Savannah morning news. [volume] (Savannah) 1868-1887, 1884-08-31
A COOL SUMNER.

What the Signal Service Statistics show
something About High and Low
Barometer-A Reminder of the Storm
of 1884.
The summer which closes to-day has
not been so remarkable a summer me-
teorologieally as many suppose. The ag-
gregate hot weather has been really as
great as during former years, but coming
at irregular intervals the hot spells have
not been so severely felt as if the swelter-
ing wave had been continuous. The
mean height of the barometer has
been below that of last year, which
would naturally indicate hotter weather.
But counteracting influences have been
favorable, and Savannah has not suffered
from extreme heat for any length of time.
July was the hottest day of the SUNNI er.
Inc thermometer registered SO at the
signal Station. Thermometers in diff
ferent parts of the city that, were in con-
tact with metals or the sides of buildings,
and which absorbed the heat radiated
from adjacent structures, may have regis
tered from one to five degrees higher, but
the Signal Service Station has the proper
exposure to get the exact temperature of
the atmosphere.
The humidity on July 6 averaged about
"a degrees. The barometer was below the
mean. The maximum temperature reach
ed during the entire summer from April
has been considerably below that of last
year. The following comparative state
ment viii show the maximum height
which the mercury has reached:
1884.
APg1. % 6SSv. Jaqe. Js'v. Argsst.
1888.
AP e % e J g J g august.
The hottest day during the month which
closes to-day was the 4th, when the mer-
curry reached % degrees. The barOmetric
observations have shown the temperature
to be irregular. To understand the Gig
nitcance of the phrases "high" and Slow
barometer it should be borne in mind that
the barometer is a measure of the weight
OF the air. The column of mercury in
the tube of the thermometer is balanced
by the column of air resting upon the
lightest when it is warm and humid, and
the barometer falls. 1t is heaviest when
1t is cold and dry, and the thermometer
rises. Like as any other fluid would be-
have under similar circumstances. the air
flows from where it is heavy to where it
is light, and the phrase "cold wave''
literally describes the physical fact.
If the air was densely colored like sea
water its surface to a celestial observer
would present the appearance of an
ocean with waves on gigantic scale, and
the Significance" of the phrase, through
of low PRESSURE" used in the weather re-
ports, would be visual phenomenon.
The closer together the area of highest
barometer and area of lowest barometer
the more violent are the winds, the high
wave, of course, falling into the deep hol-
low with greater force and rapidity than
where the elevation and depression are
moderate. The barometric observations
made simultaneously over an extensive
area of country gives notice of the hills
and hOlloWs in the air, thus affording data
for predicting the direction of the aerial
currents. Other instruments give the
humidity of air and the point of tempera-
ture at which precipitation Of moisture
takes place, and it is upon such data that
the weather prOgnosticatiOns of a signal
service are based.
The storm which passed over and
around the city yesterday afternoon was
not so violent as many supposed. The
continuous thunder and lightning. and
gave the impression that it was more ex-
tended than it really was. The rain
gauge at the Signal Station showed fall
of little over an inch and half, which
is considerably less than during the heavy
showers earlier in the summer. The wind
blew fresh, and for about five minutes
moved at velocity of "a miles an hour.
1t was quickly over and no damage of
any extent was reported. At Tybee the
storm was even less violent than in the
city. AS it began to blow many recalled
the great storm of 1881, and some of the
more timid were fearful of a recurrence
of that dread disaster,