The South Pole; an account of the Norwegian antarctic expedition in the "Fram," 1910-1912 — Volume 2

CHAPTER II

Re­marks on the Me­te­oro­log­ical Ob­ser­va­tions at Framheim

By B. J. Birke­land

On ac­count of the im­pro­vised char­ac­ter of the South Po­lar Ex­pe­di­tion, the me­te­oro­log­ical de­part­ment on the Fram was not so com­plete as it ought to have been. It had not been pos­si­ble to pro­vide the aero­log­ical out­fit at the time of sail­ing, and the me­te­orol­ogist of the ex­pe­di­tion was there­fore left be­hind in Nor­way. But cer­tain things were want­ing even to com­plete the equip­ment of an or­di­nary me­te­oro­log­ical sta­tion, such as min­imum ther­mome­ters and the nec­es­sary in­struc­tions that should have ac­com­pa­nied one or two of the in­stru­ments. For­tu­nate­ly, among the vet­er­ans of the ex­pe­di­tion there were sev­er­al prac­tised ob­servers, and, notwith­stand­ing all draw­backs, a fine se­ries of ob­ser­va­tions was ob­tained dur­ing ten months’ stay in win­ter-​quar­ters on the Antarc­tic con­ti­nent. These ob­ser­va­tions will pro­vide a valu­able sup­ple­ment to the si­mul­ta­ne­ous records of oth­er ex­pe­di­tions, es­pe­cial­ly the British in Mc­Mur­do Sound and the Ger­man in Wed­dell Sea, above all as re­gards the hyp­some­ter ob­ser­va­tions (for the de­ter­mi­na­tion of al­ti­tude) on sledge jour­neys. It may be hoped, in any case, that it will be pos­si­ble to in­ter­po­late the at­mo­spher­ic pres­sure at sea-​lev­el in all parts of the Antarc­tic con­ti­nent that were tra­versed by the sledg­ing ex­pe­di­tions. For this rea­son the pub­li­ca­tion of a pro­vi­sion­al work­ing out of the ob­ser­va­tions is of great im­por­tance at the present mo­ment, al­though the gen­er­al pub­lic will, per­haps, look up­on the long rows of fig­ures as te­dious and su­per­flu­ous. The com­plete work­ing out of these ob­ser­va­tions can on­ly be pub­lished af­ter a lapse of some years.

As re­gards the ac­cu­ra­cy of the fig­ures here giv­en, it must be not­ed that at present we know noth­ing about pos­si­ble al­ter­ations in the er­rors of the dif­fer­ent in­stru­ments, as it will not be pos­si­ble to have the in­stru­ments ex­am­ined and com­pared un­til we ar­rive at San Fran­cis­co next year. We have pro­vi­sion­al­ly used the er­rors that were de­ter­mined at the Nor­we­gian Me­te­oro­log­ical In­sti­tute be­fore the ex­pe­di­tion sailed; it does not ap­pear, how­ev­er, that they have al­tered to any great ex­tent.

The me­te­oro­log­ical out­fit on the Fram con­sist­ed of the fol­low­ing in­stru­ments and ap­pa­ra­tus:

Three mer­cury barom­eters, name­ly:

One nor­mal barom­eter by Fuess, No. 361 . One Kew stan­dard barom­eter by Adie, No. 889. One Kew ma­rine barom­eter by Adie, No. 764.

Five aneroid barom­eters:

One large in­stru­ment with ther­mome­ter at­tached, with­out name or num­ber. Two pock­et aneroids by Knud­sen, Copen­hagen, one num­bered 1,503. Two pock­et aneroids by Cary, Lon­don, Nos. 1,367 and 1,368, for al­ti­tudes up to 5,000 me­tres (16,350 feet). Two hyp­some­ters by Casel­la, with sev­er­al ther­mome­ters.

Mer­cury ther­mome­ters:

Twelve or­di­nary stan­dard (psy­chrom­eter-) ther­mome­ters, di­vid­ed to fifths of a de­gree (Centi­grade). Ten or­di­nary stan­dard ther­mome­ters, di­vid­ed to de­grees. Four sling ther­mome­ters, di­vid­ed to half de­grees. Three max­imum ther­mome­ters, di­vid­ed to de­grees. One nor­mal ther­mome­ter by Mol­lenkopf, No. 25.

Toluene ther­mome­ters:

Eigh­teen sling ther­mome­ters, di­vid­ed to de­grees. Three nor­mal ther­mome­ters-​by Tounelot, No. 4,993, and Baudin, Nos. 14,803 and 14,804. Two tor­sion hair hy­grom­eters of Rus­seltvedt’s con­struc­tion, Nos. 12 and 14. One cup and cross anemome­ter of Pro­fes­sor Mohn’s con­struc­tion, with spare cross. One com­plete set of pre­cip­ita­tion gauges, with Nipher’s shield, gauges for snow den­si­ty, etc.

Reg­is­ter­ing in­stru­ments:

Two baro­graphs. Two ther­mo­graphs. One hair hy­gro­graph. A num­ber of spare parts, and a sup­ply of pa­per and ink for sev­en years.

In ad­di­tion, var­ious books were tak­en, such as Mohn’s “Me­te­orol­ogy,” the Me­te­oro­log­ical In­sti­tute’s “Guide,” psy­chro­met­ric ta­bles, Wiebe’s steam-​pres­sure ta­bles for hyp­some­ter ob­ser­va­tions, etc.

The ma­rine barom­eter, the large aneroid, and one of the baro­graphs, the four mer­cury sling ther­mome­ters, and two whole-​de­gree stan­dard ther­mome­ters, were kept on board the Fram, where they were used for the reg­ular ob­ser­va­tions ev­ery four hours on the ves­sel’s long voy­ages back­wards and for­wards.

As will be seen, the shore par­ty was thus left with­out mer­cury sling ther­mome­ters, be­sides hav­ing no min­imum ther­mome­ters; the three max­imum ther­mome­ters proved to be of lit­tle use. There were al­so var­ious de­fects in the clock­work of the reg­is­ter­ing in­stru­ments. The baro­graphs and ther­mo­graphs have been used on all the Nor­we­gian Po­lar ex­pe­di­tions; the hy­gro­graph is al­so an old in­stru­ment, which, in the course of its ca­reer, has worked for over ten years in Chris­tia­nia, where the at­mo­sphere is by no means mer­ci­ful to del­icate in­stru­ments. Its clock­work had not been cleaned be­fore it was sent to the Fram, as was done in the case of the oth­er four in­stru­ments. The baro­graphs worked ir­re­proach­ably the whole time, but one of the ther­mo­graphs re­fused ab­so­lute­ly to work in the open air, and un­for­tu­nate­ly the spin­dle piv­ot of the oth­er broke as ear­ly as April 17. At first the clock­work of the hy­gro­graph would not go at all, as the oil had be­come thick, and it was not un­til this had been re­moved by pro­longed se­vere heat­ing (bak­ing in the oven for sev­er­al days) that it could be set go­ing; but then it had to be used for the ther­mo­graph, the mech­anism of which was bro­ken, so that no reg­is­tra­tion was ob­tained of the hu­mid­ity of the air.

The re­sult­ing reg­is­tra­tions are then as fol­lows: from Framheim, one set of baro­grams and two sets of ther­mo­grams, of which one gives the tem­per­ature of the air and the oth­er the tem­per­ature in­side the house, where the barom­eters and baro­graph were placed; from the Fram we have baro­grams for the whole pe­ri­od from her leav­ing Chris­tia­nia, in 1910, to her ar­rival at Buenos Aires for the third time, in 1912.

Of course, none of these reg­is­tra­tions can be tak­en in­to ac­count in the pro­vi­sion­al work­ing out, as they will re­quire many months’ work, which, more­over, can­not be car­ried out with ad­van­tage un­til we have as­cer­tained about pos­si­ble changes of er­ror in the in­stru­ments. But oc­ca­sion­al use has been made of them for pur­pos­es of check­ing, and for sup­ply­ing the on­ly ob­ser­va­tion miss­ing in the ten months.

The me­te­oro­log­ical sta­tion at Framheim was ar­ranged in this way: the barom­eters, baro­graph, and one ther­mo­graph hung in­side the house; they were placed in the kitchen, be­hind the door of the liv­ing-​room, which usu­al­ly stood open, and thus pro­tect­ed them from the ra­di­ant heat of the range. A ther­mome­ter, a hy­grom­eter, and the oth­er ther­mo­graph were placed in a screen on high posts, and with lou­vred sides, which stood at a dis­tance of fif­teen yards to the south-​west of the house. A lit­tle way be­yond the screen, again, stood the wind-​vane and anemome­ter. At the end of Septem­ber the screen had to be moved a few yards to the east; the snow had drift­ed about it un­til it was on­ly 2 1/2 feet above the sur­face, where­as it ought to stand at the height of a man. At the same time the wind-​vane was moved. The screen was con­struct­ed by Lind­ström from his rec­ol­lec­tion of the old Fram screen.

The two mer­cury barom­eters, the Fuess nor­mal, and the Adie stan­dard barom­eter, reached Framheim in good con­di­tion; as has been said, they were hung in the kitchen, and the four pock­et aneroids were hung by the side of them. All six were read at the dai­ly ob­ser­va­tions at 8 a.m., 2 p.m., and 8 p.m. The nor­mal barom­eter, the in­struc­tions for which were miss­ing, was used as a siphon barom­eter, both the mer­cury lev­els be­ing read, and the bot­tom screw be­ing locked fast; the usu­al mode of read­ing it, on the oth­er hand, is to set the low­er lev­el at ze­ro on the scale by turn­ing the bot­tom screw at ev­ery ob­ser­va­tion, where­upon the up­per lev­el on­ly is set and read. The Adie stan­dard barom­eter is so ar­ranged that it is on­ly nec­es­sary to read the sum­mit of the mer­cury. It ap­pears that there is some dif­fer­ence be­tween the at­mo­spher­ic pres­sure val­ues of the two in­stru­ments, but this is chiefly due to the dif­fi­cult and ex­treme­ly vari­able con­di­tions of tem­per­ature. There may be a dif­fer­ence of as much as five de­grees (Centi­grade) be­tween the ther­mome­ters of the two barom­eters, in spite of their hang­ing side by side at about the same height from the floor. On the oth­er hand, the nor­mal barom­eter is not suit­ed to dai­ly ob­ser­va­tions, es­pe­cial­ly in the Po­lar re­gions, and the dou­ble read­ing en­tails greater li­abil­ity of er­ror. That the Adie barom­eter is rather less sen­si­tive than the oth­er is of small im­por­tance, as the vari­ations of at­mo­spher­ic pres­sure at Framheim were not very great.

In the pro­vi­sion­al work­ing out, there­fore, the read­ings of the Adie barom­eter alone have been used; those of the nor­mal barom­eter, how­ev­er, have been ex­per­imen­tal­ly re­duced for the first and last months, April and Jan­uary. The read­ings have been cor­rect­ed for the tem­per­ature of the mer­cury, the con­stant er­ror of the in­stru­ment, and the vari­ation of the force of grav­ity from the nor­mal in lat­itude 45°. The re­duc­tion to sea-​lev­el, on the oth­er hand, has not been made; it amounts to 1.1 mil­lime­tre at an air tem­per­ature of -10° Centi­grade.

The ob­ser­va­tions show that the pres­sure of the at­mo­sphere is through­out low, the mean for the ten months be­ing 29.07 inch­es (738.6 mil­lime­tres). It is low­er in win­ter than in sum­mer, Ju­ly hav­ing 28.86 inch­es (733.1 mil­lime­tres), and De­cem­ber 29.65 inch­es (753.3 mil­lime­tres), as the mean for the month, a dif­fer­ence of 20.2 mil­lime­tres. The high­est ob­ser­va­tion was 30.14 inch­es (765.7 mil­lime­tres) on De­cem­ber 9, and the low­est 28.02 inch­es (711.7 mil­lime­tres) on May 24, 1911; dif­fer­ence, 54 mil­lime­tres.

Air Tem­per­ature and Ther­mome­ters.

As has al­ready been stat­ed, min­imum ther­mome­ters and mer­cury sling ther­mome­ters were want­ing. For the first six months on­ly toluene sling ther­mome­ters were used. Sling ther­mome­ters are short, nar­row glass ther­mome­ters, with a strong loop at the top; be­fore be­ing read they are briskly swung round at the end of a string about half a yard long, or in a spe­cial ap­pa­ra­tus for the pur­pose. The swing­ing brings the ther­mome­ter in con­tact with a great vol­ume of air, and it there­fore gives the re­al tem­per­ature of the air more read­ily than if it were hang­ing qui­et­ly in the screen.

From Oc­to­ber 1 a mer­cury ther­mome­ter was al­so placed in the screen, though on­ly one di­vid­ed to whole de­grees; those di­vid­ed to fifths of a de­gree would, of course, have giv­en a sur­er read­ing. But it is ev­ident, nev­er­the­less, that the toluene ther­mome­ters used are cor­rect to less than half a de­gree (Centi­grade), and even this dif­fer­ence may no doubt be ex­plained by one ther­mome­ter be­ing slung while the oth­er was fixed. The ob­ser­va­tions are, there­fore, giv­en with­out any cor­rec­tions. On­ly at the end of De­cem­ber was ex­clu­sive use made of mer­cury ther­mome­ters. The max­imum ther­mome­ters tak­en proved of so lit­tle use that they were soon dis­card­ed; the ob­ser­va­tions have not been in­clud­ed here.

It was due to a mis­un­der­stand­ing that mer­cury ther­mome­ters were not al­so used in the first half-​year, dur­ing those pe­ri­ods when the tem­per­ature did not go be­low the freez­ing-​point of mer­cury (-89° C.). But the toluene ther­mome­ters in use were old and good in­stru­ments, so that the ob­ser­va­tions for this pe­ri­od may al­so be re­gard­ed as per­fect­ly re­li­able. Of course, all the ther­mome­ters had been care­ful­ly ex­am­ined at the Nor­we­gian Me­te­oro­log­ical In­sti­tute, and at Framheim the freez­ing-​point was reg­ular­ly test­ed in melt­ing snow.

The re­sults show that the win­ter on the Bar­ri­er was about 19.° C. (21.6° F.) cold­er than it usu­al­ly is in Mc­Mur­do Sound, where the British ex­pe­di­tions win­ter. The cold­est month is Au­gust, with a mean tem­per­ature of -44.5° C. (-48.1° F.); on four­teen days dur­ing this month the tem­per­ature was be­low -50° C. (-58° F.). The low­est tem­per­ature oc­curred on Au­gust 13: -58.5° C. (-73.3° F.); the warmest day in that month had a tem­per­ature of -24° C. (-11.2° F.).

In Oc­to­ber spring be­gins to ap­proach, and in De­cem­ber the tem­per­ature cul­mi­nates with a mean for the month of -6.6° C. (+2O.l° F.), and a high­est max­imum tem­per­ature of -0.2° C. (+31.6° F.). The tem­per­ature was thus nev­er above freez­ing-​point, even in the warmest part of the sum­mer.

The dai­ly course of the tem­per­ature — warmest at noon and cold­est to­wards morn­ing — is, of course, not no­tice­able in win­ter, as the sun is al­ways be­low the hori­zon. But in April there is a sign of it, and from Septem­ber on­ward it is fair­ly marked, al­though the dif­fer­ence be­tween 2 p.m. and the mean of 8 a.m. and 8 p.m. on­ly amounts to 2° C. in the month­ly mean.

Hu­mid­ity of the Air.

For de­ter­min­ing the rel­ative hu­mid­ity of the air the ex­pe­di­tion had two of Rus­seltvedt’s tor­sion hy­grom­eters. This in­stru­ment has been ac­cu­rate­ly de­scribed in the Me­te­orol­ogis­che Zeitschrift, 1908, p. 396. It has the ad­van­tage that there are no axles or sock­ets to be rust­ed or soiled, or filled with rime or drift-​snow.

Fig. 1.

Fig. 2.

Fig. 3.

The two horse­hairs (h, h’) that are used, are stretched tight by a tor­sion clamp (Z, Z’, and L), which al­so car­ries the point­er; the po­si­tion of the point­er varies with the length of the hairs, which, again, is de­pen­dent on the de­gree of hu­mid­ity of the air. (See the di­agrams.) These in­stru­ments have been in use in Nor­way for sev­er­al years, es­pe­cial­ly at in­land sta­tions, where the win­ter is very cold, and they have shown them­selves su­pe­ri­or to all oth­ers in ac­cu­ra­cy and dura­bil­ity; but there was no one on the Fram who knew any­thing about them, and there is there­fore a pos­si­bil­ity that they were not al­ways in such good or­der as could be wished. On Septem­ber 10, es­pe­cial­ly, the vari­ations are very re­mark­able; but on Oc­to­ber 13 the sec­ond in­stru­ment, No. 12, was hung out, and there can be no doubt of the cor­rect­ness of the sub­se­quent ob­ser­va­tions.

It is seen that the rel­ative hu­mid­ity at­tains its max­imum in win­ter, in the months of Ju­ly and Au­gust, with a mean of 90 per cent. The dri­est air oc­curs in the spring month of Novem­ber, with a mean of 73 per cent. The re­main­ing months vary be­tween 79 and 86 per cent., and the mean of the whole ten months is 82 per cent. The vari­ations quot­ed must be re­gard­ed as very small. On the oth­er hand, the fig­ures them­selves are very high, when the low tem­per­atures are con­sid­ered, and this is doubt­less the re­sult of there be­ing open wa­ter not very far away. The dai­ly course of hu­mid­ity is con­trary to the course of the tem­per­ature, and does not show it­self very marked­ly, ex­cept in Jan­uary.

The ab­so­lute hu­mid­ity, or par­tial pres­sure of aque­ous vapour in the air, ex­pressed in mil­lime­tres in the height of the mer­cury in the same way as the pres­sure of the at­mo­sphere, fol­lows in the main the tem­per­ature of the air. The mean val­ue for the whole pe­ri­od is on­ly 0.8 mil­lime­tre (0.031 inch); De­cem­ber has the high­est month­ly mean with 2.5 mil­lime­tres (0.097 inch), Au­gust the low­est with 0.1 mil­lime­tre (0.004 inch). The ab­so­lute­ly high­est ob­ser­va­tion oc­curred on De­cem­ber 5 with 4.4 mil­lime­tres (0.173 inch), while the low­est of all is less than 0.05 mil­lime­tre, and can there­fore on­ly be ex­pressed by 0.0; it oc­curred fre­quent­ly in the course of the win­ter.

Pre­cip­ita­tion.

Any at­tempt to mea­sure the quan­ti­ty of pre­cip­ita­tion — even ap­prox­imate­ly — had to be aban­doned. Snow­fall nev­er oc­curred in still weath­er, and in a wind there was al­ways a drift that en­tire­ly filled the gauge. On June 1 and 7 ac­tu­al snow­fall was ob­served, but it was so in­signif­icant that it could not be mea­sured; it was, how­ev­er, com­posed of gen­uine flakes of snow. It some­times hap­pened that pre­cip­ita­tion of very small par­ti­cles of ice was no­ticed; these grains of ice can be seen against the ob­ser­va­tion lantern, and heard on the ob­serv­er’s head­gear; but on re­turn­ing to the house, noth­ing can be dis­cov­ered on the cloth­ing. Where the sign for snow oc­curs in the col­umn for Re­marks, it means drift; these days are in­clud­ed among days of pre­cip­ita­tion. Sleet was ob­served on­ly once, in De­cem­ber. Rain nev­er.

Cloudi­ness.

The fig­ures in­di­cate how many tenths of the vis­ible heav­ens are cov­ered by clouds (or mist). No in­stru­ment is used in these ob­ser­va­tions; they de­pend on per­son­al es­ti­mate. They had to be aban­doned dur­ing the pe­ri­od of dark­ness, when it is dif­fi­cult to see the sky.

Wind.

For mea­sur­ing the ve­loc­ity of the wind the ex­pe­di­tion had a cup and cross anemome­ter, which worked ex­cel­lent­ly the whole time. It con­sists of a hor­izon­tal cross with a hol­low hemi­sphere on each of the four arms of the cross; the open­ings of the hemi­spheres are all turned to­wards the same side of the cross-​arms, and the cross can re­volve with a min­imum of fric­tion on a ver­ti­cal ax­is at the point of junc­tion. The ax­is is con­nect­ed with a record­ing mech­anism, which is set in mo­tion at each ob­ser­va­tion and stopped af­ter a lapse of half a minute, when the fig­ure is read off. This fig­ure de­notes the ve­loc­ity of the wind in me­tres per sec­ond, and is di­rect­ly trans­ferred to the ta­bles (here con­vert­ed in­to feet per sec­ond).

The month­ly means vary be­tween 1.9 me­tres (6.2 feet) in May, and 5.5 me­tres (18 feet) in Oc­to­ber; the mean for the whole ten months is 3.4 me­tres (11.1 feet) per sec­ond. These ve­loc­ities may be char­ac­ter­ized as sur­pris­ing­ly small; and the num­ber of stormy days agrees with this low ve­loc­ity. Their num­ber for the whole pe­ri­od is on­ly 11, fair­ly even­ly di­vid­ed be­tween the months; there are, how­ev­er, five stormy days in suc­ces­sion in the spring months Oc­to­ber and Novem­ber.

The fre­quen­cy of the var­ious di­rec­tions of the wind has been added up for each month, and gives the same char­ac­ter­is­tic dis­tri­bu­tion through­out the whole pe­ri­od. As a mean we have the fol­low­ing ta­ble, where the fig­ures give the per­cent­age of the to­tal num­ber of wind ob­ser­va­tions:

N. N.E. E. S.E. S. S.W. W. N.W. Calm.

1.9 7.8 31.9 6.9 12.3 14.3 2.6 1.1 21.3

Al­most ev­ery third di­rec­tion is E., next to which come S.W. and S. Re­al S.E., on the oth­er hand, oc­curs com­par­ative­ly rarely. Of N., N. W., and W. there is hard­ly any­thing. It may be in­ter­est­ing to see what the dis­tri­bu­tion is when on­ly high winds are tak­en in­to ac­count — that is, winds with a ve­loc­ity of 10 me­tres (32.8 feet) per sec­ond or more. We then have the fol­low­ing ta­ble of per­cent­ages:

N. N.E. E. S.E. S. S.W. W. N.W.

7 12 51 10 4 10 2 4

Here again, E. is pre­dom­inant, as half the high winds come from this quar­ter. W. and N.W. to­geth­er have on­ly 6 per cent.

The to­tal num­ber of high winds is 51, or 5.6 per cent. of the to­tal of wind ob­ser­va­tions.

The most fre­quent di­rec­tions of storms are al­so E. and N.E.

The Au­ro­ra Aus­tralis.

Dur­ing the win­ter months au­ro­ral dis­plays were fre­quent­ly seen — al­to­geth­er on six­ty-​five days in six months, or an av­er­age of ev­ery third day — but for want of ap­pa­ra­tus no ex­haus­tive ob­ser­va­tions could be at­tempt­ed. The records are con­fined to brief notes of the po­si­tion of the au­ro­ra at the times of the three dai­ly ob­ser­va­tions.

The fre­quen­cy of the dif­fer­ent di­rec­tions, reck­oned in per­cent­ages of the to­tal num­ber of di­rec­tions giv­en, as for the wind, will be found in the fol­low­ing ta­ble:

N. N.E. E. S.E. S. S.W. W. N.W. Zenith.

18 17 16 9 8 3 8 13 8

N. and N.E. are the most fre­quent, and to­geth­er make up one-​third of all the di­rec­tions record­ed; but the near­est points on ei­ther side of this max­imum — E. and N.W. — are al­so very fre­quent, so that these four points to­geth­er — N.W., N., N.E., E. — have 64 per cent. of the whole. The rarest di­rec­tion is S.W., with on­ly 3 per cent. (From the po­si­tion of the Mag­net­ic Pole in re­la­tion to Framheim, one would rather have ex­pect­ed E. to be the most fre­quent, and W. the rarest, di­rec­tion.) Prob­ably the ma­te­ri­al be­fore us is some­what scanty for es­tab­lish­ing these di­rec­tions.

Me­te­oro­log­ical Record from Framheim.

April, 1911 — Jan­uary, 1912.

Height above sea-​lev­el, 36 feet. Grav­ity cor­rec­tion, .072 inch at 29.89 inch­es. Lat­itude, 78° 38′ S. Lon­gi­tude, 163° 37′ W.

Ex­pla­na­tion of Signs in the Ta­bles.

SNOW sig­ni­fies snow.

MIST ,, mist.

AU­RO­RA ,, au­ro­ra.

RING­SUN ,, large ring round the sun.

RING­MOON ,, ,, ,, moon.

STORM ,, storm

sq. ,, squalls

a. ,, a.m.

p. ,, p.m.

I., II, III., sig­ni­fy re­spec­tive­ly 8 a.m., 2 p.m., and 8 p.m.

° (e.g., SNOW°) sig­ni­fies slight.

2 (e.g., SNOW2) ,, heavy.

Times of day are al­ways in lo­cal time.

The date was not changed on cross­ing the 180th merid­ian