Evening star. [volume] (Washington, D.C.) 1854-1972, 1896-04-18

ASVSA8Se-~O StrumentS 10 lueSe
s-- vaporous masses. to
learn their exact
r.TX&-.. heights, dimensions,
z&8HEHs@@ directions. vclocities,
t..13ss%KSa~ capacities etc.
e: .:E'Hss Elaborate prepara-
tons are being made at the national weather
bureau for this novel line of special study,
purposed to greatly increase the weather
wisdom OF Its forecastcrs and observers
Very little is now known concerning the
actual measurements, motions and positions
of clouds, although the latter the most
conspicuous factors of daily weather pre-
dicton.
The Survey stations.
The new cloud surveying will begin on the
list of next month, to continue exactly one
year, in conjunction with all of the other
weather services of the world. The prlnct-
pal observations in this country will be
made at Washington, but other selected
stations in various states will cooperate.
The United States, having the greatest con-
tinuouS extent of territory and the most
efficient weather service of all countries
Interested, will establish the most stations.
The principal cloud Observator.es are being
new arranged at New York, Blue Hill OBJ
serVatory, Boston. Buffalo and Detroit. The
latter two cities will study the cloud forma-
lions over the lake regions Representatives
of the different national weather services
have been arranging for this extensive work
for several years. A uniform system of
observation was lately agreed upon by the
International meteorological congress, held
at Munich, and, according to this. all studies
IN the various countries will be made stimuli
taneousy.
Chief Moore has appointed Prof. Frank
II. Bigelow. one of the weather bureaus
Grief meteoroloSsts, to direct the work on
behalf of the United States.
The Object.
The result of the cloud survey will be
the beginning of a great map of the at
mosphere above, the earth. When geolo-
gists plot chart of the earths crust they
show each layer of mineral strata These
meteorologists will show IN their new map
the layers of gaseous strata above the
earth. Such a chart. If made in model
form, would fit over 4 globe like the thin
hull of walnut.
The skilled eye of the met aorologist has
learned to tell which clouds are higher than
others. By measuring the precise distance
between d cloud apd the earth and by
learning its exact direction, they will know
that there is a current Of air at the same
height, moving in the same direction
When they learn the velocity of the cloud
they will know how fast the air cur
rent Is moving. '-f
But how will these measurements be
made? The surveyor may measure the
height of mountaiu by using the theodo-
lite He first establishes q base line on the
angles to be used in his comtrtat ton. By
applying certain formula he estimates the
dimensions of the mountain by triangula-
ton. A cloud might be called a great
mountain or mountain-chairi of vapor
Measuring Heights of Clouds.
Prof. Bigelow has established his base
line between the top of the weather bureau
and the west pavilion of the State, War
and Navy Department. Both stations are
each Observatory VIII be placed a theodo-
lite. especially fitted for cloud surveying
suppose That conspicuous cloud appears
in the north. The observer on the wea Their
bureau tower calls the observer at the
other end of The line by telephone and they
agree upon certain point at the top of
TIE cloud. They compare watches and
agree to take measurements al the same
minute precisely. The angles are jotted
down in their noe books. \ similar meas
urement is made straightway at a point at
the bottom of the cloud and at either end
Similar measurements may be repeated ev-
cry minute or two. as long as the cloud
remains in sight. By comparing notes and
applying formulate they afterward learn
how high the cloud was above the earth
how high it was from bottom to ton how
long from end to end, now far it Travelled
In given time and what was it's direc-
ton. Such measurements will continue
during each working hour every day, dur
ing the year specified. AS soon as one
cloud is finished another will be taken IN
From May 1. 1896, to May l. 1897, all sorts
OF clouds will be seen, representing every
phase of usual weather.
Cloud Classification.
That cloud observations of one country
may be understood by all others an inter-
national cloud classification has been late
ly agreed upon. Clouds have been divided
into classes and named according to their
characteristic forms. From many photo
graphs taken at various times in different
parts of the world one view of each rep
resentative form has been selected Half
tones of these, each labeled with its proper
name, are being made and will be distrib-
uted among all branch stations of the
weather bureau and such persons as NAV
care to aid in the study. Every observer.
whether connected with the international
survey or not, will be Instructed to asso-
ciate the proper names with the proper
clouds and to call them accordingly in all
dispatches, warnings. etc. The new clas-
sifcation will therefore be of interest to
the general public who will hereafter hear
considerable about various clouds.
The whole cloud system, Prof Bigelow
says, rises in the morning, until noon and
then continues to fall. The hotter the day
delicate Cirrus feathery clouds. the
highest class are mile and a half higher
in summer than in winter. All other
clouds vary in this respect in similar pro-
third of a mile higher in hot than in cold
weather. The upper clouds are found to
move always from three to four TIM s fas-
ter than the lower ones. In extreme casas
they travel one hundred miles an hour In
tornadoes, on the contrary, the wind near
the ground is. of greater velocity than that
mile high.
The Results.
The practical Talue of this coming year
of cloud surveying Nill be apparent soon
after the close of TIE measurements Oh
servers of the weather bureau will be able
to telegraph to headquarters more definite
warnings of the Appearance of danger
clouds over the horizon, just as scouting
vessels will be. abls to notify the Navy
Depar tment of the fsEst appearance Of hos
tile vessels near our seatoasts in case of
rections and other "details Of threatening
clouds thus appearing to any of the border
observatories, the authorities here at head