MARCH,1916. ,:/.; '/A- ) MONTHLY WEATHER REVIEW. 123 .. 1.I .. . e.,$, J WFALL D~TAOF~~BXLEY, cu.1 vatory shows no break in continuit when the position of the gage was changed in 1592 an in 1899. By WILLIAMGARDNER REED. B [Author's abstract, Wsshmgton, D. C., Mar. 10,1910.1 TABLE2.-Sumnucry of rar'nfnfnll data, Bakely, cal., July, 1887-Juire, 1915. Engineers are of necessity payin more and iiiore at- (Compiled from ohsermtions hy the Unlverslty of California In maperation with the tention to rainfall dat.a, particularK y to data of heavy 8. Weather I3ureau.] falls of rain in short intervals of time, because of the U. importance of a knowledge of such heavy falls in con- Total precipitation. Number ofdays wlth 0.01"~more. nection with t,he designing of storni scwers and ot.her I structures which must carry off the rain wat.er. The I.enrt. Greatest. records kept by the University of C'alifornia as a co- Month. - -

operative station of the Weather Bureau since 1886, sild c ai - :I, -by the sanitary engineer and the department, of civil p- - E +5 e ineering of t.he university since 1910, have been s i. 4 taT ulat.ed and studied. These data are the only records - -- ... ._ . ______la. lays. Pap. Days. available for the east shore of San Francis!co Bay, and Jnnuary.. __. I. 7s IS89 12 -5 1909 4 1889 the study is of interest because it modifies nnd estends Febrinry.. .. 1. "'2 lSY9 9 25 1915 1 1898 the previous March...... 4.59 13.19 1H9 3.31 189s 1u Measurements of preci itation, using .z standard 8-inch rain age, have been ma e at least once each day since -\pril...... 1.63 0.73 lS9G I. 02 1909 6 14 1896 t; 3Iav...... 1.27 3.63 1805 0 1909 5 Octo% er, 1886. Until 1S9'3 me~urenientswere inade Julie ...... 0.21 1.24 1907 0 8yrs. 1 regularly at '3 p. 111. (Pacific time) ;since IS93 the iiieasure- July ...... 0.02 0.44 1891 0 18 yrs. 0 0 Uyrs. ments have been made at 8 a. ni. and 8 p. m. Mensure- August...... 0.04 18913 ments have frequently been niade at the end of t.lie rain 0.90 0 14 yrs. 0 2 0 myn. and during rain, although the practice has varied froni Scptrmher.. . :I 5. s 4.44 1904 0 6grs. 2 the to time. Since 1910 records froni a Fries tipping- October. 11RR7 .... 1.43 5.80 1889 0 1 1890 4 0 lyrs. bucket gage, elect!ricdy recording, are arailahle : but. 1680 these records are more or less fragnient,ary because of Xo\.cmher.. . 2. Gs 5.89 l!W3 0 lS90 7 1913 1 { 18071894 a e failure. The exposures of the gages are shown by DeCCinlm. .. 4. :9 12.13 lS94 1. p" 1898 1u !%%le 1. Scar (July. June!.. .. !a 72 :4fi. uo I IM9-9 1. .w lS!37-%S 6li 104 1599-90 52 1897-98 TABLE1 .-Raingage ecpoazcrea at Berkeley, C'd3 - - I II 8dnch &gage. TABLE3.--.tiri.i-iniiini prtvipitntiori .in I duy for each rdnfnll year, July, 1.3fC-Junr. 1915, Brrkeley, C'al. Date. Descrlptim ofexposure. H. h. Readat- I I 1 I [Compiled from ohnervatinns by the Univc-rsity of California in cooperation wlth the I;. 8. Weather Bureau.] F/. FI. Pae. Sf. T. October 1858 to Sep Framework over a rtion of the 317 21 2p. m. tembe;, Id. observatory huil&. Rauifall year. Amount. Yonlh. I( Rainfall year. I Amount. 1 Month. Be mber 1892 to On the mndnorth of obseffs- Pa. in. f$temh;r 1SSe: tory build-. } 3% 1 {ip. m. sheSeptenlber, 1899.. RWIbuilding. of extension of oberwtory }334 Ischrs. Inchrs. 15 c;:R 158;-SS ...... 1.94 January. 19Ul-E ...... 1.79 February. ISSW...... 3.43 March. 19~243...... 2.01 November 1s9-90 ...... 3.a January. 190344...... *4.75 February. 1sw-91 ...... 4.10 Fehriutry. 1904-4~3...... 2.75 September. 1s91-92 ...... 1.56 DecmlJcr., 190:FoI...... 1.78 March.

~~ 1892-93...... 2. gG December. 190107...... 2.31 March. Slnce January, 1911..... Roof 01 8 feet x 12 Ieet shed 12 70 Electric8 11V 18%-94 ...... 3.70 Janmry. 190748...... 1.85 January. feet above roof of civil engineer- record ink 1594-95 ...... 2.20 January. 1908-09 2 34 Januar inp bullding, 60 Ieet square. each 0.01 ...... inch rain. 1895-96...... 2.48 ?\prIl. 1939-10 ...... 1:tX DecemLr. i 410 I I 18M...... 2.31 Noveinher. 1910-11...... 2.88 January. 18974...... 2.19 ...... 189S4l...... 3.w ...... Although roof es osure is not to be recommended, 1899-00 ...... 3.22 ...... conditions at BerkeP ey have made such esposure neces- 1~1._.______.__._2.06 ...... sary and this es osure is fairly A careful *This amount Iell between 1 p. m. Peh. 11, 19U4, and 3:45 p. m. Feh. 12, 1904; the examination of t E e rainfall record of the Students' Obser- 24hour amount is uot available.

1 A revised summa by the author of the material contained in the following papers: TABLE-t.--Ma~imwni preri1ntntio.n .in 1 clny.for en& monU, Berkely, Cal. Rainfall datn of Bexeley Cal 1Tniv. Cal. ubl. in au in 1 69-81. Berkelev 1915 Rainlall data of Berkdei, Ci., 11. UnIv.%al. publ. !I$gi:n., I: 83-118. Bb;keley; IOlli [Based on records July, lPS'I-June, 19!5. compiled from ohserrations by the Unlversity of California moperation with the 8. Weather Bureau.] 1 The prhd3.al~pere dealing with heav Ialls of rain for the region are 8s follow: in U. BruMky C. . he sewer system of an Prancisco and a solution of the storm-water Itow rohlem Trans Am sw c e NewYork lgbg 65.- 294-423. E& C B' Repod on iUcbin&i' Cal sew& 1WO. M~th. IAmount.1 I'ear. )I Month. I Amount LC &.ti i. J. hteneity 01 rdllai'san F&C~SCO C~I.T~s.. Am. sor. c. e., New York' 1905 W 197-198, in disrusslan of C. W. ShPrman, Maximum rates of rainiall at Boat&. Inchrs. Inck.4. Meddle, A. G. The ralnfall of Callfornia. I'niv. Cal. publ. geog., Berkeley, 1914, January...... 3.70 July...... 0.44 1891 I: la7-240. February...... *4. 75 August ...... 0.84 1898 McAdIc. A. G. The climate of 8an Franclwo, Cal. Washington, 1915. 6'. (Ir.8. March...... 3.43 September...... 1.76 1904 Weather Bureau. Bul. 44.) Ap...... 2.45 October...... 3.22 1899 :The exposures are discussed at length in "Rainfall of Rerkeley Cal. '' Univ Cal ay ...... 2.16 November...... 2.41 1903 rk! fog. Berkeley, 1913, I:133-79. Report of the meteorologic~lstation. 19i2-13: June ...... 0.62 December...... 2.96 1692 erkdey, 1914, 1:247308. Report, 1913-14. ibid., Berkeley, 1916 I :373-439. 4 Matoln C. F. The measurement of reripitation. U. S. Weather Bur. Instrument Dlv. Circuiar "E," 36 edition, p. 15. $dington, 1913. * bfaximum In one day, 4.75 h&CS February, 1904.

Unauthenticated | Downloaded 09/25/21 05:45 PM UTC 124 MONTHLY WEATHER REVIEW. MARCH,1916 TABLE5.-Precipitah oj2.50 inches or mein 24 hours at Berkeley, TABLE6.-Precipitation of marked iiitcn8ity at Berkelq, Cal., Jan. 1. Cal., July, 1887-June, 1915. 1911, to Apr. 80. 1915-Gontinued. [Complled from observations b the V‘niversit of Californh In cooperation with the - 5.5. Weather 8ureau.l 5-minutc 1-hOUI Total rsin in 12 hours. period. ariod. Month. Year. hount . I- - 1% hour period ending at- Maxi- Ratio Maxi- Come.- mum l- Inches. mum spond- total Beptember...... 1904 2.75 Obs.* C. E.* C.E.+ total inpin- October...... 1S99 a. 22 Ob. rain November...... None. rain. tensity md in- December...... lS92 2.96 ensity. January...... lS90 8.63 -- -- - Do...... 1894 3.70 Do...... 1911 2.88 In per In pm February...... 1891 4.16 1914. In. In. In. hi. hr. Do...... 19ln 4.75 Jan. 2,83. ni ...... 0.99 ...... March...... 1889 3.43 Jan. 12.Sp. m ...... 2.01 2.w 1.0. 0.M 0.96 0. sa Do...... 1898 3.20 Jan. 14,5n. m ...... 0.72 0.61 U.65 0.06 0.80 U. 31 Do...... 1904 2.91 Jan. 17,sa. m ...... 1.02 ...... Jan. 17,Sp.m ...... 0.57 ...... 0.07 0.84 0. 81 J8U. 22,Sa. m ...... 1.16 1.05 0.90 0. 88 Jan. 24,811. m ...... 1.32 1.05 0.80 ::: ::g 0.8 From a statistical and gra hic study of all 12-hour Fcb. 20,Sp. m...... 1.15 1.06 0.92 0.06 0.80 0. I eriods for which records o!l? intensity are available Mnr.29.Sa. m...... 0.82 0.90 1. io 0.10 1.24 0.4 Prom the recording gage, the following have been deduced: Apr.4,Sa.m ...... 0.49 0.3s 0.93 0.M 0.7.9 0.32 0.89 0.97 0.08 0.78 n. 33 (a) When 0.80 inch falls in 12 hours, there is a chance 0.#6 1.00 0.10 1.20 0.58 that the maximum intensity for 1 hour escmds 0.50 1.20 O.L% 0.05 0.80 0.43 inch. 1915. (b) 0.SO 19 Jm.6.8a.m ...... 0.65 0.68 0.86 n.m 1.s 0. I When inch falls in hours, it is probable Jan. %Sa. m ...... 0.Si 0.82 0.94 U.13 1.56 o. 52 that 0.30 inch for 1 hour has teen exceeded; this is 0.4s 1.05 0.03 0.36 0. 30

~~half the maximum shown bv.I the Grunskv curve for Sail Feb.2,Sa.m ...... o.S 0.74 0.89 0.n7 0.a 0. $1 1.) Feb.7.8p.m ...... 1.06 0.96 0.91 0.06 0.80 0.31 Francisco. (See fig. Feb.16.Sp.m ...... 0.83 0.bi 0.82 0.17 2.04 0.31 (c) When 0.80 inch falls in 13 hoursJ there is a chance: Feb.22.Sp.m ...... 0.99 ...... Feb. 24. Sa. m ...... 0.3s 0.94 0.0s 0.98 0. y that 0.15 inch in 5 minutes has been esceeded;. this is hpr.26.Sa. m ...... ::3 0.34 1.M 0.10 1.20 as the maximum shown By the Grunsky curve. I (d) When 0.80 inch falls in 12 houi-s, it is robable that 0.07 inch in 5 minuFs has been exceedel; this is Table 6 is a sumnirtry of the data of heavy rainfall- the lower limit of practical importance; it is half the from which the study was made to determine the occurs maximum shown the Grunsky curve; rence of precipitation of marked intensity. It includes by all 12-hour periods from , 1911, to April 30, TABLEB.-Preapitation of marked intensity at Berkeley, Cd., Jan. 1, 1915, durin which the amount indicated important 1911, to dpr. 30, 1915. intensities. %&muting intensities for Berkeley are: ~~~ - 0.80 inch in 13 hours. Total rain in 12 hours. bmiuute 1-hour 5- period. period. 0.30 inch in 1 hour. - - - t- Mnri- > 0.07 inch in 5 minutes. l%hour period ending nt- Maxi- Come mum Ratio mum ;pond- total The table indicates that the 5-minute or 1-hour periods Ob%* ‘. E.* ?.E.+ total ingiu- rain with precipitation of ap rosimatel half the maximum Obu. rain. ensity. and in- tensity. intensity will occur at gerkeley a out as often as the - 12-hour amount equals or exceeds 0.80 inch. -I- -I- A study of the records of heavy continuous down ours 1911. In. In. In. has made it possible to estimate with a moderate epee JW. la 8a.m...... 0.98 ...... a Jan 13’ 8p.m ...... 0. s 0. M 0.98 0.13 1.56 0.15 of accuracy the probabilities of the masinium intensity Jan’ 14’ 8a.m...... a. 00 1.96 0.98 0.03 0.7.9 0.39 JS~:ao’ 8a.m ...... 1.76 1.69 0. I 0.05 0.60 0.35 when we know the total fall of rain and the duration of the Jan. 24’ 8a.m...... 1.42 1.43 1.01 0.05 0.611 . 0.30 downpour. The results are given in Table Jan. 24’ 8p.m ...... 0.82 0.74 0.90 0.04 0.4s. 0.36 7. Jan 18’ Bam...... 1.27 1.18 0. 93 0.06 0.60 0.33 Jan: 29’ 8a.m ...... 1.03 0.91 0.88 0.06 0.60 0.10 TABLE7.-Ralio of aeeralye intensity to mnrcimm inteidyfor shwt periods Jan. 30: 8a.m:...... 0.78 0.66 0.53 0.09 1.w 0.32 of heavy continuous downpour, Berkeley, Cal.. Januuy, 1911, to Feb- Mar.( Sam,...... 0.86 0.57 0.88 0.09 1.m 0.33 ruary, 1915. ~1sr.6’8p.m...... 1.13 ...... 0.06 0.72 u.4ti ~sr.7’~a.m...... 1.14 1.23 1.08 0.29 3.4s 0.51 ~..66:sa.m...... 1.45 24 hrs ...... conthuous downpour. inten- Ratio: madurn+ I I Sltty. average intensity. 1912. Jan.% 8a.m ...... 0.17 0. YJ 0.95 0.10 1. ?I) u.3s I ~sr.l!i,8a. m ...... 1.02 aw 0.94 o. 04 0.48 I 0.26 10,8p. m ...... 0.41 0.91 0.09 1.1s 0.18 Tqtal Dura/Average 5min- lOmin- Smin- 10mln- ir.yza,sp.m ...... :: 3 0.08 0.67 0. 08 0.9ti I u.m I ram. I tim. :htensityj Utes. 1 Utes. I Utes. I utas. Nov.6 Sa. m ...... 1.44 1. a5 0.8% 0. as ~W.6’8p.m...... 0.95 0.85 0. Si 0.04 ~ec.11,~p.m...... 0.60 0.4s u. 9s u. 10 1913. an. 8.88 m ...... 0.68 0.66 0.05 0. as 0.96 0.3u an. 16 p. m ...... 0.41 0.95 0. 85 0.0s 0.96 0.33 Mar. d,Sp. 1...... 0.6.8 0. .(e 0.94 0.09 1.6 0.20 1 Jan. 12,1914. *Jan. 23,1912. 1 Mar. 7,1911. Nw.18,Bp.m ...... 0. s9 0.78 0.85 0.06 0.80 0.33 NW.20 88. m ...... 0.68 0.67 0.97 0. 08 0.96 0.35 In the consideration of the run-off of rainfall of marked ~~.d~a.m...... 1. 00 ...... ~ec.~,’~a.m...... 0.82 ...... intensity, the condition of the ground at the time of Deo.30,Sp.m ...... 1.54 ...... 0. OB 0.78 0.33 maximum intensit is important. At Berkeley frozen Dec.31.8p.m ...... 1.14 0. s5 0.75 Lo7 0. s4 0.9: ground does not deot the problem, but the amount and * Ob.-%inchp at Students’ Observ?tory. C. E.-J!&inc gage, electricslly recordmg, at Civil Engineertng Building. duration of rainfall immediately preceding the maximum

Unauthenticated | Downloaded 09/25/21 05:45 PM UTC ~CH,1916. MONTHLY WE-QTHER REVIEW. 1% intensity are of considerable importance.b These data TABLElO.-Percentage of mea at Berkeley, Cal., 1911-1915, in which Ps are presented in Tables 8, 9, 10, and 12. maxinmm intensity of rainjall for 1 hour occurred within a given p&d fmithe beginniw of the starni.

Maximum inmsity for 1 houroccurned within- Per cent of cases. TABLE8.-Percentage ves at Berkeley, Cal., 1911-1915, which the l- of in 1 hour from the heginning of the storm...... a0 mazimum intensity of raanfall fur 5 minutes oecurred within a given 2hours do. do...... 32 period from the beginniTig of continuous heavy rniii. 3hours do. do...... 36 4 hours do. do...... 38 5hours do. do...... 44 Maximum intensity for 5 minutes occurred within- Per cent 6 hours do. do...... 47 of cases. 12 hours do. do...... 58 18hours do. do...... 67 24 hours do. do...... 76 5 minutes from the beglnnlng of heavy raln ...... 2Q 30hours do. do...... 82. 10 minutes do. do...... 40 a0 minutes do. do...... 52 36hours do. do...... 88 80 minutes do. do...... 01 42hours do. 40 minutes do. do...... G3 48hours do. %hours do. Bo minutes do. do...... 06 BOhours do. Po minutes~..- do. do...... 77 la0 mnutes do. do...... 86 72 hours do. do...... 98 180 minutes do. do...... IOShoura do. do...... 100 24Ominutes . do. do...... ____~__. 900 minutes do. do...... 97 360 minutes do. do...... 110 minutes do. do...... d80minutes ’ do. do...... 100

Maximum intensity for 1 after a fall of- Per cant hour I ofoases. 3.00 inches or less...... 100 2.50 do. do...... 94 TABLE9.-Percentage o cases at Berkely, Cal., 1511-1515, which the in 2.00 inches or less...... 00 maximum intensity ohainfall for 5 mimtes was preeedzd by e01it~iituou.s 1.N do. do...... 88 rain for a given amount. 1.60 do. do...... &I 1.40 do. do ...... 82 1.3 do. do...... 77 Per cent Maximum intenslty for 5 minutes occurred alter a fall of- 1.110inc-h or less...... n of C9sM. 0.W do. do...... 70

~~ ~ 0.80 do. do...... 88 0.70 do. do...... e5 1.80inchssoriess...... 100 0.dU do. do...... 61 1.00 lnch or less...... 99 0.80 lnch or less...... Yti 0.50 inch or less...... 55 0.40 inch or less...... n...... YS 0.40 do. do...... 51 0.30 inch or less...... 81 13.30 do. do...... 46 0.20 inch or less...... 81 0.20 do. do...... 34 0.10 Inch or less...... ti0 0.10 do. do...... -25

TABLEI2.-Compa&m of intmities of rminfall obtained from vnrioiis curves for Snn FranriSro mzd vi~m?jand observed mariniuin at Berkeley, CaL - Intensities in inches per hour for periods ol- Refer- BllcB Formula. No. 5mln. 10min. 15min. 20min. 3Omin. 45min. 1 hr. 11 hrs. 1 zhrs. 3hrs. 4hrs. 5hrs. lob.

------~ ------

1 b3.08+[x ...... 1.79 1.31 1.10 0.9; 0.81 0.08 0.GO 0.51 0.45 0.38 0.34 0.32 0.Z l+Go+to .]‘ None ...... 2.1~ 1.50 1.30 1.02 0.83 0.6s 0.m 0.51 0.45 0.38 0.34 0.32 o.~ b7l-W...... 3.14 2.21 1.81 1.57 1.Z 1.05 0.91 0.74 0.M 0.52 0.45 0.41 0.28 i35+t04 ...... 2.24 1.5s 1.29 1.13 0.91 0.75 0.d5 0.53 0.46 0.37 0.32 0.28 0.20 5 None ...... 2.W 2.00 1.G5 1.41 1.12 0.88 0.74 0.8 0.51 ...... 0 None ...... 3.4s 2.01) 1.G5 1.11 1.12 0.88 0.74 0.M 0.51 ......

7 ~ i-5.25+[to~~-O.7 ...... 3.52 2.18 1.68 1.41 1.11 0.88 0.75 0.60 0.52 0.39 0.36 0.32 0.24 8 Automaticrecor?%.:::::: ...... 3.18 2.00 ...... 1.41 1.10 ...... 0.74 ...... 0.43 ......

1 ffrunskv C. B in Trans. Am. soc. e. e. 19W 65,318. Data from all sources for 8an Francisco before 1899. a’ (3nmsky’ C. E” in Trans ’ Am. so?. c. e ’ 1908’ 65,310. Data from U.5. W.B. 119-19W. 3: Lr CmtC L. j.: in Trans:: Am. so?. e. e:: 1905’ 54,198. Data from Thomas Tehent and U. S.’ Weather Bureau, Sari Franciwa, 1S50-1903. 4 Metcalf 8 Eddy in American Sewera Practice, v. 1.1914 p. 23q. 5’ Hudr C ff in he ort on Richmond Ewers 1910. Data trom City Engineer Oakland 1fW.W. 0: Whit;, if. it., in ‘‘%lalnfnll data of Berlieley:Cal., 11, by W. C:. Reed and M. t. White.:’ Univ. Cal. pubi. eugin., Berkeley, 1916,l: S11G. Data from the mxordiq &age at the university 1911-1915. 7 Whiff k.K in Mathematical form of No. 0. 8: Tipp&-bnc& gage record at Berkelcy, 1911-1915.

b Hen A J &all 01 the , United States Weather Bureau Bull. D (Washington, 1897), p. 53, also published in Annual Report of the Chlef of the Weather Buresu 1ki7(kashii 1887) g363. Cor;espondence from A. J:Hcxu; Journ. Western Soc. Engrs vol. 4 (Chicago, lW), pp. 1G-166, in discussion (pp. 147-1W) of E. Duruca, jr., “Tables of excesdveprecfpi- tations of rain at Chicago, Ill. from 1889 to 1887, inclusive,” pp. 53-1Oi: Netcalf and Ed&, Amerfcan sewerage practice, vol. 1, p. 21%.

Unauthenticated | Downloaded 09/25/21 05:45 PM UTC MONTHLY WEATHER REVIEW. MAEOH,1916

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TIME (t)IN MINUTES Figure 1. a8 FI~URE2. Probable oecumnce of heavy rainfall at Berkeley, Cal. Based on record of recording gage, Civil Engineering building, ,1911, to April 30,1915.

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Unauthenticated | Downloaded 09/25/21 05:45 PM UTC MARCH,1916. MONTHLY WEATHER REVIEW. 127 Table 12 is a comparison of rainfall intensities, indi- of curvature of the axial line of Honshu, the lines of cated by the various curves which have been used in the e ual rainfall ex ectation have a tendency to run par- design of structures to carry off storni water in the San as el to the asial Pine. In this case the draining influence Francisco Bay region, and also the recorded masiniuiu of the coastal mountaiu ranges becomes obvious, in giving intensities for the five gems during which the tipping- birth to a comparatively rainless zone in the axial region bucket gage has been in operation at 13erkeley. The of Honshu. curves are shown b figure 1. For tlie case of the center lying over the Pacific, the Under some con&tions it might be unjustifiable to de- rainfall is rather concentrated 011 a limited region of more sign a structure for the absolute maximum storm; but if or less closed shape. the design is made for a storm of less severity,.it is well to (3) Coin aring the depressions lying over the sea but how how often the structure is likely to be made uate. not very Par from the coast, the Pacific depression is For this reason figure 2 was drawn from the data 1or all associated with a more dense and extended precipitation stornis in which marked intensities were reached. In area on the land than the Japan Sea one. order to draw the curves it was necessary to make some (4) When the depression lies east of Sakhalin the entire interpolations for storms for which the intensity records Japan Sea coast is ttffected, and the lies of equal expecta- are incomplete. The curves show within tlie limits of tion run parallel to the land. error im osed by the interpolation and tlie rather short In connection with these investigations a general record (l ve years) what intensities may be espected in theoretical discussion of the problem was attempted. the intervals shown. It seems convenient to analyze the secondary influences causing the ulls inmetrical distribution of cyclonic pre- cipitation into tie followin three principal moments: DISTRIBUTION OF CYCLONIC PRECIPITATION.’ (a) Planetary thermal in8 uence, which consists in the c.hange of temperature with latitude. This influence re- By TORAHIKOTERADA, Rigakuhakushi. sults m shifting the center of rainfall on the southeastern [Dated: Phystesl Institute of College of Science, Tokyo Imperial Irniversity, Nov. 20, side of the center of de ression, in the Northern Hemi- 1915.1 sphere, provided the otR er conditions are uniforni. [Author’s abstract.] (a) Geographical thermal influence, which consists in The regional distribution of cyclonic rainfall has already the thermal contrast between land and water. The re- been investi ated b many meteorologist^.^ The results, sults differ widely according to the season, and also ctccord- however, diBB er wi ely accordin to the localities con- ing to the humidity of the land in uestion. For esam- cerned, and as yet no general tieoretical7 discussion of ple, in sumnier in tlie Northern dernisphere, provided the principal niomentv determining the distribution in the land is sufficiently humid, this effect taken &ne will question seems to have been attemqted. tend to increase the precipitation on tliat side of the de- Recent1 Messrs. T. Yokota and 5. Qtuki, undergraclu- pression which looked at from the center has the land ates in de Pliysical Institute of tlie Science college, 011 the right-hand side. undertook tlie statistical iuvestigation of tlie (c) H$rodynamicnI to ographical influence, which regarding Japan. Tlie cliief data used were consists ni the forced asceii!ing air current brought about weather charts of the Central Meteorological Observa- by the discontinuity of the horizontal flu of air at the tory from Januafy, 1905, to December, 1915. Tlie main boundary of two regious with diflerent coefficients of islands constitutmg Japan pro er, i. e.! Kiushu, Shikoku, friction.3 According to this influence, the preci itation Honshu, and Hokushu, were t;ivided into 18 districts, 6 will be generally abundant, csteris paribus, on $at art each for the Pacific, the Japan Sea, and the axial region. of the coast line, or that side of a mountain range, w ich The percentage expectation of preci itation for each of viewed from the center of a cyclone has the sea or low- these districts was calculated for diP erent possible posi- lands on the right-hand side. The direction of the eat- tions of the center of a cyclone. Tlie chief results est rainfall depends on the difference of friction. These obtained may be summed up as follows: relations have been fully discussed in the paper above (1) In front, i. e., on the northeast side of a cyclone, cited? the preci itation is generally more frequent on the Pacific These three influences combined roperly seem to ex- side of tie land than on the Japan Sea side. OU the plain the peculiarities of rainfall 8istribution in most P diverse cases. For exam le, result (1) above mentioned rear side of the barometric depression tlie reverse is the is the direct outcome o the third influence (e). The case. The difference is most pronounced in regions P remote from the center. result (2) may be ex Iained if we consider that the amount of the third in;P uence (c) niainl depends on the (2) When the center of tlie depression lies over the angle made by the coast line with e radius vector Japan Sea far from tlie land, specially if near the center tz -~ ~- .- drawn from the center of the cyclone toward the point 1 Tszrdo Tomhiko. On the distribution of the cyclonic preri itatims. (An ab- concerned. Besides, the draining effect of -the mountain stract [had Nov. a0, 1915.1 Proc.. Tbkyb mth-phys. SOL, 1& (Z), 8, no. 12, pp. S2-d Also se arately prmted. range may also be iuterpreted in terms of the same in- [Thespelling of lace nfamea conforms to the decisions of the TT. . 8. Board on Geographic fluence, smce on the lee side of the range a downward ~m.4.A. jrj‘ 1 Hildebrandaam €I.Sur la distribution des Bl6mmts rn4t8orologiquks nutour des velocity is superposed on the general upward velocity minimas et des dximas larorn4tri ues. I~ppsala. 1883. of air proper to the inner re ion of cyclone. van Bein Yeteorol. Ztsck I& a fkerMom PI Sur las distrib&m e’ Vienne et & Torsham des Bldments, etc. Again, result (3) may be eucidated by the combina- grank&en.in Yeteord. Ztsciu., IN. f Polis in Yeteorol. Ztschr., 1W1. tion of influences (a)and (c), since in our case the supply D ky in Meteor01 Ztschr 1903 of the moisture precipitated is mostly from the ma (the in mom+ met. iiag im. 39- Quart. jour., ~oy.met. am., iem, 36. MT#‘% ~~ uu i. 1. in imoria's met. mG.,1~,4i. Bed ~TR.d in ~O~HLYWEATHER REVIEW Oct 1911 39: 1609-10. In the BBWof the generalized Quldberg & Yohn theory. 8ee T. Tcroda, Q Roo. Ha& J. &be der Bhteorologie. 3. Aufl.: 191;; p. h4,552. T6ky6 math.-phya. &., 1914, 7. 40218-16-2

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