The Portland daily press., 1897-03-12
STUDYING THE CLOUDS.
Fresh Departure Engages Attention of
photographic Office.

cript.)
Washington, Feb. 26-The Hydro
graphic Office of the navy has taken up a
new idea. 1t is about to publish a
"cIoud atlas, ~ for the education of ordi-
nary folks in branch of science which
itself is wholly novel-namely, the study
of clouds and their poltents The atlas
will he offered for sale at the cost price
of sixty cents, including instructive text
and pictures of sixteen different kinds of
clouds; or one may buy chart of twelve
kinds of clouds for twenty cents. The
pictures will be executed beautifully in
ooIors, with incidental landscapes and sea
scenes. They have been prepared under
the critical eye of eminent psychologists,
or cloud experts, the artist bang MIR.
Rudolf Cronau of New York.
The most important purpose of the
cloud atlas in to teach mariners how to
observe and reporr accurately. More than
sixteen hundred ship captains and other
persons engaged in the seafaring business
act regularly as voluntary observers for
the photographic Office. They are sup
piled with blank forms. which they fill
in with notes as to storms and other
matters. In future the forms will pro-
vide for remarks on the clouds each day,
stating their kind, altitude, direction OF
movement, etc. The blanks thus filled
out are forwarded byssmail to Washington
by their aid the Government experts are
enabled to put tog ether tables of most
valuable data.
The data obtained in his fashion re-
speoting clouds will afford knowlege that
will enable the expert to predict storms
much more accurately than hitherto.
incidentally, the mariners Will learnkhow
to make better forecasts for themselves.
Since the beginning Of navigation sailors
have relied largely upon the appearance
Of clouds in judging of coming weather.
1t is obvious that they will be able to
Judge with much more Certainty when
they know how to differentiate the vari-
Gus species of clouds with scientific cor
roctness Credit for this new idea be-
longs to Commander Sigsbee. q. S. N.
now in charge of the photographic Office
who has already earned fame as the in
yentor of the devices now in use for
sounding the depths of the sea.
just for example, take the feathery
clouds sometimes called "mares' tails"
which float far aloft In the heavens.
They are in fact by far the lofti est Of all
clouds, occupying An ethereal region of
extreme cold five or six miles above the
earth. 1t 10 believed that they are COM
posed sometimes of needles Of ice; some
times of globulss Of ice, and sometimes
of globules Of water which is far below
the freezing point. Water may be kept
froo1ipr Of
Temperature Of 10 degrees above Zero be-
cause it has no nuclei for crystals of ice
to form around. In the very rare1ed air
of great heights similar conditions pro-
duoe the same effect. Balloonists passing
through such clouds have observed that
when the water giobuIes strike the bal
loon or any other solid object they freeze
instantly.
Now, the mares tails are supposed to
be overflow clouds from cyolonic storms.
They flow out from over the top OF suoh
great atmospheric whirls, and thus they
are the first evidence seen of an approach
ing cycionic movement Along the At
lantic seaboard of the United States they
are the forerunneIs of storms coming up
the coast. When they are observed. it is
time for mariners to look out. The
mares tails are known technically as
"cjrcus,' clouds. Belief as to their great
HEIGHT was verified by the balloonist
GIaisher who, when 81, 900 feat above the
soil of England Saw a fsathery network
far above him. The "cumuli, 4" or wool
pack clouds, as they are commonly
termed, usually float at an elevation OF
only about mile.
Clouds of all kinda are composed of lit
tie olobules of water. The globu1es are
yerv minute, though big enough to see
with the naked eye. Balloonists catch
ing them on their coats, have often eS-
amined them with magnifying glasses,
and the same thing may be done on high
mountain tops. 1t used to be supposed
that the globules were hollow, like soap
bubbles, because it was not easily I'M
derstood how otherwise they could be
held suspended in the air: but tn is
notion has been exploded. Every globule
has a particle of dust for nucleus. If
it were not for dust, there would be no
clouds and no rain, because the water in
the atm osphere would nave mourning TO
oondsDse upon.
Fortunately, it is not necessary to
climb a high mountain or go up In
balloon in order to study the makeup OF
clouds. A familiar phenomenon on the
esrth's surface is fog, which 1s true
cloud at low level. This kind Of cloud
is produced by the cooling of the air near
the surface OF the ground, the water con-
densing from the atmoshere around dust
particles The aqueous globules compos-
ing the fog or mist may be examined
under the microscope as they pass across
lis field. The familiar form of clouds
known as "s5ratus'' il merely horizon
tai sheet of lifted fog which floats at an
eleyatlonsof less than half mile ordi.
narily. The globules already described
grow bigger and bigger. in process of cop-
densation, hut they never become rain
drops. The real cause of rain is still
mystery. One theory is that 1t may be
due to the rushing together of atmos-
pberic vapor which can fnd no nuclei to
contlense upon.
There are more kinds of clouds than are
dreamed Of in most peoples philosophy;
but they are only notifications and
combinations of those already mentioned.
The "nimb bus" or rain-oloud proper, Is
a thick layer of dark cloud, shapeless
with ragged edges. The oumuio-nimbus
is the thuntier-cloud or shower-cloud.
Tbis sort Of cloud is formed IN heavy
masses. which assume weird shapes sug
aestire to the Eimaginative eye castles,
giants, extraordinary animals, etc. The
strato-oumulus lie thestypical storm cloud
almost always seen In advance of storm.
The alto-stratus is thick sheet Of gray
or blush cloud, with brilliant patch
near the sun or moon. The alto-oumulus
9 l,-Ca oil IN Of white