(JANUARY, 1918. MONTHLY WEATHER REVIEW. 25
season of tornadoes in the Mississippi Valley extends from April to Se tember, inclusive.
estimation., WOUU be a. snjk place ?
Ana. The southwest portion of the cellar of a frame house. Q. Wh.t about cellars in. brick buildings during su.ch storms; m e the safe?
tornado. Some tornadoes merely destroy the roof of brick houses: some cause the walls to crumble or fall outward. The cellar of a brick house is probably safer than any other place in that particular structure. In the Omaha tornado of March, 1913, very few brick houses were seriously damaged.
Q. IVkd time o d q do these stoim occur ?
Q. Have there been any ad nighd? Ans. Yes. Q. Have the municipalities a.ny uwy of noi5jj)in.g th,e peo le and how?
E. The place where a tornado will form can not be foretold. Tornadoes, like thunderstorms nnd hail- storms, occur, for the most part, on warin, sultry aft.cr- noons, in the late spring and in summer. While the precise path of these storms can not be accurately fore- told, the weather maps show when the c,onditions are
favorable to their generation. The local signs of the approach of a tornado nre ominous clouds, first in the southwest and then almost immediately in the northwest and north. The a pear-
mce of a pendant funnel-shaped cloud may be taEen as conclusive evidence of the presence of a tornado. If a
funnel cloud can not be obsemed, its esistence can be known by a peculiar roaring noise, somewhat like the rumbling of distant thunder or the approach of a train of heavy cars. If one can see the tornado cloud and ain an idea of
line at right angles to the direction of motion. If the tornado is moving toward the northeast, then one should run toward the northwest., rovided, of course, the
servers position. The southern margin of a tornado is more dangerous than the northern, and one should take advantage of this fact in the endeavor to reach a place of safety, re- membering that usually the width of the path of great destruction does not cover more than B cou le of city
a short distance at right angles to the line of advance of the tornado.
Q. In case a y e F one eellur is not awrila.hlt, whd, in your
Ans. That x epends entirely on the severity of the
Am. Gener a i y from 3:30 to 5 p. m.
its direction of motion, then the zone o f safety is in a
storm is about to move a litt P e to the south of the ob-
Mocks and that comparative safety may be P ound only
DICTBBmATION OF OZONE AND NITEOQEN OXIDES IN SOUTEEEN INDIA2
By F. L. UBHEB and B. 8. RAO.
[~cprfntdfr~t~~ B~MICB AIM-, sect. A, oct. ai, 1917, iim.1
PITFALLS OF METEOBOLOQICAL PEBIODICITIES.
By W. W. B[EYANT].
[Reprfntal/rom Nature, London, Nov. 29,1917,100: 248-7.1
intelligible Englishahould be studied before much time
is s ent in the search.
8r. Ryd sets out clearly certain characteristics of meteorological data, wherein they differ essentially from e. g., astronomical data. One of these is tshe impossi- bilit of eliminatin some forms of systematic error,
tematic, such as the difference between the indications of a thermometer, under various conditions of exposure, and the real temperature of the air. Another is an error neither accidental nor systematic, but due to the fact t,hat the data are meteorological; a good example of this is afforded by the mean diurnal variation of air tempera- ture as shown on (a) overcast or (b) cloudless days. Dr. Ryd regards harmonic anal ais applied to such
worthy probe. The known periods-the day and the year-are unexceptionable, and the variation from hoiir to hour in one case, and from da to day, or preferably
fit subjects for analysis. Dr. R d prefer; to use b o d
tion, because the determination of mean error is more direct when two constants enter similar1 . This is
tion. Analysis for testing n real period, such as one of the lunar periods, on the meteorological data IS not uite so risky as tentative fishing for an unknown perio!, in
Computation cd Meteorological O b s e r v a t l o m ~Y . If. R f i (Copt&qpn, 1911).
whit 5 are too likey k to be variable to be strictly sys-
data as an excellent interpreter, z ut a very untrust-
from pentad to pentad, in t i e other, are obvious1
sine and cosine terms instead o P the usual transforma-
clearly important, ns the mean error is a vita T considera-
1 PubUkather Ira Det Danske Meteor01 e Inatltut Meddelelser. No. 8, On
26 MONTHLY WEATHER REVIEW. JANUARY, 1918
which case at least one coefficient, according to Dr. Ryd, must be five times its probable error before it can be
%e brochure is divided into two sections, the h t dealing generally with such routine roblems as the com-
of obervational data, and harmonic analysis, with an additional chapter on secondmy minima and mmima in the annual variation of the temperature, in which the author deals with the proverbial Ice-men of May 11,
12, and 13, and esposes the weakness of Doves supposed proof of the reality of this legenda xg phenomenon. The second part deals fully with mec nnical adjustment, factors of variation, and suggestions on the choice of formula?, of which several are given, and s
concrete examples, viz, the hourly inequality of air tem- erature, Greenwich, 1849 t.0 1868; and of pressure, &xmwich, 1854 to 1873; Lhe annual inequality of pres- sure, Batavia, 1576 to 1905; and the annual variation of t.emperature, Copenhagen, 1875 to 1910, the last being a
w e of partial data-only three observations at fised hours of the day, instead of the full set. Dr. Ryd reminds the reader that when data such as
July air temperature for 20 years are entered in rows for days and in columns for years, they can not be analyzed similarly in both directions, inasmuch as the successive days are not independent, while the columns are. He also discusses at some length the order to which har- monic analysis , if used for adustment, should be pushed, with hints for savin labor; but on the whole he prefers
the majority of cases, ancl thinks this method less liable to introduce new errors into a problem.
arded as likely to be real.
putation of the mean error, smoot 1 ing and adjustment
longer adjutin% c apter is devoted to the workmng out of four
the mechanical a f justmen! with a suitable formula in
BELATXON BETWEEN BAROMETBIC PBESSURE AND THE WATER LEVEL IN A WELL AT n W OBSEBVATOBY.
By E. G. BILEAM.
[P m t e d to the Royal Society, Ladon, Nov. IS, 1811.1
(Rcprillrad fmm Nature, London, Nov. 22,1917,100: 289.)
The water level shorn a well-marked response to changes of barometric pressure at all tunes of the year. Under similar conditions a iven increase of pressure,
b, which is proportional to 8 . The vaue of &u/6p
ne ative. The validity of the equation wm es- ta % lished between limits given by dp/dt > 0.5 mb./lw., and the value of a was determined in the case of three ou s of months representing hi h, intermediate, and
pressure was found to increase rapidly with the height of the water, the value of a for a height of 360 cm. above mean sealevel being four times as great as for a height of
200 cm. The change of sensitiveness. appears to be entirely due to the change in the condltion of the soil. The average value of a is 1.1 mm./mb. There appears to
be no la in the res onse of !he well to changes of pressure,
tions of pressure are shown on the water leve trace.
9
8p, will depress the water leve 5 in the well b an amount
varies with the mean level of t 1 e water, but is always
ffw Pevels. The sensitiveness o P the water level to
P
and un cf er favora I? le condltions the most ra id fluctua-
In the original of this paper Mr. Bilham has worked out in mathematical detag careful observations. similar to the more eneral ones dlscussed by the undersigned in the REVIEW Q or February, 1916, p. 75-76.-c. A., lr.
PHENOMENA CONNECTED WITH TURBULENCE IN THE LOWER ATMOSPIIEBE.
By G. I. TAYLOR.
[Presented to the Royal Sodety, London, Nov. lS,1817.]
(Reprintedfrorn Nature., London, Nov. 22,1917, IW: 239.)
In a previous paper by the author it was shown theo- retically that a connection should exist between the rate at which heat is conveyed into the atmosphere by means of eddies, and the amount of retardation of the velocity of the lower layers of the atmosphere behind the gradient velocity due to the friction of the ground. In the present aper the amount of the turbulence over Paris is calcu- fated from tem erature observations taken on the Eiffel Tower. It is s R own that the amount is the same as that calculated from observations of the change in direction of the wind between the bottom and to of the Eiffel Tower due to the friction of the ground. $he daily variation in wind velocity which depends on the daily variation in turbulence is nest discussed, and it is shown that the chief characteristics of the observed phenomena of daily variation are explained, both ualitatively and, so far as is possible, quantitatively by t l l e authors equations.
SWISS SOCIETY OF GEOPHYSICS, METEOBOLOGY, AND ASTBONOMY
Under M. Mercanton of Lausanne, as chairman, a circle of the more active Swiss physicists , meteorologists , and astronomers assembled in the great physics lecture room of the University of Berxie on A nl 28, 1917, to organize the society of the above name &oci6t6 Suisse de GBophysique, MbtBorologie et Astronomie) and adopt statutes in conformity w t h ib proposed activities as a section of the Helvetian Society of Natural Sciences (SociBtt.5 helvbtique des Sciences naturelles). The fol- lowing officers were elected for 1917-1919: President, Prof. Dr. P.-L. Mercanton, of Lausanne; vice-president, Prof. Dr. A. de Quervain, of Zurich; secretary-treasurer, Prof. A. Kreis of Coire. The first regular general meeting of the society was held September, 11,1917, a t Zurich, with an attendance of 34, out of 70 members already enrolled. The assem- blage was welcomed, in the name of the Helvetian Society of Natural Sciences, by Dr. J. Maurer, Director of the Federal Meteorological Bureau, who congratulated the young society on the lively interest already awakened for it, and then retired in favor of the president, M. Mercanton. After some discussion, the society unanimously ado ted the roposal by P. Ditisheim (La Cham-de-Fond$, a notes Swiss horolo ist, that the Federal Council be re-
%e day, 1 to 24. This is a conscious renewal of the ma- jority recommendation of the International Prime Me- ridian and Time Congress of Washin ton (18841, but
ment. The system has been in use on the Indian railwa
introduced into Italy in 1893 with the adoption of Central Euro ean Time, was approved in 1895 at the London
(fifthp session of the International Railway Congress, was adopted in Belgium in 1897, and put into practm by the Bureau des Longitudes (Paris) in all its publications in 1900; has been used by the French railways since July 1,
-
uested to adopt t f e serial numeration of the hours of
would be only a rather tardy step for t!i e Swiss Govern-
since 1859, waslegalized forCanada in 1591,? wasactu 2 y
1 Compte rendu des Seances de la 90ciBt6 Sui= de a&pb hue M&4orologle et Astronomic (a. M. A.) In Archlvas dcs scl. php. et nat., I& &, 4 h e pk., Q& 15 nov. 1917 44: 845 hi.
2 Thisystem has b n in &tuel USB on the C. P. railway west or Wldpeg for Anany
mn.