Evening star. [volume] (Washington, D.C.) 1854-1972, 1891-06-20
Written for The Evening Star.
THE HEATED TERM.
How ~the Weather" 4. Made.

The heated term" extending over a large
portion OF the United States. June IS. I6 and ~,
and the change and reduction Of temperature
on the 18th presents a fne meteorological
study. Years ago or even without the light OF
the present, such phenomenon could not be
understood nor intelligently discussed. And
vet many still ignore the light and thereby ex-
pose their ignorance, when with their intelli-
gence they might readily grasp the principles
that govern these atmospheric conditions. and
even more, they might readily become readers
of the signs and thereby prophets themselves.
As often stated in these columns the source
from which this wonderful information can be
so readily obtained is the weather man 40 CON-
spicuously placed about the city. After 80
much has been written il would seem unneces-
sary to enter largely into the details Of high
and low enough 20 repeat the general state
ment that high" is the cool. dry factor, and
that low" is the wet factor, and cold
or warm in proportion to it's latitude, and
that the status of these factors likewise have q
controlling influence in making what we term
''the weather. The more intense the high
the colder J: will be for the season.; the more
Intense the low the more general and intense
will the storm be. By general storm" we
mean condition Of precipitation over an ex-
tended area. say Of 500 miles or more. BY
local storms" we mean those conditions far
take place here and there over a wide area.
The atmospheric condition for locale" IL a
relatively high latitude ''low," with a moderate
high to the south. Thirty inches pressure
OF the atmosphere is. say, normal Amoderate
high would be 80 i" 20 3O'3'', an intense
high 800 and upward. The moderate
low will be 29.9". The intense .low''
29 A and downward
humidity Is one of the essential features of
low, and when II is upon the atmosphere
a NJ .Nr.R. n.
approaching or upon us the atmosphere is
clear and ''brncing"
The wind Is from the high to the slow IS
80 when a north low prevails the wind il
from the south. These flows" in their course
over the country often travel eastward through
the 81. Lawrence valley, and when they do
thus travel, say on line of SIS degrees to 20
degrees north latitude, the winds all over the
eastern section of the United States are neces-
sarlly from the south. And il there is no very
good or positive high in the southern por-
ton of the United States these airs from the
south Will be warm. and as they come within
the low limits will be more or less burdened
Win moisture and thereby engender that
peculiar effect known as CLOSE"
Now, ON these three days, the 18th, 10th and
ION OF June, moderate north ''low' pre-
vailed with the center way up in Canada to-
Sether with moderate .'high" to the south
ana along the Atlantic seaboard. This was
period and condition for locals. and thew took
place here and there all along the lines. accom-
panied with more or less thunder and lightning.
what would change this terrible condition!
one OF two conditions would accomplish it.
Which would it be. the pressure of a high" or
low on lower line of latitude? The map
o: the 18th indicated no high" near enough to
make any material change. SO there was little
hope from that source. But in the
meanwhile slow was espied march
ing on a lower line. At the a. m.
observation of the 18th this new ''low" CEN
tered IL Illinois. BY 1880 O'Clock am. the
effect was quite manifest in Washington and as
the day wore on and this ''low" on this more
middle line advanced, it produced its effect.
By evening the thermometer had fallen some
70 degrees and good rain came. with a little
thunder and lightning Had it not been for the
heat from the preceding north or high latitude
low We would not have had this little cleo
trical display. 1t would seem that there was
beauty enough in this grand system TO induce
more of the intelligent classes at least to in
terest themselves In this wonderful illumina-
tor - the weather map-whereby and only
whereby We are enabled TO know so much about
tine conditions of our atmosphere. l. p. n.
June Is, 1891.