Chicago eagle. [volume] (Chicago, Ill.) 1889-19??, 1903-07-25
WHAT AcLouo BURST REALLY 10
Result 10 ~ II the Bottom Dropped
Out Of Suspended Lake.

When We read In the newspapers
that "tloudburst' has occurred some.
where and has resulted In great loss Of
life and destruction Of property we are
prone to consider the term merely one
used for a sudden and excessive rain
storm. While. Of course, 1t would be
wrong to consider a cloud as grea.
bag or envelope filled with water. and
which has only to burst In order to de-
luge the earth beneath. there IL really
such a thing as "clOudburst" as dis
tinguished from Il rainfall. however
heavy the latter may be. The New
York Herald gives clear ana interest
Ing explanation Of just what Il "cloud.
burst" really Is and a study Of the
phenomenon will prove OF interest. par
dcularly as 1t was u genuine "clOud-
burst" which II few days ago practical
ly wiped the town OF Heppner, Oregon.
from the face Of the earth and de-
StrOyed some 200 lives.
The "clOudburst" Is always preceded
and caused by a windstOrm or small
cyclone, the air whirllng In circle and
at the same time moving along hori-
zontally. As the air whirls about In a
circle 1t forms sort OF cone with the
apex ut the top. This whirling motion
causes an thrush Of air from all sides
at the base and these masses of air
quickly form powerful and rapidly
ascending current In the heart Of the
nascent tornado.
Now, II the atmosphere through
which this windstorm Is passing IL de.
void OF moisture, there will be no rain
fall. but II there Is quantity OF moist
IRE In the air the ascending current In
the center Of the tornado will natural.
~, In carrying great quantities of It
skyward, pile up this moisture In the
form Of cloud at the top. This cloud.
being In colder stratum of air. speed.
lily becomes densely saturated with
moisture. Under ordinary circum.
stances this moisture upon being con-
densed into drops would be precipitat.
Cd to the earth, but In this instance the
pressure Of the upward current pre-.
vents 1t falling. On the outskirts Of
the cloud, where the pressure IL less,
rain does fall, but at the apex Of the
whirlwind 1t continues to become more
and more dense.
Finally the conditions become 90 that
the column Of ascending air 10 sup
porting above 1t veritable lake. Now,
20 long as this air pressure 10 main
tained the water cannot fall. but az
soon as the storm strikes q mountain
the raised land breaks and destroys the
whirlwind aud the water 10 permitted
to fall-always on the leeward side Of
the mountain. The water comes down
in Q perfect deluge. much the same 90
II lake had been suspended In the
heavens and the bottom had suddenly
fallen out. II the "cioudburst." a. this
10 called, takes place over q narrow
valley down which the great mass Of
the water must dow to And h level one
can readily see what force It must
bring to bear on everything which
stands In the way. When It 10 borne In
mind that single inch OF rainfall over
one square mile weighs 10000 tons. 1t
10 not difficult to imagine what q rush
Of water follows the sudden downfall
Of several inches over Q space Of even
much lees than . square mile.
4 glimpse OF TIE illustration furnish.
"a On thas page viii make very plain
~ sosgatSea Of this terribly dsstrue.