The Saint Paul globe. (St. Paul, Minn.) 1896-1905, 1899-04-16

gions. they must go to the tropics in order
to sail west. So much for the motion Of
the clouds.
Prof. Bigelow's computations4give us
1 our first knowledge of the relative We
locity at which our differenf forhas of
clouds travel, the mean heighta a. our
various cloud strata, and the Average
depths of the latter. The most sensa-
| tional interest doubtless attaches to his
| measurements of thunder-heads or
''cumulo-nimbus' forms-the giants of the
whole cloud category. Some of these
measured In July were seven and one
| half miles high, from base to summit.
| and touching a height in the heavens all
most ten miles above the earth. Such
snow-capped mountains Of vapor: are
higher than any actual mountains on
earth. Deodhunga, now believed to be
the highest peak of the Hima1ayas, and
therefore the highest on earth,r measures
but five and one-half miles from base to
summit or two miles less than some of
these large thunder-heads. In passing
their bases seem seldom to hover nearer
than a mile above our heads They do
not appear In the sky from November
to the first of March. Before disappear
Ing entirely in November they form to a
height of only a quarter of a mile from
base to summit.
SIX MILES UP.
The very highest of all cloud forms
mentioned as travelling at rate of from
seventy-five to ninety miles an hour, are
those isolated, white, feathery forms Of
fine, fibrous texture, apparently motion
less, which we see on very clear days
converging in long chains toward some,
point on the horizon. Their mean
height was a trifle over six miles above
our heads, though they we're sometimes
located as high as ten. They were low
EST in mid Wh
fall within three and one-half miles of /
the earth, and continued thereafter to
rise until September. Within the same
atmospheric zone were located the scir-
ro-stratus' cloud, those white, Xefl-like
forms which frequently cover portions of
the sky or give halo to the sum- Fhe
upper and lower limits of their zone We're
located at three and three quarters miles
inside those of the CIRRUS" The famil-
lar white, shadowless, f1eecy clouds
"cirro-cumulus,' were located next be-
low at mean height of Ave miles,
and were found to dart through the air
at a normal speed varying from u to IS
miles an hour. The "alto-stratns, those
bluish-gray wells which often produce
cOrOnae around the sun or moon; are
found to travel at a normal rate varying
from sc to rs miles an hour at mean
height of S1a miles The familiar chains
Of grayish, f1eecy "alto-cumufus' clouds
WClC 4OuAO " travel III I'LL average sSpcSO
from so to 66 miles an hour and generally
at height trif1e less than three miles.
The same velocities were attained by the
dark, ball-like, rolled forms Of "strato-
cumulus" which, at mean height of a
mile and half, give the sky an undul-
ated appearance. The wool-pack clouds
known as "cumulus," those with dome
like SUBMITS but fiat bases. were found to
average % miles hour in low and 26
miles an hour in high pressure regions.
Their mean height above the earth was
calculated at a trifle over a mile, Still
below, Prof. Bigelow located the ,sstra-
tus" or lifted fog which when measured
was found to be a thin HORIZONTAL stra-
trm, commonly within a half mile sof us
and at a normal speed of % miles an hour.
Unlike other clouds, this appears to ven
ture higher In the skies in cold than 1t
does in hot weather. After beginning to
grow thinner in September and October,
the belts or zones of all clouds above the
wool-pack forms, appear to thicken again,
though slightly, In November, or about
the season Of the Indian summer.
WHEN OFTENEsT SEEN.
Interesting data as to the frequency Of
the different cloud forms have teen col
lected according to months. The feath-
cry cirrus were found to appear in great
eat abundance in March; the hazy GIRO
stratus in December; the f1eecy GIRO
cumulus In July; the graytsh-blue, thick,
veil-like alto-strar9s, in September. the
dark chains of alto-cufnulus in August
the frowning, wave-lke stratS-cunluusA
In the belt of greatest storm velocity-in
the present month, April; the wool-pack
or cunulus In August. the lifted fog or
stratus in June, and the thunder-head or
giant cumulus-nimbus, as might be ex-
pected, in July.
Prof. Bigelow is now at work upon
interesting statistics which will actually
show the pressure, temperature and va
por of certain cloud forms. In making
these computations he employs method
devised by him especially for the present
cloud work and never utilized before. The
resulting data shows that it Is no exag-
geration to mention the giant thunder
| heads measured rs "snow-capped noun
| tains Of vapor,' as was done above. The
| temperature upon the summit of one Of
| these seven miles high from base up
! ward, observed and measured ON July 30
| midsummer-was found to be Is degrees
| below zero, C. Thus the temperature Of
| the air at the too Of thunder clouds Of
such dimensions may, in midsummer, be
| as cold as the ground temperature in the
polar regions in midwinter If upon
| summer day we should rise in balloon
| and penetrate directly through one Of
| these giant thunder clouds entering the
! base and making our exit through the
| summit, Prof. Bigelow says we would
| traverse first a region of dry air and
| vapor then region Of dry air, vapor
and water, next region Of freezing va
por, water and ice, and finally one Of dry
air, vapor and Ice, but no water,