downbursts
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