MAY, 1908.
dim, Nicol or no Nicol, showing that the typical autumnal
haze, often whitish blue near the horizon, acts mainly by gen-
eral obstruction and diffusely reflecting a good deal of light,
the polarized component being usually only motlerately strong.
Haze in general is well known to be due simply to suspended
particles of one sort or another, and haze which produces
polarization, as well as the ordinary sky polarization, is well
known to be due to particles, whether of dust or water, or of
other nature, small compared with the wave-length of light.
Lord Rayleigh' has given the theory of this action in consid-
erable detail.
The polariscope integrates the effect of such particles along
the line of sight, and this information may have considerable
ineteorological significance. The light-scattering particles
which produce sky polarization are much finer than those
which produce coronas and similar phenomena, with the be-
ginnings of ordinary reflection. I n artificial fogs the nuclei
gradually grow from the polarizing dimensions to those which
scatter white light and become visible. It is not easy to
assign exact dimensions to the finer particles. They are quite
certainly much less than a quarter wave-length in diameter,
that is, say 100 pp, and probably run very much smaller.
From the very exhaustive work of Barus' it appears that the
diameter of the particles to which visible fog and coronas in
a fog chamber of laboratory dimensions are due range from
.0005 11 upwards, those near this limit showing as fog, while
the coronas began to form as the diameters reached 10 [A and
above. The fog particles to which lunar coronas are due often
rise to greater dimensions, 20 or 301~.
Now such fog particles are the preliminary to rain, which
forms by the accretion of these particles to 11 size that readily
falls; and it is well known that water vapor, even when satu-
rated as shown by the psychrometer,.will not begin to con-
dense to visible fog unless in the presence of nuclei about
which aggregation takes place. These may be of very fine
dust, or even of water particles electrically charged to an es-
tent that resists the surface tension that would otherwise pro-
mote evaporation. Such charged aqueous nuclei may exist in
unsaturated air at very small diaineters, down to 1 or 2 i q ~, as
has been shown by J. J. Thomaon,' by Wilson: and by others.
Between these almost molecular dimensions and those indi-
cated by coronas are the light scattering particles active in
sky polarization. Their effect, that is, the amount of light
scattered, varies, as Rayleigh6 has shown, as the inverse fourth
power of the wave-length of the light affected and directly as
their volume, assumed to be small compared with a wave-
length. Now plotting the resulting equation, I = -, one ob-
tains a group of curves shown in fig. 1 [omitted], which die-
closes the cause of the familiar intense blue of the scattered
light. As larger particles grow during the process of nuclea-
tion or are present as dust, the blue gets weak and whitish
from the scattering of white light. Near the horizon, where
the light traverses a long reach of atmosphere and coarser
dust is common, one gets the familiar weakening of the sky
blue.
The process of increasing nucleation, which resid ts in cloud
formation and frequently in subsequent rain, can be followed
very closely by the polariacope. A fall in polarization, par-
ticularly when the spectroscope shows the presence of much
aqueous vapor, indicates the progress of nucleation.
On several occasions I noted this phenomenon in the Breezy
Point observations. Starting with strong polarization on the
distant hills to the southward and a strong rain band visible
in the spectroscope, the nest few hours showed a conspicuous
K A
#I4
145
'Phil. Mag., 1871, p. 107 et seq. aSmithsonian Coot.. No. 1373. *The Discharge of Electricity thru Gases. JPhil. Trans., 1897.
e Rayleigh, loc. cit.
weakening of the polarization, followed presently by the for-
mation of visible clouds, and in at least two cases by precipi-
tation. In sliort, if from change of temperatiire or other
cause cloud is due to form in any particular direction, the
nucleation which precedes visible fog formation is bound,
other things being equal, to cut down the polarization. The
prognostic value of this process depends largely upon the rate
at which it progresses. In two instances which I noted, the
decrease toward the south occupied most of an afternoon. Of
course a drifting in of coarser dust particles would produce
weakening of polarization, but the concurrence of weakening
with a heavy rain band intimates very strongly that nuclea-
tion is progressing.
A detailed study of the changes would require the use of a
sensitive polarimeter, by which variations from the theoretical
polarization could be accurately measured. Observations of
this kind, made where there is a wide sweep of horizon, should
frequently disclose incipient cloud formation and the causes
which produce it. The use of a spectro-polarimeter would be
very desirable, as showing by the change in the quality of the
scattered light the progress of events. The nature of the
minute nuclei, whether dust or water particles, is not definitely
known. After a heavy rainstorm the lower strata seemed to
have been cleared pretty effectively of polarizing nuclei, while
the upper sky remained much as before. On one occasion,
more than twenty yearwago, I was taking rain-band observa-
tions on Moosilauke and was favored with a day in which the
distant peaks, even up to 100 miles, stood out almost as black
as silhouettes, while the sky took on a deep hue almost startling
in its unfamiliarity. A polarimeter would certainly have given
extremely interesting results had it been at hand. It seems
quite possible that one might get a fairly clear idea of the
relative number and distribution of nuclei in the upper air by
such means.
I t would certainly be interesting also to find out whether
the apparently very strong absorption of ultra-violet rays by
the atmosphere is due to any genuine absorption or merely to a serious loss of light by lateral scattering, which Rayleigh
has shown may perhaps be due to the air molecules themselves.
I n the lower strata my observations pointed rather to dust
than to minute water nuclei, since a whitish haze showed
powerful polarization on near-by peaks, making it clear that
the haze was extremely heterogeneous. The conditions which
would produce stable water nuclei of strongly polarizing size
on a clear day would tend to reduce larger droplets to the
similar order of magnitude instead of leaving them to super-
impose specular reflection.
I am not disposed to suggest that in the polariscope we
have a meteorological tool of vast importance, but my pre-
liminary observations certainly show that it gives a most in-
structive view of the very early stages of atmospheric nuclea-
tion, and especially if combined with rain-band observations
i t should have material prognostic value as regards comparr-
tively local conditions. There is also a chance for forming a
clearer idea of the conditions of nucleation in the upper air,
including the very high altitudes, since polarization is mani-
fest aftsr the sun is so far below the horizon as to illumine
only the upper strata. I bring the preliminary facts to notice
here in the hope that some one with a suitable location and
opportunity for systeniatic observation may find them useful
as a guide to further work along this line.
NOTES FROM THE WEATHER BUREAU LIBRARY.
By C FITZEUGH TALHAN, Librarian.
UPPER AIR RESEARCH IN GBEAT BRITAIN.
The active part that British observers are now taking in the
world-wide campaign of upper air research was reflected in the
prominence given to this topic at the last Royal Society con-
versazione held at Burlington House, May 13,1908. The sub-
ject was illustrated by exhibits by Dr. W. N. Shaw, J. E.
Petavel, W. A. Harwood, C. J. P. Cave, Capt. C. H. Ley, E. S.
Bruce, and the director of the Egyptian Survey Department.
Daily ascents are now made at the Howard Estate Meteor-
ological Station of the University of Manchester, situated at
Glossop Moor, Derbyshire, and the results are published in a
monthly bulletin. The work at this station is to continue for
two years from January 1, 1908. The necessary funds were
mainly contributed by Dr. Arthur Schuster, of the University
of Manchester, and Mr. J. E. Petavel ham immediate charge of
the observations.
Upper air observations are made by M i . Dines, for the Me-
teorological Office, at Pyrton Hill, Oxfordshire, by Mr. Cave at
Ditcham Park, Petersfield, and by Mr. 5. H. K. Salmon at
Brighton. I n connection with the scheme of simultaneous
observations under the direction of the International Com-
mittee on Scientific Aeronautics observations have been made
during the past year at several other points in the British
Isles.
A METEOROLOQICAL STATION ON THE ELBRUZ.
Globus of May 7,190~3, announces that a project is oh foot
to erect a meteorological and astronomical station on Mount
Elbruz (18,526 feet), the highest summit in the Caucasus.
The estimated cost, 20,000 rubles, the president of the Cau-
casus Alpine Club, M. Leutzinger, hopes to raise in part from
various learned societies.
This giant mountain, which forms a conspicuous feature of
the landscape of southeastern Russia, is much higher than
Mont Blanc, and, we believe, than any other mountain that is
at present the site of a meteorological station.
ENQLIBH ABSTRACTS OF JAPANESE METEOBOLOQICAL PAPEBEI.
The monthly Journal of the Meteorological Society of Japan,
now in its twenty-seventh year, has begun publishing English
abstracts of the Japanese contents of each number. This
excellent innovation makes available to occidental readers a
wide range of meteorological literature, as may be judged
from the following titles of abstracts published in the number
for March, 1908:
M. Ishida-Diurnal variation of the wind velocity.
I(. Asakura-Relation of the climate and tobacco cultivation.
M. Sato-Meteorological observations at sea.
J. Sato-On cloudy morning weather.
H. Ogiwara-The climate and rice crops.
Y. Takashima-Precipitation near Mokpo.
K. Bsakura-Remarkable rainfall at Yokohama on January
M. Ishida-Climate of south China.
The paper last named is a summary of observations made
for the last three years at Hangchow, Nanking, Hankow, and
Shashi, and is one of the first fruits of the recent invasion of
China by the Japanese meteorologists.
15, 1908.
METEOROLOQICAL EXPLORATION IN KAPCHATKA.
The Scottish Geographical Magazine states that a large
exploring expedition, organized by M. T. P. Riabouchinsky,
left St. Petersburg in May for Kamchatka Meteorology is
one of the principal subjects to be pursued by the expedition,
whioh will spend eighteen months in Hamchatka. Meteoro-
logical stations will be established at Tigil, Kintchevska vil-
lage on the Hamchatka River, and Petropavlovsk.
THE SYMONS PEDAL.
The Symons Memorial Gold Medal, which is awarded bien-
nially by the Royal Meteorological Society, has been presented
this year to M. LQon Teisserenc de Bort.
M. Teisserenc de Bort was a member of the staff of the
Bureau Central MQtQorologique de France from 1878 to 1892.
I n the latter year he resigned in order to devote his entire
attention to experimental research in meteorology, and in 1896
he founded a private observatory for the study of dynamic
meteorology at Trappes, near Paris. His recent work has been
chiefly in the field of upper air research, including the well-
known expeditions of the yacht Ot0ria (in connection with
Mr. A. Lawrence Rotch), and the comparison of upper air
temperatures in different latitudes.
EXHIBITION OF YETEOROLO(3ICAL AND GEOPHYSICAL IISTBUMENTB.
An international exhibition of meteorological and geo-
physical instruments will be held at Faenza, Italy, in connec-
tion with the celebration of the tercentenary of the birth of
Torricelli, during the months of August, September, and
October of this year. A prize of 2,000 francs will be awarded
to the meteorological or geophysical instrument exhibited
that is judged to be the best innovation, either from its
principle or from its application to some principle already
known.
WILLIAM M. RITSSON.
Mr. William M. Husson, whose death in his 53d year,
occurred in Washington, D. C., on May 10, 1908, entered the
Weather Bureau Service in August, 1890, and served contin-
uously as draftsman at the Central Office, with the exception
of about a year during the war with Spain when he was en-
gaged in the military service of the United States as Captain
of Company D, 1st Regiment, Florida Volunteers. He was a
skilful and intelligent workman and a man of excellent char-
acter and disposition.-H. E. W.
IUE MOVEMENTS AND CURRENTS IN BERING STRAIT.
Mr. James F. Cross, Government teacher at Wales, Alaska,
has for the past three years kept notes of the ice movements
and currents in Bering Strait. This spring, on May 28, in
response to a request from the special observer of the Weather
Bureau at Nome, Alaska, he telegraphed the following informa-
tion :
ApFiZB.--Ice all clear from the straits and was open water to the Dlomedes [Islands] and as far north and south as you could see. Current moving south. April 11.-Current changes and brought ice into the straits for Ave days. A p d 17.-Current south. Ice cleared and water full of young ice. Since this date no ice floes have come into the straits, and as far as you can see the water is open. The natives are not able [to] account for no ice coming down with both the wind and current from the north. Wind northeast, but the ice did not move up from the south. The current varies from day, to day. As the only way to measure is by the floating ice it is hard to estimate velocity. Compared with other years there is much less ice in quantity.
A letter dated February 23, at Icy Cape, says: The ice pack did not mme down from the north. Last reports from the Diomedes Islands indicate that the ice in the west straits has been light and there is now plenty of open water there. Walrus are running in large numbers east of Diornedes Islands.
April H.-Strong current from the south.
CORRIGENDA.
MONTHLY WEATHER REVIEW for March, 1908, Vol. XSXVI,
No. 3, Chart SIV, in lower left-hand corner the legends for
the two colors, green and red, should be interchanged,mali-
ing red indicate Not crost by paths and greea cccrost by
paths.
MONTHLY WEATHER REVIEW for April, 1908, Vol. XSXVI, No.
4 a e 87, column 1, second line of test of Chinook winds,
ekz,lFfor ccCharts IS and S read Charts XVI and S V I I .
Page 103, column 2, in Table 1, left-hand column, for cc Ghent 
read ccGeneva. Page 105, in Table 4, right-hand column,
line for July, for 0.495  read cc0.0495 .