장음표시 사용
302쪽
32 F. L. ΕΚΜΑΝ, that the sal under-curroni in the alti dos uot fio constanti but is fits also the proximit to the surtace, hicli the ocean-Water attaina in the kagerach, is difforon a disserent times. hos disturbances areassuredi no meret accidental, ut ala os a regula an periodi ch racter. he must in the first place bo dopendon o tho different supplyos river-water in different semona in proportio a the outfloWing
sul, and the changes os salines a different opilis more sudden. he offect of th variatio of the rivor o the watem leve must hoWeVerin these reat basin bo sto an easti compensate by the more rapi offect of the indu In the summer-time esteri Wind prevat in the hagorach, hicli in a certain degre dam poli su ace- current et eo the wedis and omogian coasis. ut is the wateris damme u in in Shagorach, it must also ris in tho Baltic, and throughout the whole system os basin tho hichnes os the superficialhesher stratum is then incremed. he under-current an unde thesecircumstances e diminished even though the suppi os river-Water e increased, and by diffusion and ther cause tho different strata os Water Will o more an moris mixed But in prin easteri Wind are more prevalent, hereb the passage of the ursaco-stream ut os the hagorae is facilitated B this tho hydrostatio surptus-pressure of the superficia stratum is aised throughout the whol system os basins tholaesher ater o a ut more eaail and the under-current accordinHyma assume a livelle motion At his time os the oa the sursace both in tho Ballio an in tho attegat iacio est, and the oceani Water in Shagorac is the found neare the sursace than at ther times, a circumstance, hic atready in 1870 I xplaine a causod by the winda. Furthermore the ourse of the atroama at an time os the ear, may bo modified by variation os atmospheric pressure an by tormS. Simpl by Variation os atmosphori pressure, hicli disturbs the ordero the hydrosiati pressuros down to tho bottom, the directio os thεstream may, Without the cause ein easti discovered, be reversed, and the dolabi stream exchange sor single. Suppos sor instanc that ovo the whole of tho Balti the barometor inhs 30 this must avo in fame effect on the differetices os pressure o the two sideam a Vesetica sectio os the ound ascis the water in tho attegat had riae 4 centimhi res Stream Would then unde circumstances se in trouo the Sound both noli sursaco an a the otiom. Again is, suppos the Wate strata to have assume thei norma position, a that differen cenis ape-
303쪽
cificosight aro balance is differences os levet, an in unde current into tho Ballio rivs Only by the reactio of tho ouinomin au ace- current, the occurrenc os a great sal os tho baromotor ovo tho orth-Sea, or aurea rise Ver the altic, tot cause tho unde current in the ound o bo revorso in consequenc os tho hydrostati pressure intho Ballio sing incro e down to the ouom. number os complic te casea re here possibio, sor example lasti amon othors that is arisin os ibo attegat in consoquoncs os in offect of tho in in tho North-Sea, ins attegat jus arrivo at tho levo o tho Balti and thobottom-Wator streamo into in Baltic es in consequenco os ita greater specific gravit '). by Reaetion- Stream arising rom vaporation. When the water in an ocean-basin evaporates more rapidi stanthe res Water rom tho surrounding Vers an compensate, it levet must o lowere relativel to that of the ocean in equilibrium bet sonthes Walsr-districis is thus disturbe down to tho otio and thoocean's wator flows in The litile additions os hydrostati pressure, whicli ho wator in tho firs name localit experiences in consequencis of the sal rema ining there, graduali coalesce, an it is clea that, is the water ere no changed the ictor ater-colum bot eo thobotioni and tho ursace at tho basin's mout might o a las balanoodis in io vor ono bove the leve os that depi a the opposite extremit os tho basin. he differetice os pressure in the lower strata ould thus o neutraligod, ut ecauso the inclination os tho ursaco stilliss- mains, a stream scies depin Would constanti flo to tho vaporatinglocati . ut a soon a this state os tangs too place or then at
should bo the consoquetice of the disserenc os pressure botweon tho tWowater-regiona, and by the abasementis levet, hic is cauus at tho mouin by the stream reaction, the equilibrium there again is disturbo domi tho ouom. B this an undercurrent inses, hich naturali mill bo
' Tho account I have inve os the stream in these basins, is parti Dundedoni o theoretical rounda me ma homeVer oon expecto more complete experimenta investigatio of these Walers carried ut at the expense of the wedia go-
304쪽
34 F. L. ΚMAΝ sodorom in ovaporatin basin iiseis, thii discharin a quantity os mater correspondin to the surptus carrie thiste by the sursace-stream. This undercurrent penetrate trough the asina mout into in oceanand there sinis in consequenco oscit groator sight. Provido the dimensions of the mout assor sussicioni room for his oubio circulation, in spocssic eight os the wator in the basin an probabi not attain suo an amount, that a rea surptus os hydrostati pressuro hould talis placo rom that fido, ero it no holpo by tho excos os Wales carried thitho by mechanica reaction. Τhis appears to me lihely to e tho trus explanation os thedoubis troam in tho trait o Gibrattar. ho thoo , hic attempta toaccount for the under-current excluatvel by the greater specific gravi os tho editerranean's ater, is besides destituto os the necossa Moundationi a long a Wo no nothin about tho relativo sight os thelevets. he hie dissorsnce etwosii tho curronis of Gibraltar and the Sound appears to me to e that in the rs caue the ursace-current flows homo localit Wit constant love to one, here the leve is al-ways inhing, hereas in the secon casse it flows rom a region, hereth lovo is alWays rising to one, here it is constant. In furtho confirmation os this vis I may be allowe to adduco an experiment, hicli I made to convince myseis that a doubi stream
os his in may bs produce independenti os tho specific Wolotis the
the partition a constant under-stream as observe to o hom tho division os in box hom hic tho ater escaped, to that into hic it Was admitted. his stream a then analogous to that, hic existabet eo the editorranean and the ocean, illi meret in disseretice, that in his aso the water flowed instoad os vaporating homine su
305쪽
Bosors vittin the question os in reaction-strema, I be to recapitulat parti the result os his specia research, an to examine Dommy oin os te some circumstances, hic may be os importanos insormin a clear notion os the ocean-current properties an movementa. Is a fro ocean-current e supposed to OV unde suci circumstances that the los of Vis viva, hic it suffers hom tho resistanc os frictio at very oint of it courae e lWays compensate hom Bomo conatanti active ource, the mas of Water, hich the stream carris is in a uni os time, ould continuali increase so the stream velocitythen decreases mors lowl than iis mas incremes pag. 18). Although mio notor to calculato the influenco on the velocit os an oceani atream, arising rom the conversion os a pari os ita vis viva intoheat, neveriheles it seem probabie, that in state os in caso not
the mas os tho morin mater Will e considerabi enlarge by tho me- canica reactio of the stream o the eighbou in mater-strata, an ingonora I hin Ws may say that esset Gion o lighter alter o the Oceanproduce much more powersu an more laintis currenta, than fiat romtheir original, a me ould have evected. - his circumstanc has without doub boon to much overtook6d thus e. g. - ΜΑURY, hensrom in sectio an velocit os in Gul stream a tho Florida passage, compare Wit thos a Cape aster o endomoum to calculato tho inclination os ita unde auriace ).
306쪽
Ι an ocean-stream move formar in a mas os Wator, ither atres o havm a lower motion in tho fame or an other direction, homas of the forme mill uriniit progress continuali increme, talethat os in latior diminishes for the more rapi aeream ill communicaseus istion to the waler-molectile of the alter Henco ariae the aha finition os the streams, apparent even in the res ocean, hic has sooston se an objectis monde to travollers. ho mixture os the watoreos the difforon susams, hic is formo a the placo os contact, is in fac carrie o in tho more rapi stroam in hicli is it absorbed. In
mos cases in more rapi stream is a sursace-current oscii ter ater. Τlis ater oscit, that mixes Wit the surroundinchoavior ater, does nottherosor continue t run a an intermediate stratum be-een the streams,
lightor than the lows stream's ater. he inhin mixture is replacedis the water, oming Domino iddie toward in fides os the stream, and thus arises Within the constanti advancin stream an inne circulation in tho place os ita section. y this inno circulatio an on ine holo perpetuat, though ver leus an les marhed dissereno is maintained si es this stream and the mors lowl flowinchoavier ater, tho propertis os hic remat almos unchangod sor, though it paris With some of iis ator, i receives nono. his circulation, hichris also roinforco by the difference os proasuro et es tho tW atreams, Salso probabi the cause of the tendency, hic hos ocean-current se. g. in Guliatreem display, o pii longitudinali into ne streamS. In Ome places, a Q. g. long tho Wodis coast os in Sh gerach, it appens that s Wo streams, running eside achother, that Mith tho savior ater is tho more rapid. In theso casea in circulatio jus describe t ea notho courso, in that tho mixtur os lighter mater, hich the earier current continuali acquires, flows pWard. Itinen appens, stat sor a moderato in tho undulationa ill e more laebis oti hos paris os the hsavior stream, hicli are contiguous to thelioter ater sor ne masses os mater, hitherio unaffected by the Wiud, ars ther constanti risin to the surtace. Suriaco-current oscii ter ater havs a tendeno to diffuso them-selves, parti in consequence of the no mater that the acquire, Salso in consequence of the reater lateria pressure duo to thoi higherlovol this ill e tho grsator tho lighter the water is in comparison in that round an ocean-current os Warm ut ait ater, such a the
307쪽
havs in the preceedin pages endeavo edis sar a possibi toillustrato sparatot sach of the difforent causes, hich ive is to
ocean-currenta, as et a the Various ind of stream thus originating. But it is solRovident, that the Ocean-currenis, such a the in nature present themselves, must, both a regard thei force and thei courso,as determine by many or ali os theae causes contemporaneously, and thiathe more so the more extensive the current are. he origina prime-moVers, eat, Vaporation, aintai and Wind, ac in realit wit vo difforent average foro an in a very different anne in different puris of the current' course, to a nothin os thei Variation it Aeasons os the ear etc., and of the irregularit os the ind and atmospheri pros- auro; his obtians speciali a regard the oceani Sursace-currenis, hichin their long courso are expose to ad the vas differences os motoorologica circumstances, hicli ake place o the sursace of the arth. Ever stream uiside in region in hich iis riving-force is spociallyactivo, must associale tuet With ome ther movement os the ocean, an iis courso it therofore e materiali influhnced by the circumstances, hic render Such a combination illi thor stream possibio. horeaction-currentS, hic it causes may again ive is to ther similaratreams, an beside the reaction-stream can ometimes affect both thosor an directio of the origina current, hic is moreoVer Ο SSentiali influenco by the contour os the bottom and the hores. Dj0jtjgod by
308쪽
38 F. L. ΕΚΜΑΝ,Εven i hydrodynamica science ero sussicienti develope totroat this complicato problem, it ould in the uiset e toppe is Want os a competent od o observations. Although thorofore therocis
but flendor prospectis science eing Eoo in a condition suli to com- prohon ali ho cause of the vas current-motion in the ope ocean, We ma neVeriheles see to approximate to that interestin subjec os human reuearch, in ordo i possibi a least o discover, What circumstancos must in the rs placo e investigate in ordo that the question a receive it prope solution.
V e set ut rom the principio that illi exception solis
are originali produce by disserenuos os lovol, an is it o surtho admittod that it is tho nequa distribution os heat, evaporatio an rain- fiat, hicli chiefl oves ris to theso dissorencos, it would seem dosirable in the firs placeo inquire, o much the leve os the se in a certain
region a b altero in a uni os time by ac os these causes, suppositi no motio sor the momen to talio place. ΑΗ regard the rst, vig the changes of leve caused by eat, thereis only one Way o determining them, amet is calculatin the absoluto quantit os eat, hicli the ea Mihin a ive region acquires ortosos iu a ivon time; hom in increas cir decreave os Warnithothus obivino as a result, the change os leve must orasduced. ΑΗ regardatho possibilit os suc a calculation, e ma in the present state os
309쪽
is there et he when the vaporatu Vapoli is condensed is again inpari communicato to the ea by the indου, or is ne preser o a So, serves to reduce the os of hea caused by evaporation. In consequence of the rapi changes of tho atmospherio stratu Ver the ocean- surtaco the quantit os armili, thus tarde by the inds, ought notto b dostituto os Got. In ther region again the sursace of the eama homo analogous cause suffer a los of heat Lastly the convorsion os motion into eat has in various way an effect o the ea. Thestreams, that circulate there are continuali resiste in thei motion byresistanc os many indΗ. hia tho holo os the Ver considerabio foroe, require t ov0r-come this resistance, is convertet into arm th, as also on the ther an every aindrop that talis pon the ursac0, must there et re a certain amount of heat, hen iis fallin volocityis toppod. he vis viva, hicli the Wind contain, et the ocean into
quenc os his motion, a certain amount os heat, hicli the ocean has acquired, utiles it hould meret have serve to compensato the os of hea through vaporation. Again to stermino the depres/ion os leve caused by evaporation, method are vallabie eitheroo endeat ou to determine it is direct observation, oro calculato it rom meteorologica observations of the locality, viri με fuit Moertaine the law of evaporation. he rs proces hasbeon Hed, ut the observation are, it is nown, o fe an conducted in suo a manner, that the important question os vaporation rom the
310쪽
sis of the eat an light of the fures, there must ad sali throughout thewhol os the torrid one o an verage 75.D' Elo-uniis os eat nevery quare decimhtre os sursace Let iis suppos that his quantit os hsat, deducting only one laurili sor atmospheri absorption, i. e. 56.5 Hlo-unit o the quare decimhtre, is aheno by tho se mater, and that in quantit os heat contemporaneousi communicats to the Arcticinousis AE; o have thus, it respecto the quantit os hsat absorbed, placo tho calculation in Mootin sar o favo abis to the forme region. h los os hea through vaporation an radiatio must scim-monsol greator in tho orri than in the retio gone. ut lotis suppos them equat, or in ther ords, ah no account os these losses os hoat in calculatin the dissereno es levet et eo the wo gones hichtho phoenomen os sat ould produce. e ma in his case e auro, that ws halliso find the difforonc os levet, caused by heat, o litile, ovon though, should neglect the influence, hic the atmosphore may
have o the sea' temperature, as also that arising rom the conversionos motion into eat a regarda his laiter e have moreoVeros et noreason to suppose, that an greater disserenos os temperature etwoen
difforon rogions os the ocean ovi bo causod by t. ho maximum dissoronos os levet, hic the effect os temporaturo could produco in ada botmeon the sea-sursace in the orti an in Arcti gonos, eshould thorosore finda calculatin tho dilatatio ostilis ater, hicli an accossion os 56.5 hilo-uniis of heat on very quar decimhtro os hosursaco ould produce. Is o sor his purpos calculato tho dilatationos a colum os Wate 56. decimhtres igh, hen the temperatur is ai- sod rom 24' Contg. to 25', e mahe in calculation in a manno toosavourable to the reatnes os the dilatation. ut tho dilatation is novertheles oni 1 i. millimhtres. Howevo imperiaci the observations of Vaporation may be, ema nevortheles With certaint assume that he hange os levet, produco by it in a V ithin the oui gone is considerabi moro han