Helena weekly herald. [volume] (Helena, Mont.) 1867-1900, 1880-06-03
STORMS IN HE UNITED sTaTEs
They Travel Over Eighteen Hundred
Miles in Twenty.IOur Hours.

Professor Loomis has recently published
solne results OF an elaborate critical study an(
comparison of signal service observations anC
weather maps carried on for long periods, t
oiscover the movements and progressive We
loclties OF United States storms. Some o1
| his deductions are of great interest. He finds
| mat United States storm centers after cross
| Ing the Rocky Mountains move towards the
southwest until reaching the Mississippi basin,
when they incline toward the lake region
with accelerated speed. The average velocity
OF American storms after crossing the Mis-
slsslppi, about twenty five miles per hour, is
sixty per cent. greater than that of European
storms. This appears paradoxical when we
remember that in Europe the westerly winds,
unobstructed by any coast range like the
Rocky Mountains running north and south,
attain more rapid movement over the CONT
nent than the same winds can acquire in the
United States. But it appears from Professor
Loomis's examination that our storms when
nearing the lakes, and subsequently, are SUBJ
Jected to a powerful propulsion from the
waves OF high pressure which close in behind
them while in transit, and the rapid torren-
tial precipitation of rain in their front qua
drants by which the air is greatly rarefied
and barometric channel cleared for the free
onward movement.
In Europe it is very rarely that storm ad-
varces over thousand miles in day. But
in this country such an occurrence is much
more frequent. The storm centre of January
Z, 1877, travelled 1872 miles in twenty-four
hours, and that of the following week (Janu-
ary 14th-17th) travelled l ,270 miles in twenty
four hours. The storms which have been
found to make their way at this terrific speed
across the United States occur on an average
about once in forty days.
But one of the most remarkable features of
these great hurricanes is their shallowness.
The tremendous cyclone of the last-named
date passed Mount Washington without dis
turbing its summit, where the signal-service
observers vane recorded steady wind from
one quarter during the progress of the de-
preston at its base. During one of the
fiercest ''cold waves of high barometric
pressure, the thermometer on the summit
$1,000 feet high) showed higher temperature
than that prevailing at the base, clearly indi-
eating that the Arctic wave was not deep
enough to cover the mountain. These and
similar illustrations of the vertical proper
lions of both polar waves and barometric de-
pressions 90 to prove that the chief agitation
Of the Prial ocean Is limited to its bottom
strata, leaving the loftier regions of the at
nosphere in undisturbed repose, save when the
great upper current from the equatorial belt !
8 in the ascendancy.
AS many of the great storms which sweep |
)ver the United States are under the control !
If barometric pressures lying outside of our |
national territory, Professor Loomis points |
out the necessity of extending the signal |
service observations to extra-territorial sta
ions, not only with view to their complete |
,lucidation, but also for the practical pur-
poses of weather telegrophy.