The Sunday herald and weekly national intelligencer., 1891-10-04
1T is OVER NOW.
But the September Hot Spells Was a
Sumner while It Lasted.

The unusual hot spell which recently pre-
vailed all over the United States was phe-
nomenal one for the period of the year in
which 1t occurred. Since the establishment
OF the Weather Bureau twenty years ago
nothing like it has been known. During the
week ending September %, the temperature.
was from 80 TO 21o higher than the mean
temperature of that week for the previous
years. The greatest increase was In Wisconsin
and Minnesota, where the heat became 30 in
tense that schools were closed and vacation
extended until break in the weather came
This change appeared in the Northwest the
first of last week and gradually extended
eastward until 1t reached the Atlantic Coast
and New England on Wednesday At the
Weather Bureau the change is believed to be
a permanent one and any continued hot
weather is not expected.
Naturally this condition of the atmosphere
was the cause of considerable speculation and
reason for it was sought The officials of
the Weather Bureau assign 1t to three distinct
atmospheric conditions which combined to
make the recent weather remarkable. The
stagnation of the atmosphere is assigned as
the principal cause. This was due to an
entire absence of currents in the upper
L
had been little or no winds to give
to the strata of atmosphere that motion
which causes the lower or more heated
strata to become intermingled with the
upper or cooler ones and thus bring about a
mean temperature. But no winds came to
cause this motion and each day the heat of
the earth raised the temperature OF the atmo-
sphere, thus causing the hot stratum of air
which is next to the earth to become thicker
until 1t is believed 1t reached height of some
5000 or 5000 feet. 1t formed, as 1t were, a
blanket to the earth and kept all the heat be-
meath 1t. A cumulative atmosphere is the
meteorological term applied to these phenom-
ina An atmosphere whose heat is added to
each day.
A second condition which tended to increase
the temperature was as unusual as the degree
of temperature itself. A factor which, as
rule, tends to cool off the air, is that after
storm there generally follows wave of cold,
pure air which has its beneficial effects during
the period referred to here. One storm after
another came SO quickly from the Pacific over
the northwest that the usual cool wave was
absent and consequently the storms only
added Humidity to the atmosphere and
brought with them nothing to lower the tenn
perature
The third cause was the fact that what
little breezes there were, came from the south
and southwest and bore with them only
more intense degree OF heat.
those not informed on meteorological topics,
to be the direct rays Of the sun, which shone
on the earth for two weeks almost without
cloud to come between them for moment to
give any shade. But this could not be, as the
sun crossed the line on the 23d instant, and
is far from the earth. Its rays come now
only at very oblique angle aud could not
therefore produce very great degree of heat.
The very fact that for fortnight, both day
and night, the sky was unclouded, gave those
meteorologists who do not believe that radia-
tion is the only factor which causes coolness
an excellent opportunity to combat this
theory. They say that during this extreme
weather the conditions could not have been
more favorable for radiation, but still the
temperature remained the same. The scientists
of the 'anti-radiation" theory believe that
cooler temperature or cold wave is produced
primarily by wind storm which causes the
various strata of air to be distributed to the
very greatest extent SO that the strata at n
height of 10000 feet, where the temperature is
below zero, comes in contract with the hotter
ones and produces cold.
The blizzard, they say, is always accom-
panied by a terrific wind storm. 1t was such
a condition which finally broke the hot spell
and brought relief to suffering humanity. A
storm from the Pacific at last got over the
Rocky Mountains and causing disturbance
Of the atmosphere broke the stagnation and
cold wave set in The temperature in Dakota
dropped to freezing point and soon the whole
country felt the benefits of it,