The Dupuyer acantha. [volume] (Dupuyer, Mont.) 1894-1904, 1899-02-16
Chinook Winds.


the United States. Now whether
this assertion is made to bring the.
eye OF the people upon this partic-
ular spot OF this mundane sphere,
or sad IN praise of having some-
thing that can oe said of HaVre
that leads all others, ] know not:
but the statemen. is very mislead
ing in regard 20 the climatic
conditions that prevail in this
vicinity There are spells of cold
weather that with this nigh press
ure area, produce temperature of
about 409 below Zero onct in five
years in this loca ity out it is noi
given out that this cold spell lasts
only few days and is followed by
period Of the finest weather il
the world, caused by Chinook
winds that are so pronounced in
the northwestern part Ct Montana,
and the origin of which, the gem
eral public is so little Informed
Even the geography taught in the
schools of this state iu speaking OF
the climate of Montana says:
"But extremely cold weather does
not last long owing 10 the in
fuence of the win Is frou the great
Pacific Ocean stream, the japanese
current, which is analogous to thg
Gulf stream of the Atlantic, and
further "The warm winds known
as Chinook winds from the Pacific,
heated by the Japanese current
etc. /" Now the Japan current
theory in regard to thsse winds
has been completely eradicated and
disapproved and they are formed
under well defined meteorological
conditions aud are due to the me-
chanical or dynamic heating of the
air, changes of temperature 10 ver-
tical currents and the llb ration of
latent heat from condensiug yapor
must be considered in its explains
tion. The lower air. about to as
cend has a certain temperature
and a corresponding expansive
force when it begins to rise. AS
it reaches higher levels, the press
ure upon 1T is less it therefore ex~
pands, pushing away the surround
ing air to make room for itself until
Us result of its expansion, its ex.
pansive force is reduced to equality
with the pressure upon it. 1t
follows, however, from experiment, c,
as well as from the mechanical
theory OF heat, that in pushing
away the surrounding air, the as
cending air must expend some OF
energy; and this expenditure is
drawn from its store o! energy in
the form of heat, hence the ascend
ing air is cooled by the very
process inYolved in it's ascent.
The rate of cooling thus pro-
duced is accurately known; being
1.6 degrees on the f hrenneit
scale for every three hundred feet.
similar change, bat Of the reverse
order, occurs in the descending
member Of the correctional circula>
ton. AS the descending air
settles down, other air rolls on tor
of it; it is therby compressed to a
slightly greater density. and the
temperature is raised. When air
is thus changed in temperature,
1t is SAID 10 be mechanically
warmed or cooled The conditions
for our Chinooks is when low
yclolic center, moving eastward
over nothern Montana, and q high
pressure area eXtant over western
Wyoming and southern Idaho then
under such conditions, the cy>
ionic indraft causes the air from
the high pIateaus and tain
crrsts south and south west of
Havre to descend rapidly to the
10 Ntr bench aud and valleys from
height Of four to seven tnou sand
feet 10 twenty five hundred feet or
less, creating molecular action and
generating con siderable heat there
by and ; weeping into the Chinook
belt as warm. high south west
wiuds soon takin- the snow from
the around and changing the rlgor
OF winter to the mildnrss of spring.
The Fochns of Switzerland and
FONDA of the Argetiue republic are
winds belonging to this type.
Those who have not felt this warm,
inauguration Chinook winds of this