205 lines
10 KiB
Plaintext
205 lines
10 KiB
Plaintext
68
|
|
|
|
MONTHLY WEATHER REVIEW.
|
|
|
|
FEBRUAR1Y9,16
|
|
|
|
The wind direction during and immediately following planation is untenable, for no regions have been discov-
|
|
|
|
the observation of a ha.10 seems to play an im ortant part ered presentsing the phenomenon of 'a continual return
|
|
|
|
in its verification as a rain pro$ostic. Of tEe 168 halos current, and apart froni this fact, the esistence of a cir-
|
|
|
|
recorded, 94 were :Lttendecl or ollowed hp etisterly winds culation of the kind depicted would necessitate that the
|
|
|
|
and falling pressure. Of these, 82, or 87 per cent, were electromotive forces a.round closed paths, in which the
|
|
|
|
followed by precipitation within 48 hours. This result,is flow was taking place, would have to be of the order of
|
|
|
|
E Y im ortnnt, in view of the fact that of the total number magnitude of 105 volts. F:Zeetrostnt.ic forces can contri-
|
|
|
|
of alos recorded, but 99, or 59 per cent, were followed by bute nothing whatever to u line inte a1 around a closed
|
|
|
|
rain or snow within 48 hours.
|
|
|
|
circuit. A consideration of such va ues of the line inte-
|
|
|
|
Un;timcaZ &:.is )Imp, Fort Worth, Tex.--Cninples halos gral as could be obtained on the basis of the change of
|
|
. are rare inclee(f. Even the 46'-hdo ocmrs but infre- magnetic induction due to the earth's magnetic field From the time angular measurements were through a closed circuit, or of the motion of the earth
|
|
|
|
r rstt lmyade at this station, seven 46"-htilos litwe been re- and atmosphere in the magnetic lines of forceof the earth
|
|
|
|
corded. On the evening of May 23, 1901, two parhelia shows that, apart from the circiinistance that they would
|
|
|
|
were noted as the sun was about IOo above the western he of n nature unsuitable to correspond to the facts, they
|
|
|
|
horizon. They a peared on the edge of u bank of alto- would be of an order of magnitude entirely too small to
|
|
|
|
stratus clouds. 8etwcen this edge and the horizon the play any appreciable art in the phenomena.
|
|
|
|
' R sky was clear, while above the clouds were so dense as to mie various possib e ty es of hypotheses which may
|
|
obscure all evidences of the parhelic circle [ ? 1. The par- be made to account for t e maintenance of the earth's
|
|
|
|
helia were about 23' distant from the sun.
|
|
|
|
charge are capable of being grouped under thrse heads:
|
|
|
|
At about 6 p. ni. on July 2, 1914, a coniples halo with (1) We may imagine that negative electricity is fed into
|
|
|
|
three parhelia was observed. The two brightest parhelia the earth from the outside in some unspecified manner.
|
|
|
|
were vertically above and below the sun, while the par- In this case i t will bo necessary to assume that the vertical
|
|
|
|
helion to the south or left of the sun was but little more conduction current is dissipated again into SpaFe.
|
|
|
|
than an irregular splotch of light. The phenomenon (2) We may imauine that negative electricity is s u p p h d
|
|
|
|
lasted about 45 minutes, and O C C U I T ~ during a general c.ontinuous1y to &e earth and positive electric.ity to the
|
|
|
|
rain over western Tesas; for this reason it is supposed atmosphere a t dl places. (3) We may imagine that
|
|
|
|
that this station was in the outskirts of the alto-stratus negative electricity is supplied continuously to the earth
|
|
|
|
cloud region. No color was observed in the phenomenon, and positivo e1ec.tric.ity to the atmos here, the supp
|
|
|
|
and no rain followed at Fort Worth within several days. taking place, however, over only a !limited region a t
|
|
|
|
Many of the 22O-halos occur with a cirro-stratus over- any one time.
|
|
|
|
flow which precedes the inconiing high. These halos are Considering the hypotheses of the first type, it turns out
|
|
|
|
almost invariably followed by northerly winds and rarely that in view of the fact that the earth is a comparatively
|
|
|
|
by precipitation. Local thunderstorms are frequently good conductor of electricity, the charge will distribute
|
|
|
|
preceded by halos, usually 'solar and occurring during the h e l f uniformly over the earth's surface. The known fact
|
|
|
|
morning hours. These halos are followed by the usual that the conductivity continually increases with altitude
|
|
|
|
meteorological conditions preceding a thundershower. to a high value is all that is necessary to insure that thin
|
|
f It is also observed that halos occurrm with brisk south will arrange themselves so that the positive cha e in t e
|
|
P T winds and falling pressure will not be ollowed by rain if atmosphere is equal to the negative c.harge on t e earth.
|
|
|
|
the wind shows n tendency t o inc,rease in velocity and Considering the hypothesis of type 3, it turns out that
|
|
|
|
shift to the southwest!,hut that hnlos followed bv soutsh- in regions whero the replenislimont of charge to the earth
|
|
|
|
P west winds rind risiiio pressure will nlmost invariably be and titmosphere is not taking place, the otential-
|
|
|
|
followed by ruin w i t h 24 hours.
|
|
|
|
gradient =id earth-air current-clensjty wou d, under
|
|
|
|
Halos are not infullihle weather signs, but when prop- ordinary conditions, c~uiclilyf d to a11insignificrtnt d u e .
|
|
|
|
erly considered in conjunction with other fcntures they If, liowever, a very high vaho is assumed for the conduc-
|
|
|
|
serve as a material aid to the forecaster.
|
|
|
|
tivity of the upper atmosphere, this difficulty to some
|
|
|
|
d extent vanishes, and the assum tion of a rephnishment
|
|
of the charge at one place is su cient to account for the
|
|
|
|
maintenance of atmospheric-electric phenomena at all
|
|
|
|
OBIGm AND MAINTENANCEOF THE EARTH'S ELECTRIC CEKRGE.'
|
|
|
|
places. A discussion of several former theories is given; among
|
|
|
|
By W.F. G . SWANN.
|
|
|
|
others, those of Elstor and Geitel and of Ebert. In theso
|
|
|
|
(Read at the special meRting on atmospheric physics of Section I3 9merican Association lor the Advancement 01 Science, San Francisco, Aug. 5, ii115.) [Author's abstract.]
|
|
|
|
thoories a separation of positive and negative. electricit
|
|
d takes place in such a way that.ne ative electricity is 1 t
|
|
H on'the earth and positive is supp led to the atmosphere.
|
|
The positive charge is carried upward by the ascending
|
|
|
|
The aper consists of two parts. Part I is devoted to a air currents, and in the steady state; the convection cur-
|
|
Y enera discussion of certain broad princi les which n u s t rent so produced must be equal and opposite to the con-
|
|
% %e considered in the formation of any t eory of atmos- duction current. Apart from the objections which have
|
|
|
|
a. heric-electric phenomena, and to a consideration of
|
|
Former theories. I n Part I1 a new hypothesis is 110visionally forniulated, and its consequences are trace
|
|
Part I commences by considering the possibility of a
|
|
9 general circulation in the atmosphere b which the n g n -
|
|
tive electricity flowing upward at one p ace is conducted
|
|
|
|
been raised by others against the Elster and Geitel theorg, it is shown that, owing to t,he conductivity of the atmosphere, the rising positive electricity would become de-
|
|
fl voured, as it were, before it had reached any reat alti-
|
|
t,udes, and the net result is that on such a t eory the otential-gradient and earth-air current-density would
|
|
|
|
B down at.sonie other place. It appears that such an es- { e ex octed to diminish to practicdy a zero value at altitu es of the order of maggtude of 1,000meters, whic.h
|
|
|
|
1 Reprinted from C'arnegle Institution of Washington. Ywbook No 14 lor the venr
|
|
1915 pp. 339441. (Tautof the paper appears in full In Terrmtrlsl G e t i s m , " 6ep ternher, 13l5,40:105-126.)
|
|
|
|
is contrary to the results of balloon experimenh. The objection here cited applies to any form of theory in
|
|
|
|
Unauthenticated | Downloaded 01/09/24 04:26 AM UTC
|
|
|
|
~ ~ A E19Y16.,
|
|
|
|
MONTHLY WEATHER REVIEW.
|
|
|
|
69
|
|
|
|
which the convection current is supposed to balance the In the simplest case, where talierate of emission of cor-
|
|
|
|
rxnduction current.
|
|
|
|
pusclos and the nvcmpc? rango of a corpuscle are inde-
|
|
|
|
The hypothesis provisionnlly foriiiulnt~odin Part, I1 pc?iir1oiitjof tlic a1t.itudc, the! corpuscular current-density
|
|
|
|
consists in assuming tlint (?:1c11 cuhir c.entinitit)c!rof bhc :uid c.i)iiwquniitlythc c.onrluct,ioncwrrmt-density should
|
|
|
|
atmosphere emits negative corpuscles of :I poii(!t.r;it.ii)g ( ~ O ~ T H I L Y t~,?o Imwtirdly R mrc, vttlue nt an altitude com-
|
|
|
|
power sufficientlygreat to eiidde t.lioiii to tmvtd t>l-irough piirddt! with thc average range of a corpuscle. In the
|
|
|
|
considerable thicknesses of the zitniospliere. The t?art.li iiioro gtxierd ciise whore the rate of corpuscular emission
|
|
|
|
d l absorb tho corpusc.lt?swhich f d . upem it., t ~ a dit,s and t'licr rango of the corpuscles increaseswith the altitude,
|
|
|
|
potential will rise, in a negative S ( ~ R C ,until t,lia negat.ire thc ritriat,ion of t.hc co~iiluct~iociui rrent-density with dti-
|
|
|
|
conduction-current,hack to the various patrts of t,lic?ntmos- t4udehecomes iiiore coniplos, mil it beconies possible in
|
|
|
|
phere balances the char@ offect due to t.he ospulsion a nst,urnl wny to explain on these linns t8hegeneral fea-
|
|
|
|
of the cor usclos. The t o t d positivo ctharge in tlie :itmos- tures of tho variations of tlie conduc.tion current with
|
|
|
|
phere wilfof necessity hc: cqud to the iiegat.ivochargo 011 alt,itude in so frtr ns this variation is known. The argu-
|
|
|
|
the surface of the earth. In the stcndy s t d o t,hercsultnnt iiiont in this connect.ion is too involved to be made clear
|
|
|
|
downward corpusdar c,urrent.at, nny dt.it.ucle will just in an nbstract, and a, similar roinark ap lies to a c.onsid-
|
|
|
|
balance the upward coiiductioii curront at, tliat nltit,uclo. erat>ionof the cluesttionof nniiual and $urnal variation ;
|
|
|
|
A general considerabion of t,hc ordor of n i q y itwle of the it nuiy be remarked, however, that the more prominent
|
|
|
|
phenomena conceiiied shows that it is only necessary to foatures of these variwtions fall into natural line with the
|
|
|
|
8saunie an estremely snitdl rats of eiiiissioii uf corlmscles conclusions resulting from the developnient of the
|
|
|
|
t per cubic centimeter, and though the degroo of mietm- hy othesis.
|
|
tion necessar for these corpuscles is grt?atcr t imi ainv xi conclusion, it is to be remarked that there is con-
|
|
|
|
we are famil?ar with in laboratory esperiniaits, R fuh siderable latitude in the esact nature of the hypothesis
|
|
|
|
consideration of all the circunistnnces shows that the which niny be formulated in order to account for the
|
|
|
|
assumption is not as unreasonnble as might)ab first sight general features of atmosi>heric-electricphenomena dong
|
|
|
|
be supposed.
|
|
|
|
the above lines.
|
|
|
|
Unauthenticated | Downloaded 01/09/24 04:26 AM UTC
|
|
|