New-York tribune., 1900-12-02
UPPER AIR MOVEMENTS.
WHAT CAREFUL OBSERVATION OF THE
CLOUDS SHOWS
vELoCIrIEs. HEIGHTS AND DIRECTION OF At
MOSPHERIC CURRENTS ONER THE
UNITED STATES.

Meteorologists have long been convinced that
a systematic study of the clouds would afford
Information regarding the movements Of the
upper air which would possess great practical as
well as theoretical value. Balloons and kites
have rendered more or less service of this kind
But balloons costly and likely to be lost If
unaccompanied. and it is almost out of the ques-
ticn for man to ascend higher than five or six
miles, because of lack of air to breathe. And
thus far it has been impracticable to send kite
up more than two or three miles. Yet cirrus
clouds report the conditions at an elevation
OF from six TO ten miles Influenced by that
fact and other considerations the international
conference of meteorology in 1891 approved
scheme for cooperative observations of clouds
for 4 whole year in several Of the countries
Of the northern hemisphere. The plan was not
carried into execution until 1862, and the
report of the American observations, with
elaborate discussion by Professor Frank II.
BigelOw, has just been issued by the Weather
Bureau. The task was committed to good hands,
and has been admirably performed. Meteorolo-
gists cannot read the document without feeling
satisfaction over the results secured and the
broad, progressive way in which the facts are
handled.
A uniform classification OF clouds was agreed
upon by the International Conference Ten
types were adopted the basis Of observation.
The observers were carefully instructed how to
distinguish them, and months preliminary
practice undertaken before official records
were made. The work carried at fifteen
stations in the United States, all but one of
which were east Of the Rockies At each sta
tton an instrument called a nephesco2e was used.
This is round mirror, fixed IN i horizontal
position and having the degrees Of a circle and
points of the compass inscribed on It's edge
CIfifo nj nd he oh
server noted the direction Of the cloud move
ment, and with chronometer ascertaiueI the
apparent speed. The real velocity though. was
determined only after supplementary observa-
tions had been made with Il pair of surveying
instruments, to find the height of the cloud
under scrutiny. Observations were made several
times day when the weather permitted.
THE HEIGHTS OF CLOUDS
The results of this work having been tabulated@
and digested, it appears that in this country, |
east of the Rocky Mountains, the lowermost
type of cloud, the stratus, floats at an avera se
height of ., 700 feet in winter and $500 teet in |
summer Both in winter and summer the bases |
of cumulus clouds keep at mean elevation of |
3,@-x feet, but the domes sometimes reach a |
height of 5000 or 10000 feet The nimbus, or |
storm cloud, varies from $500 to 600 feet. The
average height of the cirrus in summer is $4,000 |
ally exceeded by three or four miles. In Sep
tember, 1896 cirrus clouds were seen at an eIe-
walton OF $4,000 feet, or over ten miles! Nearly
every class of clouds attains a loftier altitude
between the hours of and s p. IN. than at any
other part of the day, whereas between noon
and 4 o'clock they fall trihe below the aver
age
In velocity conspicuous variations are attrib-
utable to a change of season. Stratus for in
stance, floats along at mean of thirteen miles
an hour in warm weather, but accelerates it's
speed to twenty-four miles hour in cold
The tops of cumu travel thirty -four miles an
hour in summer and fOrty-seven miles an hour
in winter The average for cirrus in the former
season is sixty-seven miles and in the latter
seventy eight. But in March, 1897 the maxi
mum velocity observed was 1S7 miles while in |
the previous December cirrus was seen moving
al rate Of over two hundred miles an hourl |
Nice weather to get caught in with a flying ma
chine. Professor Bigelow remarks that from
this one years data it looks as if the greatest
speeds were realized at an elevation of seven
or seven and half miles, and that from that
level up to ten miles there was slight falling
on But further observation is required to
verify that inference before it can be accented
as final
fact that has been brought out moro clear1
by these cloud studies than ever before ie ,bot
The movement Of the air above the nimbus level
say six thousand feet, is practically independent
d the lower strata In the region covered hv