Evening star. [volume] (Washington, D.C.) 1854-1972, 1895-12-28
STORMS IN JANUARY
Turbulence in the Atmosphere is
Apt to Be Marked.
PROBABLE TRACKS OF TEE TEMPESTS
interesting Description Of How the
Disturbances Originate.
COLD WAVES CONSIDERED

Most of the weather conditions described
Ia December continue to operate in jan
uary, but with somewhat greater intensity
The turbulent changes in the atmospheric
circulation are more pronounced, and the
alterations Of fair and stormy weather
more decided. This is due to the. fact that
lower temperatures exist over the entire
arctic cap of the northern hemisphere,
while at the same time the atmosphere
within the tropics is maintained
nearly at summer heat, that
very rapid change in the Their
NAL gradient occurs in going south or
north along any meridian. Accompanying
this fall in temperature with the latitude,
the pressure also is relatively much alter
ed in the summer and the winter distrbu-
ton, such that in summer a large, nearly
permanent low area covers the arctic zone,
while in the winter this is divided into two
low areas by a comparatively high belt
crossing the arctic region. These lows are
central, one near Iceland. and the other
near the Alcutian Islands, while the high
belt passes over the British possessions
Fear the Mackenzie River valley. northern
Alaska, into northern Siberia, whence 1T
goes southwest to unite with the high pres
sure belt of the temperate zone. The ten
dency to accumulate masses of cold dry
cir in the British territory between the
Rocky mountains and the Great Slave lake
region Just east of them is of special sig
lificance in the study of the weather of
the United States in the winter. Since the
high pressure belt thus described lies
athwart the course of the current of east
ward drift that prevails in the upper strata.
1t is inferred that there is an effort going on
to break up the formation of any contin-
ucus area of high pressure in the arctic
zone. so that these masses of air are in
termittently broken off to drift eastward
In tie northern circuit, or southeastward
in the southern circuit. Ihasmuch as the
passage of a large high area is accompanied
by cyclonic circulation or low, on the front
and also on the rear sides, or in other
words. by areas of warmer air on either
side. it is seen that this condition tends to
produce rapid changes in the temperature
of the air that is thus moving eastward
over any district
Where the Air Begins to Circulate.
This northwest region is of especial inter-
est in the meteorology of the United States
for 1t is practically the heart of the circu-
lation of air that passes eastward, and If it
is possible to fully understand the action of
the forces operating there, it will become
much easier to generalize safely concerning
many other problems in the physics of the
atmosphere. 1t may, therefore, be proper
to present few statistics regarding the
northwest region. Unfortunately we pos
sess no suitable observations in the exact
region where the center of operations Is
located between the Great Slave lake and
the mountains, that are continuous over
series of years. 1t is found, however, that
the conditions thus generated drift forward
to the Dakotas in exactly one day, on the
average, SO that utilizing the observations
of the weather bureau in those states since
1873, we can form a definite idea of the
facts that are involved in the problem. The
record of the seventeen years, 1S1S-1S94
gives the following results for the contrast
between summer and winter. The mean
summer pressure Of the Dakotas is 1890
inches, and the temperature is sixty-seven
degrees: the mean winter pressure is 30. IA
inches, and the temperature is ten degrees;
winter includes December, January, Febru-
airy, and summer June, July, August. for
these conditions. The mean annual press
| ure is 30.03 inches, and the temperature Is
forty degrees. the change being twenty
four hundredths of an inch, and f1fty-seven
degrees Fahrenheit. These are the annual
mean values, and of course imply much
| wider ranges on individual dates.
Seasonal Changes Described.
Now, on examining the changes from day
TO day In the pressure and temperature, or
as they may be called, the amplitudes of
the warm and cold waves passing over the
Dakotas, 1t results that the barometer
swings up and down on the average of
thirty-five hundredths in winter and nine
teen hundredthS in summer, while the
temperature oscillates on the average about
20 degrees in winter and degrees in sum-
and lows passing over those states, and are
made UP of all the observed changes. large
and small, that occur in this connection,
some being wide and some very slight. 1t
would be nearly correct to double these
figures in order to obtain the wide indivi-
dual changes that can be noted. 1t is the
passage from the summer values to those
of the winter that make up the seasonal
changes, and when these are translated
into the winds, gales, hot and cold days,
as they come one after the other, it will
easily be inferred what a power these
small numbers really represent in the ac-
ton of the earth's atmosphere. In the
tropics, by way of contrast, the amplitude
changes are not one-fifth as large for the
year. The question naturally arises, what
is the exact action or energy in nature
forces to take place in the region to the
northwest of the Dakotas? This is pecu-
| liarly interesting from the fact that there
is no other region known in the northern
or southern hemlspheres where so great an
output of energy is observed.
Causes of Our Bad Weather.
The peculiarly rough type of weather
prevailing in the United States during the
winter, as compared with Europe or even
Siberia, is entirely dependent upon it.
There are doubtless a large number of
causes at work to bring about this re-
suit, yet 1t Is possible to specify some of
them, and this will be attempted in con-
| nection with the February storms, when
| this set of influences rises to the maximum
| power.
The stormy conditions thus generated in
| the extreme northwest are propagateG
| eastward in a series of irregular, spas
| modic discharges, storm drifts, that
| cover the United States, the intensity di-
| minishing gradually as the storm power be-
| comes exhausted on the way to the At
| lantic coast. The belt of the northern
| states. lying under the great eastward drift
| current is swept by these violent changes
| nearly all the winter; not infrequently
| these are projected SO far south as to
| reach the gulf states with gales and cold
waves The storms forming in, the south