The Barre daily times. (Barre, Vt.) 1897-1959, 1903-06-20
ORlGlNOF CLOUDBURST
Scientific View CT Type Which
Wrecked HeppncT, ore.
HILLS AND M0UETAIE8 A MENACE

How an onrushing cyclone EnfoId-
ing a thunderstorm as II Strikes
Them Is Capable OF Producing a
Genuine cIoudDurst-TerriGe Force
OF che water as II Is Let Loose.
Cloudbursts Of the gigantic type
which caused the cataelysm at Hepp-
ner, Ore, the other evening are almost
invariably the result Of m interference
Of hills or mountains with the onrush-
ing whirlwind Unfolding an electric
storm, says the New York Herald
To obtain a clear idea Of this terrible
phenomenon one must first remember
that the thunderstorm Is strong hori-
zontal gyration Of the air-in fact, a
small cyclone, which has progressive
as wen as a rotatory motion. AS the air
begins its whirllng motion the cen.
trifugal force Of the outer ring causes
rarefaction in the central area Of tie
whirl. Inrushes of air from all sides
Of the storm then take place, especially
at its base, aud these masses of air
quickly form powerful and rapid
ascending current In the heart Of the
nascent tornado.
The genesis of the whirlwind is now
complete, but its gyratory motion is
usually soon intensified by the existing
hygrometric conditions.
If the atmosphere of any region.
whether 1t be level or mountainous,
contains a large amount Of water VA
por, the ascending current in the center
Of the thunderstorm viii have its vol
ume and velocity largely augmented.
This is easily understood since the
moist uprising air in the center Is con-
stantly reaching cooler and cooler
strata of the atmosphere, where its
yapor is condensed into rain or hail.
Moreover, the condensation Of the va
por contained fiji the ascending current
is further and intensely chilled by ex-
pansiou as it enters higher and higher
levels. where the barometric pressure
is greatly reduced until, at 1000 or
.. 600 feet above the earth, the rising
column of air, capped with magnificent
cumulus clouds, has much Of its mois-
ture wruug out Of It in the shape of
heavy raindrops. often intermingled
with hail
In this second and Incomplete stage
Of the storms development the rainfall
Is frequently excessive beyond the
power be human comprehension, The
precipitation in q short time amounts
to hundreds Of thousands Of tons of
water to the square mile.
During the passage of series Of
I thunderstorms over Syracuse, n. Y,
on June s, 1876. eight inches Of rain
4 fell. and it would not be difficult TO
cite many Ike records Of torrential
4 downpours occurring in a comparative
4 III level country When it is borne in
mind that a single inch of rainfall over
( one square mile weighs. in round num-
4 bers, 60,000 tons, it can readily be In
4 ferred that 4 fan half Of that regis
4 tered at Syracuse within a day, If de-
scending upon plain or valley carved
/ by several converging streams, Is fully
\ competent to create gigantic flood,
and where the ground in which the
converging streams meet is slightly de
pressed the food can become a rush
/ ing. irresistible wall Of water.
But when, DIS on Sunday. June IA,
| the storm in Oregon advanced upon the
mountains, the drainage of whose
slopes converges near Heppner, the
case was very different from that just
cited as occurring in a level country
In advancing upon hills.o or mountains
of moderate elevation the tornado
whirl, or even a severe thunderstorm,
is capable Of producing the genuine
cloudburst. In the immediate center
Of the storm. on its approach TO a
mountain, where we might expect the
heaviest rain. the raindrops, falling
from cumuns cloud, are arrested
and massed up aloft By the action Of
I the powerful ascending current, and
this process of massing the rain in the
folds of the storm cloud goes on as
long as the cyclonic or rotatory motion
Of the storm is fully maintained.
Standing Immediately under the
center Of the whirlwind one might
then notice but little and possibly no
rain. because there the uprising cur
rent prevents the downward rush Of
the water. Bur when the cyclone in
its swift flight strikes a range Of nils
or mountains the rotatory motion Of
the storm is mechanically stopped, its
Igyration ceases, the ascending current
in its central area can no longer sup
ipoft the masses Of rain collected In
tho high storm clouds and as the body
Of the travelling whirl scales the noun
tain top the accumulation Of rain in
tine upper region falls with terrific
force upon the leeward side Of the
mountain. sometimes exeavating holes
| six feet deep and thirty feet in diam
letter.
| The result is precisely the same as
lif d lake could be suspended in mid
lair for time and then allowed TO
drop en- masse upon the soil. As far
ms the geography Of the country
4.,4ttt9 TTopt.4{ats gan no determined. IL