, DECEMBER,1906. MONTHLY WEATHER REVIEW. 549

On the same side of the equator whirls of the same kind storms, sometimes as much as five hundrecl miles across, that (cyclones for instance) always turn or rotate around their occur in the Bay of Bengal mil the Indian Ocean. Storms centers in the same direction. In our Northern Hemisphere the like these also occur in the West Indieh (south and southeast direction of tlie inward and upward spiral movement of the of the ), wliere they were named hurricanes by air circulating around a cyclone is always opposite to the the CarilJlwan Indians who inhabited the islnncls uf the West direction of the movement of the hands of a watch or clock as Indies 11-lieu they were discoverecl l~yEuropeans, :tnd the name it lies face upward, that is to say, contraclockwise. In the wxs adopted 1)y tlie early Spaiiihli and Portuguese navigators Southern Hemisphere, the whirling movement of cyclones is and has been used ever since. Storms of the saine kind occur with the hands of a watch, or clockwise. in the Philippines ant1 on the Chinese coast, wliere they have Anticyclones, contrary to cyclones in other respects. are 1)een called typhoons froiii ancient tiiiies. also contrary to thein in the matter of the direction of nhirling. The name cyclone mns invented to descri1)e the whirling Anticyclones rotate clockwise in the Northern Heinispliere, cliarituter of these large wliirlwiuds tliat Englishmen found in ancl counterclockwise in the Southern Hemisphere. Of course Inclin. It was brought home tu England 1)y them, and the large there is a reason for this rule about the direction of whirling, whirliqg masses of air that are carried along from west to east and that is that the clirection of the whirl is given to it by tlie were called cyclones, and now the word cyclone belongs prop- direction of the whirling of the earth rotating on its axis. erly to large ~vliirlwinc7stwo or tliree thousand miles in diitmeter. s If you have a stationary washbowl with an outlet nt tlie The word torn:tdo is a Spanish word meaning ‘‘ twister,” and bottom, or even a large round bottle turned upside d(wn, yon is npl&ecl to the dangerous wliirlwinds that tear down houses can make whirlpools for btucly by filling the howl or bottle and kill 1)eople. They are very sinall c.oiiip:wed with the liur- with water, and then when you pull out the stopper tlie water ric.:me ancl cyclone, being generaly less than half a mile in will start whirling around. climnrter mcl are rarely carried more than forty or fifty miles, The broad aerial stream that is generally flowing from west to and do not 1aht idtogether more than an hour or SO before they east over the United States appitrently carries cyclones and anti- die a\\ ;~yitiicl disappear. They titlie ouly a few seconds to pms cyclones along with it very much as the brook or river carries o\ er any given 1)oint. Cyclones and hurricanes travel for many along its whirlpools. It is this succession of ‘L highs ” and chys and go thousi~udsof miles ancl take frtm a day to three lows ” with their opposite kinds of weather and wild tliitt or four dxyh to 1)nss over :t place. It is evident, then, that the brings us our frequent changes froiii rainy to clear, warm to cyclone tiiid the t,oriido are two very clif-ferent things, their cold, and south wind to north wind. himilarity being tliat they are both whirling masses of air. The word cyclone belongs to the very large whirls in the The liouse c:tt and tlie tiger are alike in more respects, but atmosphere that I have described. There are other mixller there is no one who ~oulclcall n cat :I tiger, so the tornado atmospheric whirls that have special naines; these are the slioulrl not be called H cyclone.-E. K. JT. hurricane, typhoon, tornado, and waterspout. I wish especi:illy to make very clear to you the dif-ference between a cyclone ani1 a tornado, because many people use the word cyclone when CORRIGENDUM. they mean tornado, and when others use the word cyclone MowrHLT WEATHERREVIEW for July, 1905, Vol. SSSIII,page properly they are not understood. The word cyclone wah firht 318, line 12: For ‘< teiuperature over Iceland ’’ read “pressure used about the year 1840 as :i name for very large \\hirling over Iceland. ”

THE WEATHER OF THE MONTH. By Mr. WM.B. STocKaraN. Chief, Division of Meteorological Records. PRESSURE. inch over the greater portion of the slope and Plateau regions. Over the entire United States the iiienn pressure for Decem- The distribution of mean atmospheric pressure is graphically ber exceeded that of the preceding month, except in the south- shown on Chart VI11 and the average values and departures ern part of the Peninsula of . where 110 change occurred. from normal are shown in Tables I aiicl V. The greatest increases occurred over the slope, Plateau, and The mean pressure for the month was highest over the middle and south Pacific districts, where they ranged from middle and northern Plateau and the western portions of the +.lo to +.SG inch, the estreiiie changes, +.%J to +.%inch, middle and northern slope regions, with the crest over southeru occurring over southwestern Wyoming. northwestern Colo- Idaho, southwestern Wyoming, ant1 northeastern Nevada. The rado, central and uorthern Utah, northern Nevada (the crest), contour of the isobars inclosing this area of highest Eean northeastern California, and southern Idaho. pressure closely Rpproached the norinal for the month, but the values were considerably greater. The area of secondary norlntll high pressure overlging the region about the southern TEMPERATURE OF THE AIR. portion of the Allegheny Mountains is not indicated on the The mean temperature for the month was above the normal chart for this month. froin central Montana, northeastern Wyoming, and western The mean pressure was lowest over northeastern New Eng- I

Unauthenticated | Downloaded 09/25/21 03:11 AM UTC 550 MONTHLY WEATHER REVIEW. DECEMBER,1906 the excess amounted to + 6.3'. From eastern west- PRECIPITATION. ward to eastern California, and over the middle slope antl The distribution of total monthly precipitation is shown on Plateau and the southern portions of the northern slope and Chart 111. Plateau regions, the cleiiciencies ranged from -4.OOto -11.6'; The precipitation was above the normal in southwestern -6.0°, or more, over northwestern , central and east- Maine, southeastern New Hampshire, off Rhode Island, in ern Tesas, ancl the middle slope and Plateau regions, antl southern Connecticut, extreme southerii Sew Pork, southern -11.6' over northern Nevada. Pennsylvania, New Jersey, Marj land, District of Columbia, By geographic: districts the temperature n as norind in the , North Carolina, except the extreme eastern part, north Pacific region; slightly below in the Soutli dtlnntio South Carolin:&,, Florida, hlal,ama, extreme southern States, Florida Peninsula, Ohio Vitlley ancl , iiiiddle Mississippi, Louisiana, eastern and extreme western Tesas, slope, northern Plateau, ancl niiclclle and south Pacific regions, Tennessee, except the extreme southwestern part, , and considerably below in the middle RU~scIuthern Plateau the extreme southern portions of Indiana aucl Illinois, north- and southern slope regions, adthe Gulf States. In the central Upper Michigan, and about tlie eastern end of Lake Middle Atlantic States, upper Rlississippi :ind Missouri valleys Ontario; elsewhere the precipitation for the month \vas below ancl northern slope region the iiiean teiuperature was slightly the normal. above the normal, and LO', or more, above iioriiial in Nen Over the region from the District of Columbia southward England, the Lake region, ancl North Dakota. over Floricla and southwestward over houtheastern Louisiana Maximuin teniperatures of SO", or higher, n ere rel)ortedfroiii the excesses generally amounted to +2.o inches, or more; the greiiter portion of the Peninsulic of Florida, ant1 of 70" to +4.0 to + 6.0 inches over western South C'arolina and central SOo at stations approxiniately 100 miles inland huiii tlie co:ists (feorgia; solnewhat niore than + 10.0 inches over the extreme of the South Atlantic and Gulf States, in the lo\\ er Rio Graucle southeastern portion of Louisiana, arid + 8.4 to +13.4 inches Valley, and from southwestern drizonn, nnd the boutliern thiril over the southern third of the Peninsula of Florida. of C'alifornia. As a rule, the deficiencies mere less than -1.0 inch. except Freezing temperatures occurretl, except o\ er the greater on the Pacific coast, where they ranged from -2.0 to -5.6 portion of the Florida Peninsula, at places on the iimuec1i:ite inches. Deficiencies of -1.0 to -2.0 inches were reportecl coast of the nest Cfdf Stateb, ancl in extreme southwestern from , the northwestern portions of and Arizona, and extreme southwestern California. Missouri, west-central Mississippi, northeastern Illinois, north- ern Indiana, west-centra1 Ohio, northeastern Wisconsin, and Mininiuiii temperatures of zero, or lower, n ere reported gen- eastern RIinnesota. and somewhat more than -2.0 inches from erally from the following districts: Northern portions of New extreme northwestern Pennsylvania. England and New western Upper R.Iicliig.an, Wisconsin, York, By geographic districts the precipitntion for the month Minnesota, Iowa, north-central Missouri, northern Nebraslia, was slightly below t8he normal in the Lake region, North the Dakotas, Montana, Wyoming, Colorado, northesterii Ne\\ Dakota, upper Mississippi ancl Missouri valleys, northern and Mexico, northeahtern Arizona, northern Utah, central nul middle slope, and the Plateau regions, aiicl 2.2 to 3.2 inches northern Nevada, ancl mutheastern Idalio. Teliiperatiires of below the normal in the Pacific districts. The total for the -30' to -&Go were reported from sontli-central C'o1i)rdo. mouth was slightly above the normal in , the The average temperatures for the several geographic clistricts Miclclle Atlantic and west Gulf States, Ohio Valley nncl Ten- and the departures from the normal values are shown in the nessee, and southern slope; iiearly 3.0 inches above the nor- following table: mal in the South Btlantic and east Gulf States, and inore thau Average temperaturea and departurea from normal. 6.0 inches above in the Florida Peninsula. Average precipdatwn and depurture from the nomnal. Average tempera- Average tures lepartores Averuge. Districts. for the since c 11 rre n t January 1. month. Accum u- Current lated ~- ~~ -~ month. since 0 0 , Jau.1. New En land ...... 8 31.8 -0. E __~ Middle hmtic...... 12 37.4 -0. :; hrhr.8. Itiches. Inehea. South Atlantic ...... 10 46.0 -0. 2 I New Ennland...... I 8 +O. 5 - h. i Florlda Peninsula* ...... 8 60. 4 i 0. G bfiddle%tiintic...... 12 4. ou 12s 46. 3 --o. 6 South Atlantic ...... 10 6. Od 175 45. 6 --0.5 Florida Peniiisula* ...... a 37. 1 -0.6 -7.4 -0.6 7. 2s 159 32.5 t2.0 East Gulf...... 9 -7.7 -0. 1; West Gulf...... 7 3. 42 115 27.4 + a0 + 1.0 +o. I Ohio Valley and Tennesaee...... 11 3.67 ~ 1'10 +O. 6 1.6 15. 8 + BY +1$5 t1.1 Lower Lake. -0.7 %per Mississippi Valley. 11 29.1 1. 7 3 ...... 8 I 15.5 ...... -t - -. 4.2 Upper Lake ...... 10 ssouri Valley ...... 11 30.4 t1.8 +I.] +o. 1 E 26 Northern Slope. 7 24.3 +0.2 +1.0 North Dakota...... to. 1 perhlississippi Valley...... 11 1. 1!1 Middle Slope ...... 6 33. 3 -1.6 -4.3 -0.4 lasouri Valley ...... 11 n. D 3'' Southern S ope *...... 6 37.4 - 4.0 -13.2 -1. 1 Northern Slope.. 7 0. 13 '15 13 36.2 -8.9 ...... Soiithern Plateau * ...... -3.5 -0. 7 Middle 8looe. 0. 19 21 -0. 7 Middle Plateau 8 22.2 -5.3 -3.5 ...... 6 + 4.4 ...... -0.3 Southern &ne*...... 6 1.28 10s +O.I +8.O Northern Plateau*...... 12 2s. E 1.7 7.5 +O. G 1 - + Southern Pla'teau 13 I1 XI RII -0.2 North Pacific., 7 41.9 0.0 +7.7 * ...... + 7.8 ...... +o. 6 Middle Plateau ...... 0.59 47 -0.6 O.!) Middle Pacific...... 5 46. 7 -1.7 +6.6 +(I. G * 8 + South PaciEc 4 F!. 2 Northern Plateair*...... 12 0.95 54 -0. E - 2. !I ...... -0.6 +4.5 to.4 Norfh Pacific...... 7 6.25 -2.2 -12.1 Middle Pacific...... 5 2.24 -3. 2 - 9.0 * Regular Weather Bureau and selected cooperative stations. South Pacific...... 4 0.38 -2.7 ' + 0.8 In Canada.-Prof. R. F. Stupart says: *Regular Weather Bureau nnd selected cooperative atations. Victoria, B. C., report8 that the teiuperature was just average, bJut The limit of snowfall estenclecl as far south as southeastern elsewhere throughout the Dominion the arerage was exceeded, and in North Carolina, central , the northern thircl of most localities to a inarked extent. In northern British Columbia the positive departure was 8'. In glberta, Saskatchewnu, and Manitubit it Georgia, northern fourth of Alabama, estreine northern Mis- varied from 5O to 10'; in Ontario from 2G to 6'; in Quebec and the ILari- sissippi, extreme northwestern Louisiana, and northern and time Provinces it was from 1' to 4'. western .

Unauthenticated | Downloaded 09/25/21 03:11 AM UTC DECEMBER,1906. MONTHLP WEATHER REVIEW. 551 The greatest amount of snow fell in northern Maine, Upper CLEAR SKY AND CLOUDINESS. Michigan, northern Wisconsin, the central portions of En- The cloudiness was above the average in New England, the nesota and North Dakota, and the micldle and northern por- -4tlantic and east Gulf States, Florida Peninsula, Ohio Valley tions of the western mountains. and Tennewee, southern slope, northern and southern Plateau, The total depth and the southern limit of snowfall are and the north Pacific regions. In the remaining districts it depicted on Chart S, and the depth of snow on groiincl at end was below the normal. of month on Chart SI. The distribution of clear sky is graphically shown on Chart 1)t Cunado.-Professor Stupart says : IV, and the numerical values of average daylight cloudiness, both for individual stations and by geographic districts, appear The precipitation was deficient throughout Canada if we except a few isolated localities. as follows: Halifax, a positive departure of 1.5 in Table I. inches; Chathain, N. B., 1.1 inches; Minnedosa, ail excess of U 2 of an The averages for the various districts, with departures from inch, and Montreal 0.1 of an inch. The negative departureb were the normal, are shown in the following table: in certain dibtricts very pronounced. Thib was especially the case in Vancouver Iblalld and over the lower mainland, Victoria recording a Average cloudineaa and departurea from the normal. deficiency of 5.2 inches and New Westminster3 5 inches. In the North- west Provinces the precipitation, which was probably all mow, was very light, several localities reporting none. In Outario the deficiency in precipitation was in many parts from 1 to 2 inches. In Quebec the rain- fall was generally much below the usual amount, but on the other hand the snowfall was locally in excess of the average. In the Maritiiur New England ...... 6.0 t 0.2 Missouri Valley ...... 3. 7 - 1. .I Provinces Tarmouth was 2.0 inches below the average precipitation, Middle Atlantic...... 5. '5 + 0.4 Northern Slope...... 4. 5 - 0. 1 110 South Atlantic 1,s Middle Slope 0.2 and St. .John 0. 9 inch. At the close of the ini~nththere was siiow on ...... 2 5 + ...... 3.8 - the ground in southern Alberta ; elsewhere in the Northwest Provinceb, Florida Peniusula...... ,.? + 2.6 Southern Slope...... 4. 7 + 0.; East Gulf ...... fi.2 + 1.0 Southern Plateau ...... 3.2 +O." however, the covering was from 1 to 5 inches. In Ontario there was West Gulf...... 5.1 - 0. 2 Middle Plateau ...... 4.3 - 0.8 none in the southern parts, but 6 to 12 inches locally in the northern Ohio Valley and Tennessee.. . 6.5 + 0.4 Northeru Plateau ...... 7.1 + 0.3 parts. In Quebec there was 10 iuchea in the western portion, illcreasing Lower Lake...... 7. !? - 0. 4 North Pacific ...... 8.3 + 1.0 Upper Lake...... 6. fi - 0.5 Middle Pacific ...... 5.3 - 0.1 to 20 inches in the eastern portion. 111 the Maritinie Prorinceh there North Dakota ...... 5.0 - 0.2 South Pacific...... 3.4 - 1.0 was 12 to 16 inches in many parts of New Brunsmicli, diuiinisliing to n Upper Mississippi Valley.. ... 4. 7 - 1.0 few inches or more in southern Nova Scotia. In British Columbia there appears to have been a considerable quantity of snow on most of the mountain ranges. WIND. The maximum wind velocity at each Weather Bureau station HUMIDITY. for a period of five minutes is given in Table I, which also gives The relative humidity was normal in New England mid the the altitude of Weather Bureau anemometers above ground. upper Mississippi Valley; slightly below the normal iu the Following are the velocities of 50 miles and over per hour middle and South Atlantic and Gulf States, Ohio Valley and registered during the month: Tennessee, upper Lake region and middle slope; considerably Maximum wind velocities. ~ - below in the Missouri Valley, and much below in the micldle d and south Pacific regions. It was slightly above in the lower .-4 3 Statious. 0 0 Lake region, North Dakota, middle Plateau, and north Pacific - E ;-" s regions, and considerably above in t,he northern Plateau, - - southern and northern slope regions, and the Florida Penin- Atlnuta, 1;s ...... IO 50 ll\V. XItnint \Venther, Va.. ... 10 64 ll\V. sula, and much above in the southern Plateau region. Bled Island, R. I...... 5 50 ll\V. Dll...... 23 fil IlW. D~ ...... 10 60 11. Ih8 ...... 30 63 nw. The averages by districts appear in the following table: e. Nnutuckot, hlass...... IO 64 n. \v . 110 ...... 21 59 e. Average relative humidity and &parturea from the nmal. s\v. Ih?...... 30 52 w. E \I,. New York, N. T ...... 4 53 IlW. sw. 6-1 IIW. 4Do $22 w. 52 \v . Districts. Districts. S\Y. 50 9. Y w. 50 s. j SW. 56 R. --I-- --I-- s S\V. 68 9. IIW. B'L ye. f Eastport, Me ...... 3 50 I]*. 54 yw. 76 New Enilaud...... 0 Mimouri Valley ...... 71 -4 El Paso, Teu ...... 21 66 w . 66 8. Middle tlantic...... 72 - 3 Northeru Slope ...... 74 +.iHatteras. N. C Y 51 11. 60 ye. ifi ...... South Atlant.ic ...... - 2 YiddleSlope ...... 68 -3 Ib...... "1 M S\V. 75 Y. Florida Peninsula...... 86 + 5 Southern Slope ...... 73 +7 Do ...... 31 58 11. Du...... 26 60 s. East Gulf...... 76 - 1 Southern Plateau ...... 58 +I2 Jacksonville. Fla ...... 20 51 s\v. Syracuse. N. Y...... 30 50 SW. 73 West Gulf ...... - 1 Middle Plateau...... 73 +3 hIuuut Tamalpaia, Cal.. . 28 62 IIW. Tatoosh Islaud, Wash.. . 5 50 9. Ohio Valley and Tennessee.. . 75 - 1 Northern Plateau ...... 86 +fi r10...... 30 69 IIW. Do ...... 19 52 *\v. Lower Lake...... 7Y + 1 North Pacific ...... $7 +1 1)o...... 31 54 11. IWJ ...... 24 62 9. 81 Upper Lake ...... - 1 MiddlePacific...... 71 -I0 Mount Weather, ..... 3 55 11W. Do ...... 25 60 S. North Dakota. 8? Vs ...... + 3 South Pacific ...... 61 -s Do...... 4 62 IIW. Do ...... 26 60 SB. Upper Miasissippi Valley.. ... 78 0 IKI...... 5 53 11W. no ...... 27 70 sw. - __ DESCRIPTION OF TABLES AND CHARTS. By Mr. WM. B. STOCKMAN,Chief, Division of Meteorological Records. For description of tables and charts see page 20 of REVIEWfor January, 1905.

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