APRIL, 1914. MONTHLY WEATHER REWW. 223 of no direct consequence to lants, its importance being ordinary weather stations. Therefore it would be of urely meteorological, the reP ative huniiclit affects them great advantage to students of plant life if such deter- Zirectly, since it so largely determines t i! e amount of minations could be made at agricultural and forest exper- transpiration. The monthly , mean relative humidity iment stations.' and its minimum, and particularly the average relative Sunshine. humidity with its minimum during periods of different wind direction, are things important to know. In local- Light is another important factor in t-he development ities with a humid climate and wit,hout n, distinct hot of plants. The amount avdable for plants in a given eriod, where fogs are frequent, observations upon the 1oc.alit-y depends upon cloudiness and geographic lati- fatter should, of course, Gve all the information as to tude. For this reason, the avera. e monthly cloudi- humidit of the air necessary for the purposes of botanical ness, tjhe average cloudiness for win as of different direc- geograpE y.a tions, and the number of clear, semicloudy, and cloudy Precipitation. days should be computed. Some simple sunshine record, especially for winds of different directions, is The important part which precipitation, especially also necessary. The occurrence of days with sunshine total precipitation, plays in plant life, needs no discussion. should be given in per cent of the total number of obser- The maximum precipitation for any day during the month va tions. and the number of da s of precipitation are also inipor- Bammetric pressure. tant. Since among $e latter, however, are included days mth only traces of recipitation, the result,ing data Air pressure has no direct bearing upon plant life, does not give an idea of tier intensity of the precipitation escept that its observation often makes it possible to or its frequency. For this reason it will be wcll to coni- forecast changes of importance to agriculture. pute the number of days with considerable precipitat,ion in per cent of the total number of days of observat,ion in eneral, as well as specifically, for winds of different CONCLUSION. iirection. In conclusion, I wish to reiterate what I said at the Snow CO'L'ET. beginning, nnmely, that, with the exception of the records of soil humidity and soil tem erature, tho sys- Snow cover, of course, also has an import,ant effect tem of nieteorological observations I K ave outlined can upon plant activity. Both the number of days with be carried out with the data which are regularly ob- snow on the ground and the depth of the cover should be tained by ovr weather stations. The chan e from recorded. Since the de th of the snow varies with the present practice to the system I have descri% ed will topography, its de th sK ould be measured at cliffwent entail, therefore, merely a different use of present data places. In the vaIp ey the snow stakes should be plnccd, rather than a radical change in the plan of collection. If practical in an open field and in awood lot; in the nioun- The aid to botanical geography which such a chan e tams on a ievel place and on two moderate slopes of the would give would far more than compensate, I thina , revailing directions. For each iiion bh tohe average for any inconvenience or added effort that it might gepth of the snow cover should represent only t.hose bring about. days when snow was actually on t,he ground. In order .. to determine the effect of local topographic conditions, it would bo well to note the averages separntcly for each TASKS AND PROBLEXS hR XETEOROLOGCICAL EX- snow stake. Data on the maximum and minimum of PLORATIONS IN THE ANTARCTIC. snow cover for each month are also essential, and it is By Prof. Dr. WILEELM MEINARDUB, bffiinster, WeEtphalis. very useful to have the de th of the snow separately for every 10 days (decade). uch detailed iilfornitrtion con- [Trsnslated by Cleveland Abbe, r from Geogra hische Zeitachrift, Leipzig, 1914. SO. l Jki., 1. HIt, p. h-34.) cermng the snow cover is especially instructive at the time of its appearance and disappearance. Since it No other region on the earth has witnessed durin comes and oes in different years and in different local- the past decade, such advances in our knowledge ities at dif erent times, however? this average depth its meteorological conditions as has that within the should be given for all 36 decades. higher southern latitudes. As Hanii was closing the second edition of his Handbook of Climatolo Soil moisture. he was practic.ally limited in material for of the Antarctic %one, to that collected in its seas 50 to In ?regions it is necessar for pur oses of botanical GO years previously by Sir James Ross. There was no eograp y to have a more ietailed R-nowledge of the -- I Here a in the adoption of a standard apparatus seems the only means oIobtaini?g %umidity of the soil than would ordinarily be indicnt.ed desirable tafor large areas and for different regions. The great diffmnw In soils in by the amount of rainfall and snowfall. In such places different localities and the great dlfflculty in any one locality of obtaining consecutive samples oIsoil whlch are physically alike, malies It necessarv that any ap aratus designed periodic and systematic determinations of soil humidity for consistent soil-moisture determinations shall involve the plan of akvsmeasuring the same body of soil. The electrical resistance apparatus is good in this'respect but, giving due consideration to local topographic and soil unfortunately, Is no! always rellable from a mechanical standpoint. A comparatlively conditions are important. Unfortunately, such cleter- simple piece 01 equipment h,as been suggested b C. G. Bates of the Fremont Fore+ experiment station. This is a porous cup wh&h would contain the sample of soil minations are not only .time consuming, but. require a whose moisture wfq to be determined periodically. This porous cup would flt cl&y Inside 3 second similar cup which would, in turn, be located at the bqttom of a brass eat deal of 'udgnient in the selectmionof soil samples. tube at any desired depth,helow the surhce 01 the ground. To the soil cup would be Fhe amount o moisture in the soil depends upon t,he lat- attached a cord or rod which would extend u through the brass tube. -4t the top of 1 the tube would be a firmly built platform on wgich could be placed asufaclently delicate ter's physical properties, ita method of cultivation, and balance for weighing the soil cup. Wheh weighing was desired the cu would be raised sufficiently to clear the exterior cup. attached to the beam of the Balance and then so on, and can not be determined accurately at tho replaced. The contenk 01 the cup might be a sample 01 the local soil, a standard sand or soil of certain ph sic51 and mechanical properties, or a standard salt wlth 8plJght The CrdOpUon by all weather stations andpbsewers oIa standard evaporometer would avidity lor water. 6nder eitber lon the moisture of the entents (by absorption Or in large mea.solve the uestlon 01humidity and wmd-movementrecords and would expulsion throqh the porous waky would alwap bear a cartam relation to the m0lStUre lurnlph dab directly usable%y the plant bl olog1~t.9. 01 the surroundmg soil. !

Unauthenticated | Downloaded 10/01/21 04:29 PM UTC 224 MONTHLY WEATHER REVIEW. ~IL,1914 information available for the hti~rC.ticniaiulancl, whose tained. These stations were located as shown in Table 1 areal estent is one and n hdf times that of Europe. and the map, figure 1. Indeed, but 15 years ago Antarctica had not yet one TABLEl.-iMctcoroloyicaieal stations in Awtnrcticn owzipied for one or more single meteorologicd station, so that Hitnil closed his yrars. work with die words: "Eine, oder iiocli besver mehrere Uberwin terungeii in hohen siidlichen Breiten wiirden Station. Nationality. Lat. Long. Periods. eiiiige der wichtigsten uncl in teressantes ten Probleme ___.___ _- der wisscaschaftlicheii Klimatologie zu loaeii imst;iii de scin. Die Kenn tnis der IViu tertempcratur ini Palm 440 39' w. 1903-1914 (P). aebiet eiiier Wasserheniisphare ist gegenwart.ig das 570 00' w. 1W)W. 8ringendste Erfordernis unserer Wisseilachaft." 63O 4YW. 1904-5. The desire of our greatest clinintologist that there niight 63" 54' w. 1909. be oiie or more winter-long es .)editions to the Antarctic, there voiced, was soon to be iulfilled. The first winter- Cape Adare.. .. ._. .. ._. ..I Norwegian.. 170° 08' E. 1898-1Bo. Gauss Station.. __ .. .. German.. .. . SV 38' E. 19023. ing was in 159s-99 in the setis west of Griiliaai Land, by YacMurdo Sound.. -.._./ English.. ... 1w)" 30'. E. 1902-1904.1~, tlie Belgian expedition under De Gerlache in tlie Heir:qi.cn. 1913-13.1911-1913. lWo 30' W. It was not granted this expedition to est:tblish n 1:111d 140° 00' E. 1912-1914 (t). shtion; caught in the floes tlie ship wits crinipellcrl t,o drift along aii unknown :incl unseen stretch of the Ant- arctic coast. Borcharevink's expedition to Ross Sea was the first to estahish ?-liid nininta.iii n ldstutio?i. It was located at Cape Aclnre for almost a year 111 1599-1900. These two especlitions were the nclvance guard of ft new epoch in Aiitnrctic esp1or:~tion w-liic'h began with the new century. It is still fresh iil the nieniory txnd its latest victories, the esteiision of our horizon t.o the South Pole itself by Amuiiclsen mid Scott., still thrill u5. I niny then )ass over tlie viirious sttlges of this litt.est ac tivity in esjioratim. Germans, Freiicli , Englisli, Scotch, Norwepinus, Swdes, Argcn tiit ittiis, Austr;ilinus, till linvc had :I pirt SO t1ia.t this fielil of explorstion is niore truly iiitemntionnl in chtxmc t.er than ally other on the globc. Here tlie f:inie of success beckons not merely to the anil)it.ious es hrer, but morc nlluringly to the investigator who woulct sink himself in study of the peculiar nature of a lonely, sea-surrouiitleil icy continent never yet even brushed by any form of humnn culture. It is my purpose to communicate some of the meteoro- logical results which may be based upon the observa- tional material collected b the dntarctic expeditions of the past decennium, as we1 r as to review the still unsolved problems which must spur us onward to further explor& tion in Antarctica.

CHARACTER OF PREVIOUS METEOROLOGICAL OBSERVA- FIO.1.-Location of meteorologicalstationv within the south polar reglons. TIONS. Some of the stations listed have had branch stations We may begin by considering the character of revious in their vicinities for longer or shorter periods, e. g., on collections of meteorological observations in our Keld and tlie Gnusuberg, on Mount Erebus, etc. their evaluation. (See the map, fig. 1.) Tli~sit appears thnt so far the fringe only of the Ant- Observations have been ninde nt maiiilancl stations, arctic continent has been occupied by fixed stations, of on sled journeys, on drifting floes, and recently also by which tlie southernmost is Aniundsen's "Frainheim " hi means of kit,es aiicl balloons. lat. 75' 3s' S., or about 1,300 km. froin the South Pole; Fid land station.s.--ln studying the ntmosphere, sta- S litzbergen lilts a corresponding location on the Northern tions at fixed points are of t,he moat value, because the $em is plier e. esternal conclit,ions of the surroundings reniaiii the same. Sled jou.r.n.cya.--aiiotlier kind of materid is secured on Such observations, when continued through one or more the olar sled jouriieys, which usually have one of these years, can be used t,o determine seasonal c.ontrasts and to fisccF stmationsas their starting point. In the nature of ascertain averages that apply to the surroundings of the things these observations can be but scattered samples of station. Such stations hare tlie further advantage that t.he atmospheric conditions along t'lieir routes. Because of, they can be revisited by other expeditions, so that one the almost continuous change of place the indivitlurrl may secure comparable dah for various years. observations can not be summarized and given general So far eight localities within the true south polar region application. In general, all the elements observed vary have been occupied as meteorological statmiomof some wit,li each locality, so that in utilizing meteorological duration and one of them, Adelie Land, is still main- observations made on sled journeys one must always bear in mind that the weather then encountered may depart 1 See also Ham's &Y ositlon in hk Handhuch d. Glhtologie, 3d ed. Stuttprt, 1911, V. 3, p. 67749!3.-W. & more or less widely from the average conditions or climate

Unauthenticated | Downloaded 10/01/21 04:29 PM UTC ~IL,1914. MONTHLY WEATHER REVIEW. 225 of the region. This fact has not always been considered, NEEDS IN FUTURE EXPLORATION. and the resultin hasty conclusions may readily be under- mined b later o% servations. Furthermore, sled journeys In general, it is clear from the foregoing that future am usua7 ly undertaken during the polar daylight, so their expeditions to the Antnrctic will best further the study observational material is applicable only to a certain sea- of it,s cliiii t 1 ry if they establish long-lived fiseil sta- son of the year. However, sled journeys can furnish t.ions which shaOoP 1 11e locitterl as fair inland as possible. It information of general value concerning the climate of seeins tliiit the estwhlishiieot.of subsidinrg stations is ELISO the regions traversed by recording the depth of the snow very useful, since they aid in deterniining the extent of and the ice covers, the orientation of the snow dunes, phe- local conditions. Of coui-se such espeditions will also nomena of melting, and such features. In this way t,liey urraiige for simult,mieous kite ttiitl balloon flights. We are always very important aids to our knowledge in c.ase may well hope that the iiioderii and future development other means fail. of aeronautics will also contribute to the esploration of Sled journeys of major significance have been liniitecl the South Polar regions. to the eastern ortion of Antarctica. The trips in Vic- toria Land ma(P e by the English espeilitions seeking t.he BIETEOROLOGICAL CONDITIONS AND PROBLEMS OF ANT- magnetic South Yole are specidly iiotewortliy Wc: ARCTICA. would not omit to niention thc >ole~vartltrips i1.ssoci:tte.d Previous observations on the atniospheiic conditions with the names of Scott, ShackI eton, nnd Aniuiidscn. of t.lw hitar& continciit have revealed many unex- Floe-drift journe7js.-A third clnss of observ:itions re- pa; tecl pro\Jleiiis. Foremost among these is the element sult from expeditions compelled t.0 drift in the ice floes. "Temperature " which directly or indirectly sets its The usefulness of such material is intermediate between st.anip upon the country. that of the ked stations nntl that from sled journeys. The floedrift and the fired station agreo in that tlie sur- jrummr ttmpuuturs, roundings do not niaterinlly change during t.lis pcrioil of occupation, for the observation is always at the ship The low siininier temperature is the most im ortant and the surroundin s are always snow mid ice. Chi t.he cli:trttct.eristic 01"the Poutli polar temperature cl1i)Ytribu- The arerage temperuturc of the wnrnieat month, other hand the grnc4 ual shifting as the floe moves is sini- t,ioii. ilar to that of the changing slcdding camps, altliou~ht.lic Decenilm or Jniiutwy, is below 0" C. almost exei where former is very slow, while in the latter ciwe rupiil changcs nlong the borders of t,he Antarctic. iiininlancl. T1 e only are specially emphasized. ,4ccorilingly the floe-drift ob- exce\)tion to t,liis is the west coast of Grahuni Land, where 24 n servations acquire more or less significance RS the dura- the rcnch cspctlition founi! mean January teniperat,ure tion and direction of the drift journey varies. (Jf 1' C'. in latitude 65" 8.; aiiil this is offset by 8 mean The essentially fioe-drift espeilitions t,o the .Snt.arctic Jnnunry t mpernture of only - 0.0"C!., found by the Swecl- include the Bdgicn expedition west of Gralinni Imid ish expedition on the east coast of the same lnncl in lati- in 1898-99, the Scotia es edition of 1903-1904, :uid the tude 64" 30' S. If one coniputes the average January German Antarctic. expe&ion of 1012 iii Wetldell Sea. tenipsratures for the latitutlc circles it appears that the Besides these a larae iiuniber of other espeditions liuve isotlicrni for 0" C. aliiiost coinci(1es wit.h the $ntarctic been compelled to Rift sometimes for nioiitli;,c: as wts the Circle (lnt. GGO 30' S.). The region bound by this curve lot of the German South Polar Especlitioii froiii t1l.c be- has itii nreal cxtmt of 21,000,000 square kilometers, more of February to the beginning of April, 190?, uft.er than tlouhle the extent of Euroie [or of Australin, and kinninfit had eft its winter uarteis. about lwlf tlirtt of the Americas]. In spite of its faror- Kite and ba.Zbon o1 semations.--Finally (miic t.he en- nl)lc s~iniiiic~insolation [perihelion suiiimer], this ssten- deavors to learn the nature of the liiglier atniospheric. sivc region st.antls under the sign of Jack Frost. strata by means of kites ant1 balloons. Here also t,lic re- The Xorth Polar regions have far niore favorable con- sults are mostly in the nature of isolated s:tmples of the dit,ions. Nohn's discussion of the observations by Nan- meteorologic, conditions : and Again it, iiiust he borne in sen's espeditioii in the Fmn. indicates a July temperature mind that the observations are clcteimincA l,y tlic nio- lwhv U" c'. prevailing over a limited area (SO0,OOO square mentary weather conditions, so t,lint. they do lint sul-lice kilometers), w;tllin the latitude of 55" N. Thus in the for eneral averages unless they can 1)o rcp'at,t!tl (lady warniest: niont.li the isotherm of 0" lies but 450 kilometers at t f e same locality. Great ciwe must! 1Jc u:ml in hsiiy froin t.he 1)olc in the nort,li, while in the south it has an general c.onclusions upon such materid. However, t,lns :~vcriige ilist :mce of 2.GOO ki1oniet.eI-s from the COP m no way detracts from these up Ier-nir observntions aince-,' rcspondiii~point. they are of the greatest signiH caiice to studics of t.hr But the summer teinperatures of the southe.rn polar momentary conditiolis and of weather secjncncc. regions are not merely close to freezing; the farther pole- w:ird one Certainlv one of the greatest triumphs of tlie C'1 ~l'll1811 goes the farther sinlis the summer temperature South Pore Expedition was Dr. Enrkow's ? succtvjsful below 0" C!., in spite of the more favorable insolation carrying out of 255 ascensions on 309 Il:i~-scluriiig tile conditions. So that Aniundseii found the average teni- floe-drift journey in Weddell Sen. d >rrliniint~ryc.cn- pernture of the warmest month (December) at Framheim ilnt. 75" S.? alt. close to sea level) to be but -6.2'. pu tation indicates that the lliglicst. f> :dlo 01 1 sou 1 i( 1ing 35' reached an alt,itude of 17,,200 1iiet.ei.s [56,4:;(! ftvt., or 10.7 This is a fact difficult of esplanation, since the insolation miles]. These se.ries of flights furnish tlir first note- nt this high southern latitude continues uninterruptedly worthy data bearing on the upper-air conditions ovw t.lie day and night through the sumnier months escept as it Antarctic regions, ani1 we may well look fonvml'c1 espw t- may Le decreased by t,he rather slight cloudiness. The ant1 to the general conclusioiis which this first pio~wer sled journeys toward the South Pole also show altogether worz shall warrant. 'IJnder other circi.iuist:uicc.s ant: uiiusual low temperatures for the sumnier season in which must rely upon cloud observations for iiiforniat,ion 1)t::Lr- they were made. A midsummer temperature of -50' mg upon up er air conditions, and numerous contiaibu- C. (- 5s" F.) is not to be readily esplamed even though tiom of this Li have already been macle. the district about the South Pole iaelf does lie at an ~ altitude of over 3,000 nieters [i. e., over 9,840 feet]. Barkow,, VorUuftgw Berlcht fiber die nieteorologischcn Beohachtuwn auf der One of the principal problems for future espeditions &o* &tsrkthhe.n Exped'ition. Vdentl. Preuss. meteorol. ImtitUt. Ber- lin, 1918. will be to find the esplanation of this low summer tan- Unauthenticated | Downloaded 10/01/21 04:29 PM UTC 226 MONTHLP WEATHER REVJXW. APRLL, 1914 perature at high southern latitudes. It may be espected trary the east winds met with in the marginal region of that future upper-air investigations will aid in the solu- the westerly winds are not d and cold but moist warm, tion. and snow-producin . Dvgxki's German South Polar Winier temperature. Expedition establis% ed ths point most clearly. As the Gauss sailed southward from Kerguelen in Febru Another heretofore unexplained phenomenon is the 1902, she was for a while in the zone of westerly wiz uniformity of the winter temperature durin April to but after crossing latitude 64O S. entered the region of September. The feature is most pronounce% in East easterly winds where she remained for over a year. Dur- Antarctica at the English station on MacMurdo Sound. ing this time the prevailing wind wa8 easterly and when- There the monthly temperatures remain between 54' ever these east winds showed marked increase in force and 27' C. from April to September. The annual tem- the weather became warm and moist with copious snow- perature curve seems to be flattened, quite in contrast to fall. Tobe sure the higher temperature of the east winds its course in the Northern Hemisphere where the tcm- night be explained by assunung they are of southern perature sinks rapidly until midwinter when it imme- origin and a fohn-like character; their higher humidity diately begins to nse again. Why is there no pronounced contradicted this view. The heavy precipitation char- Antarctic winter month whose low temperatures distin- acterizing these enst winds is yet more dlscordant with guish it sharply from its neighboring adjacent months 'd the fohn theory. Local temperature contrasts. If these easterly winds of the Gauss station are regarded as cyclonic in nature their warm, moist character is The local differences in temperature distribution over readily and adequately explained. In this case their the mar 'n of Antarctica will not be discussed here. It origin inust lie to tlie north, that is in the region of the must su Ece to say that the east and west sides of Graham southern Indian Ocean. This view also harmonizes with Land show im ortant differences, the west side being the observed subantarctic trough of low pressure which warmer than tfl e east side. This feature is serves as the path of the de ressions that march from west referable to the different wind conditions, an inmadyit niay to east about the South PoP ar regions. well be com ared with the differences prevailing between Of course in the barometric depressions of the Southern the west anB east coasts of Greenland. Hemisphere the air circulation is spirally clockwise. (See There is a surprising and unesplained difference be fig. 3.) Accordifigly the east winds on the south side of tween the observations at Fraiiiheim (Amundsen) and at these de ressions must have a northern on n. They are MacMurdo Sound (EngliFh). Although both localities conling' Prom warmer latitudes and from tf e ocean, and are in almost the same latitude, are at sea level, and sinii- their hgher temperature and humidity is a natural conse- larl located at the edge of the Ice Barrier, yet there is uence. The winter station of the Gauss was particularly a (9ifference of not less than 7.5" C!. between the two zivorable for the clear development of these features. annual means, Framheim being colder than Macllurdo No mountains, peninsulas, or other topographic features Sound. Further, Framheim shows the lowest mean annual could disturb the air currents. The even coast of Kaiser temperature (- 25.2' C., - 13.4" F., in lat. 78' 3s' S.) so Wilhelm I1 Land stretches from west to east and the far observed anywhere on the globe. The lowest average Gauss station was located 90 km. north of the coast. temperature observed durin the Frain's drift in the Arctic Ocean was -20.5' C. f-4.9' F.) for 1895 and an average latitude of 85" N. Some years ago the author computed the average annual temperature for the South Pole and found -25O C., a result which will probably be re arded as somewhat too high. %oes the cold pole of the Southern Hemisphere coin- cide with the south geogra hic pole? This problem awaits solution. Previous ot servations make it prob- able that the cold pole is located somewhat eccentrically, being shoved over toward the Indian Ocean, for the antarctic shores of the South Atlantic and South Indian Oceans are somewhat colder than those of the South Pacific. Pressure and winds. The more recent investigations show the sea-level pres- sures and winds of West Antarctica are about what theor would predict. Wind conditions indicate that a troug!r 1 or furrow of low pressure surrounds 6he south polar re- ons in latitudes 60' to $0' s.,and an increasin ressure fom those latitudes poleward. (See fig. 2.1 %e low- pressure trough or furrow? appropriately designated the subantarctic circumpolar barometric trough or furrow, is thus seen to act as an important. wind divide. Formerly it was believed that the enst winds south of the trough were blowing from tlie hi. h-pressure area sup- posed to cover the antarctic lands. #hese east winds mere osed to be of antarctic origin and to have the dry, FIG.Z.-Sketch of thc course of the Isobars at 888 level within the south olar reglons. The isobars are intentionallv unnumbered ewe t the curve for 7dmm whose character of winter land winds such as mieht blow psition ran be plotted with &me certainty by dolpast observations. T& draw- from an area of continental high ressure. Obs&vations ng 18 planned to present on1 the probable form of the isobars conaldering the observed ses-level winds. H- . Lgh -- ms9ure: .. L. low ~888ur~:- ar&. ~-avertwe wind in these regions have not supporteB this view. On the con- directiOn.

Unauthenticated | Downloaded 10/01/21 04:29 PM UTC APRIL, 1914. MONTHLY WEATHER REVIEW. 227 Most of the other Antarctic stations have had similar We also need further explanation of the unusual fre- experiences with the east winds. Thus the warmest of the extreme1 stormy, cold southwest wind winds were from the northeast and north at the Swedish recorquenT ed at the Snow Hii station. As was stated above station on the east side of Graham Land, and at the this wind indicates a re 'on of low pressure over Weddeli French stations on the west side of the same. The Sea, but it is striking tEl at the wind is dry and cold and Scotia had cyclonal northeast winds at the east side therefore can not be considered as of truly cyclonal char- of Weddell Sea. In and about Ross Sea the conditions are acter. We shall return to the consideration of this wind. more complicated. Here the mountains of VictoriaLand, modify the direction and the character of the air currents PTeeipitat.ion. which can not be so simply described. It must be as- sumed that the barometric trough which forms the divide Certainly the chief characteristic of the Antarctic pre- between the easterly and the westerly winds, bends south- cipitation is that it almost always takes the form of snow. ward in the re 'on of Ross Sea or that there is here tl ten- Rainfalls belong to the dency to deveff op an independent ressure nlininium. It why so little has been known then becomes clear (see fig. 2) wR y the southeast winds tation for, as is well known, were the warmer at tho English stations in the southern the wa.y of the measurement of portion of Ross Sea. in the polar regions which are The distribution of pressure ltnd winds over Weddell Sea show similar modifications. Mecking and Mossniann tind this region dominated by low pressure especially during the winter, so that southwest winds prevail along Wi.- A. the west side and northeast winds prevail dong the east side. The floe-drift observtitions on the ~eutschlarrt~in 1912 confirmed these msuniptions. The modern explorations have thus necessitated some modifications of the simple scheme of pressure and wind distribution to bring it into accord with the continental outline of Antarctica. The most important fact emer from these observations is that the easterly winds op? thL k continental margin must be regarded as members of the circulation about centers of low pressure passing north of Antarctica. The east winds to the south of the sub- Antarctic circum olar barometric trough are the neces- -\ sary corollaries oP the west winds to the north. A coni- parison of the weather observed at Kerguelen and at Gauss station shows this. The international meteorological coiiperation of 1901- FIG.3.4mlation 8;am belof a cyclone in the Southern Hemhphm. 1904, originated by the German Antarctic expedition, Previously fallen snow is whirled up by the wind and was able to follow the course of the weather in high even dunn fine, dry weather drifting snow can fiil the southern latitudes much more accurately than the ex e- gages with Eialls that have already been measured. Even dition could have done alone. Mecking and Meinardp us when actual new snow is falling it is blown from the gage have drawn up s no tic weather maps for the Southern and but a small part is measured. The.e are, indeed, Hemisphere soutZP of atitude 30°, whereon one may. trace devices for reducing such losses at the gage but they are the paths of the highs and lows across the seas surround- not adequate to remove the source of error. In general ing Antarctica. The study bas not yet been completed, it is safer to use staff gages set up at well-selected points but it is already possible to state that these charts con- so that uniform records may be secured for driftings of hnthe view whch regards the marginal east winds of various intensities. The readin of such staff gages cer- Antarctica as elements of c clonal systems. tainl yield more reliable resuY ts than those from the The mechanics of these depressions appear to be much simp9 e snow measurer, which is no other than a rain ga e. more com hated than we have heretofore been ready to For these reasons the previous measurements in tf e assume. It had been thought that in the broad zone of Antarctic are hardly sufficient to give an accurate idea of water uniting the oceans on the south the development its precipitation. l'herefore it may be stated that one of and movement of the pressure system would show simpler the most urgent needs is a device which is adapted to features than in the northern zone of our latitudes, where securing records, even during an Antarctic snowstorm, continents and seaalternate. But in the south, also, the that mll permit a somewhat reliable estimate of the relations are com lex; lows and highs undergo varying precipitation. modifications, an their movements do not show that 'The available measurements will scarcely bear discws- uniformity that thex expedition of 1901 expected to find ing; however, the following may be mentioned: When when it sailed for the south. the east winds on the margins of Antarctica have a A question still unanswered is as to the great constancy cyolonal character-i. e,, are bringing moisture from of the east winds. At the winter quarters of the Gauss these winds blew with a constancy almost e ualin that of the trades; rarely were they interrupted Ify cams or by wester1 winds. There is undoubtedly some relation between tz e simple character of the coast line and this depressions will bring precipitation. In constancy of the east winds, but their dependence upon German the heaviest occur with north- the advancing de ressions on the north leads us to expect east and east winds accom an in a Low over the Medi- a lower degree oP constancy in these winds. terranean to the south an8 a over Scandinavia or 4767!2-1-

Unauthenticated | Downloaded 10/01/21 04:29 PM UTC 2% MONTHLY WEATHER REVIEW. -L, 1914 inent feature of Antarctica, and it exerts the most far- reaching influence upon the climatolo 'cal henomena of all its surroundings. I have also stuPI: ied t e problem of the source of supply for the inland ice when work' up the results of the German South Polar Expedition.?er- init me to briefly resent my views thereon. It is a well-esta1 lished fact that there is a stead flow of ice from the unknown interior of Antarctica. dis ice sheet overflows the margin of Antarctica and presents an alniost unbroken line where it surrenders to the sea in the form of icebergs. of this ice can not lie along the continentd marginThe Or?? on y, it must also be located snowfalls of March farther poleward for there can be no doubt that the interior mainland also lies snow buried as does its ma in. Sled journeys into the interior and to the Pole prove 7t at northwestern Germany, are proofs of this process. It no even in these central portions of the Antarctic mainland doubt occurs also on the east coasts of Greenland and of the determining elements of the landscape are snow and North America. ice : nowhere appeared extensive snow-free areas. It is probable that similar conditions arise on the Now if the interior of Antarctica is covered with snow southern side of depressions moving along the margin of and ice and there is a discharge of the same to the mar- Antarctica. Ia this case northerly winds bring in ginal oceans, it follows that over Antarctica as a whole moisture from the ocean to the southern side of the Low, the recipitation exceeds the eva oration. Marginal ice and on the boundary between the Low and tho High disc rlarge could occur only in sucl a region. It further the moisture separates out in the form of snow. The follows that the excess of precipitution over eva oration snow measurements at the Gauss station indicate, in niy must be furnished by air currents nioving towa2 the in- opinion, that the preci itation there exceeds 800 mm. terior of Antarctica. The hydro-economics of Antarctica per year, a very heavy all for the low temperature pre- must be somewhat as follows: The marginally discharging vaillng there. On the Pwestern side of Graham Land, ice is exporting water from the south polar regions; this also, with prevailing northeast winds there occurs heavy water loss must be compensated by an excess of precipi- precipitation under similar conditions, the measured tation over ova oration; and the excess precipitation must annual fall at Port Charcot amountin to almost 400 mm. be made possiYJ le by a corresponding supply of water In this case the northeast winds come f mm the perennially vapor earned by winds into the interior. open and warm waters of Drake Straits, and there must If the water imported annually be designated by De be a correspondingly great transfer of moisture toward the exported water vapor by D,,, the recipitation by A( Antarctica. the Antarctic evaporation by VIand %e exported iae by On the other hand, the precipitation is evidently much E, then under constant climatic conditions the annual smaller in Weddell Sea and its western boundary. It is state of affairs must be expressed by the equation: true that the observations at Snow Hill station are not usable, for the reasons De-D.=lV- V- E. precipitation can not be west winds were How can this e uation be satisfied? This question can The D~tctsC(XZund only be answerel by considerin the air currents and the its floe-drift in distribution of pressye at leveg higher than the earth's measurement surface. Anturctic pressures. The general view is that the whole south olar region cipitation. is dominated by a region of high ressure. $his view is On the whole, then I would regard it as very probable based upon the existence of easterP y winds on the margin that those portions of the margin of Antarctica which art' of Antarctica and the observed southward increase of fanned by cyclonal easterly winds are regions of heavy pressure. We have already seen that the myof recipitation. On the other hand those portions which, Antarctica is not under snticyclonal but cyclona pres- Eke western Wcddell Sea and Ross Sea, are exposed to sure conditions. If there is an Antarctic anticyclone it southerly winds arere ions of liiht precipitation. Further can esist only in the iiiner portion of Antarctica (see fig. observations are neef ed before more detailed conclusions 3) ; and its esistence there is a difficulty in the way of ex- may be drawn. Heretofore we have had but ti general laining the necessarily assumed interior snow cover. knowledge of the annual period of the precipitation, the For air flows toward an anticyclone iu its upper layers, observations indicating that the summer precipitation is then descends as relative1 dry air, and below flows out- heavier than that of winter. ward in all directions. 6nder such circumstances, un- fortunately for tlie theory, precipitation cannot form in Source of the inland ice. sufficient quantities to outbalance the evaporation as ex- pressed in the above equation. On the other hand evap Such investigations into the distribution of the Ant- oration is greater than precipitation in anticyclonai areas; arctic precipitation are, of course of the greatest im- the air descending froni greater heights is dynamically ortance in one of the cardinal probsms of the Antarctic.: heated, becomes relative1 very dry, and as it flows out- khat +re the meteorological conditions which supply and ward takes up nioisture 9rom the earth's surface and re- maintain Antarc.tica's continental ice sheet, the '(Inlnnd moves it from the region of the anticyclone. In our case Ice" ? That cover of ice and snow forms the most prom- this known mechanism of the anticyclone would ne--

Unauthenticated | Downloaded 10/01/21 04:29 PM UTC bm~,1914. MONTHLY WEAITHER REVIEW. 229 sarily cause a dryin out and removal of snow cover in the In the up er layers, above 2,000 m. ,this arching is absent; interior of the soutE- polar regions. in place or it the isobars sag toward the vicinity of the pole This consideration induces me to revise the theory of in accord with the cyclonic distribution of the “polar an Antarctic anticyclone. A certain line of reasoning, whirl.” In the district of the anticyclone the air move- whioh I shall not repeat here, shows me that the hit- ment is prevailing easterly, but with southerly compo- arctic continent must have a very high mean elevation, nents; in the district of the cyclone it is weaterly,mth as much as 2,000f200 m. above sea level. Herein lies northerly components. the key to the phenomenon of Antarctica as a possible and In figure 5 the arrows show only the meridional com- cveii actual source of supply of the inland ice. For DOW ponents of the winds; in addition the shaded area shows draw the followmg conclusions: The Antarctic the region of easterl ‘winds. If there were no land masses so niuch discussed in the past, is a pressure itbout the South Po9 e (the vertically exaggerated pro& of peculiar to the lower atmospheric strata figure 5 is uite arbitrary) then we might assume easterly onIy, appearing with distinctness only in the sea-level winds wous il prevail over all the district of the anti- pressure distribution. On the other hand the low Ant- cyclone. The actual continent, however, arctic temperature must produce such a rapid vertical portion of the anticyclone and the easterP y wmds Onlyto ap- a decrease in pressure that above a certain level the Ant- pear; and the land rises even into the overlying cyclone arctic pressure must be lower and not higher than that of ail11 westerly minds. surrounding regions. Thus tlie sea-level anticyclone The boundary between the easterly and the westerly must be overlain by a cyclone, the so-called “ polnr wliirl” wind? (shaded and unshaded portions of the figure) as- in tlie general circulation of. the globe. (Src: the cliamc- cends from sea level nt latitude 65’s. to meet the land at teristic kobms at 4,000 xu. in fig. 4.) , ,different latitudes and altitudes, dependihg upon the local ‘.‘to oura h . Where the general surface rises rapid1 in refkk& &w latitudes, as at the right of fi e 5, t K ere is the least s ace for the easterly winds to Yevelop; this seenis to be t1 e case in East Antarctica and particula.rly in Wilkea and Victoria Lands. (See figs. 2 and 4.) Where the coast retreats poleward and the back country rises slowly, there’the revion of the easterly winds is more extensive, as over Rossha. Figure 5 shows the supply of moisture t,o the polar district by poleward-pointmg wind arrows; but there is also a vapor supply and con- densation at the boundary between westerly and easterly winds in the latter district, as has been explained above. The following observational facts lend support to the scheme >resented in figure 5. The cirectioni of the air currents at the upper cloud layer is seen by ins ection of figure 4. In the upper layers the wind follows tI: e isobars, a roximately, and in such a manner that in the Southern !8eniisphere they have the low center on the right. hand. The probable course of the isobars has thus been drawn froni the available ant- arctic observations on clouds and bear these facts in mind. In addition, it has been reco nized that Shackleton and hmundaen niet with southeryf winds on the htarctic Plateau. When one studies tlie upper level isobars and winds, as thus restored, it seems not difficult to explain the suste- nance of the inland ice within the nucleus of Antarctica; for it appears that in the sphere of the upper polar whirl there is an inflowing current of air and water vapor. The FIG.4.-C(keteh of the IsObSTS at the 4,ooO-m. level within the sou!.h polar region. observations of the upper clouds at the marginal stat.ions Arrmshow averaxe dlreiltion of the upper clouds and the prevallmg winds on the justify the conclusion t-liat there is an intake of air at plateau. higher levels over t,he district between Weddell Sea and By making ccrtain assumptions regarding the distri- Wilkes Land, i. e., on the Indo-Atlantic side of the South bution of temperature and pressure one may calculate Polar reaions J and perhaps a siniilarinta.keover the district the up er limit of the anticyclone. From this it appears east of #ass sea to the vicinity of the ~cjgicadriftjourney. that tfk litis less than 2,000 ni. during the greater Conse uently the principal iinportation of water vapor portion of the year, or that it lies below the mean level of will ta?E e place on this aide of the South Polar regon. the south polar continent. Accordingly t-here must be Where the inflowin ’ air strikes against mountain ranges extensive areas of Antarctica that a1wa.p lie higlicr than it will be compellet7 t.o give up the a ueous vn or it is the level of the anticyclone and reach up into the levels carrying. The re ion between Wedde1 1 Sea anB Wilkes of the polar c clonic whirl which dominates the upper air Land is heavily &w.iated, as is also King Edward VI1 strata of the%yher latitudes wherein there is n general Lnnd farther enst; perhaps this is the reason for the glacia- west-to-east tur movement. tion. The com ensating outflow of the now moisture-poor 8’ e 5 presents a diagrammatic cross section of tlie air seems to taP re place, on the other hand, c.hiefl on the &utY Polar regions. The curved lines show the course of west side of Ross Sea snd of Weddell Sea. Here tie ujper the isobars at various altitudes. In the vicinity of the winds are frequently froni the south or southwest, an the South Pole the isobars of the lower layers are arched up- storiny southwest winds of Snow Hill also indicate a lively ward, as is characteristic of an anticyclonic distribution. exportation of air from the Antarctic regon.

Unauthenticated | Downloaded 10/01/21 04:29 PM UTC 230 MON”HLY WEATHER REVIEW. APRIL,1014 The transition to the new unit is facilitated for the u8e.r The very dry air peculiar to the west side of Ross Sea, of the British Daily Weather and which =kea itself felt as a characteristic peculi- first age, which presents the arity of the climate, ma then perhaps be explained as duceCf readings in inches of a the result of this district 9ying in the lee of Victoria Land latitude 45’. Further help is offered on the inside ages and of East Antarctica in general. The westerly currents by a graphic scale com aring the reduced mercurial %am- of the polar whirl, depnved of their moisture by the metric readings in incR e8 mth the millibars used on the heights of East Antarctica, attain this district in a desic- ad’acent maps. On the daily charts themselves the cated condition which still characterizes them when is0i ars are drawn for intervals of 5 millibars, but they are they leave the south olar regions. The stormy south- numbered in centibars and the old-style readings in inches west winds of Snow !&I are also extraordinarily dry, are entered at one end of the line At first it may cause yet of such a low temperature as is only to be ex lained a slight inconvenience to find the tabulated re orts on If they descend from some great reservoir of coT d, viz, pages 1 and 4 presentin the pressures in millif ars and the high-lying central portions of Antarctica the 24-hour change in “%alf-millibars” while the charts use centibars; but no doubt the habitual readers of the Report will soon become familiar with this demonstration of the great convenience of a rational decimal system of notation. In this connection it is interesting and encouraging to note that simultaneously with the chan e to B’erknes’s “millibar” comes the change to “mifhneter’j in the column headed Rainfall. It gives us grounds for ho e that eventually the English-speakin races may as0P FIQ. 5.-Di ammatic CMBB section of the wuth polar regtons to ahow the positlon adopt a thermometric scale that wi combine all the of the IXk surfaces and the dirwtlon of the wind.9. Am& &ow the nieridional K components of the wind; shaded are88 how the region of pvalling eastediw advantages of the Fahrenheit and the centigrade scales. Altitudes In meters. Recent discussions in the United States make it of This concept that the fixed land maases of the sbuth s ecial interest to remark here that the continuance of polar regions are of considerable altitude, that they extend t1 e Beaufort scale of wind force still seems justified in up into a suprapolar c clonic whirl, thus solves in a the present improved Daily Weather Re ort. general way the difficu9 ty of accounting for the ice- In the following paper the Weather B ureau presents covered condition of central Antarctica. It must be its recently adopted standard tables €or conver the task of future expeditions to secure the detailed ard barometric readings into millibars.+o. .,3 foundations for the hypothesis and particularly to reveal the secrets of the upper air over the nucleus of the south polar continent. Far-reachii conclusions will CONVERSION OF BAROMETRIC READ-GI INTO STAND- be founded u on this exploration, for in this wa it will ARD UNITS OF PRESSURE. become possit le to secure more intimate know9 edge of the processes which promoted the growth of the great ByRoy N. COVEET. inland ice sheets over Canada and Scandinavia in the Instrument Didelon, Weather Bureau, May glacial period. These ancient ice sheets also reached [Dated 8,1914.l considerable altitudes, and presumably rose above the Atmospheric pressures may be e-qressed in several zone of anticyclonic circulation. It will be in this different ways, vie, as heights in inches, or millimeters, domain of com arative climatology that future antarctic of the barometric column of mercury or other suitable explorations w11.p yield the most valuable results. liquid; as pounds per square inch or grams per square The observation and recording of the mar inal move centimeter of the weight of that column of mercury; or ments of the inland ice of Antarctica will Be of great in absolute units of force. importance in judging secular variations in climate. Values expressed in one way are convertible into yalues These movements and the magnitude of the ice discharge ospressed in each of the other ways. The conversion of furnish a very sensitive scale for measuring the secular at.niospheric pressures, ex ressed in terms of the linear changes in distribution of precipitation. The great height of the mercurial cof umn, into the form commonly extent of the ice-covered area here smooths out both local used in engineering work,. i. e., ressures ex ressed as a differences and transitory anomalies in weather. Only wei ht per unit area, reguwes a Lowled e oP the density the great and enduring climatic changes, whether periodic of t% e mercury or liquid employed. ‘J%e equation for or nonperiodic in character, can find any expression in this conversion is- the thickness and velocity of the inland ice. One of the P=hp, (1) most imperative needs in future antarctic exploration where P= ressure espressed as a weight per unit area, thus seems to be continuous observations of the move- &{eight of the column in linear units, ments of the inland ice at the largest possible number of density of t,he liquid, i. e., the mass of a unit stations along its margin. volume at a standard temperature. The conversion of ressure when ex ressed in linear units of the height oP the mercurial coP umn into dynes C. 0. 8. UNITS IN THE ENGLISH DAILY WEATHER er s uare centmeter or millibars requires values for REPORT. !oth.?he density of mercury, rp, and the acceleration of In the MONTHLY WEATHEZREVIEW for Fcbruary, gravlty, 9. The equation whch gives the pressure in 1914, par 100, Dr. W. N. Shaw mentioned that begin- millibars, Pmb,corresponding to the barometric height, ning mt the issue for May 1 1914, the Meteorologwal A., is- Office would extend the use of 6. G. S. units of pressure to its Daily Weather Report.

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