Evening star., 1932-05-03
NEW BAROMETR|C
WEATHER ER|ND|CATOR
DESCRIBED HERE
MeteoroIogistS Told of Rela-
tionship of Pressure in Bis
marck and Savannah.
Thermometer RECORDS
FOR 20 YEARS STUDIED
Comparison of Two Stations Gives
Almost Perfect Key to Wind and
Temperature Elsewhere.
BY THOMAS r. HENRY.

A new weather indicator was de-
scribed before the American Meteoro-
logical Society yesterday afternoon by
]. B. Kincer, head of the division of
agricultural meteorology of the Weather
Bureau.
Analysis of temperature records OF
the East and Central United States for
the past 20 years, Mr.. Kincer says.
shows that the long period variations
are related closely to the Savannah
Bismark pressure gradient. Thls IS
the difference, observed daily. between
the barometric pressure at Savannah,
Ga, and Bismark, S. D. When the
Savannah pressure is higher than that
recorded at Bismark a large section Of
the country can expect warm weather
and. other things being equal, the
greater the difference the warmer the
weather. The reverse also is true.
Close Relationship Cited.
Mr.. Kincer presented statistical cor
relations between this pressure gradient
and the Thermometer readings at Chi
cago and the wind records at Lexington,
KY, and in each case there was close
relationship. He sought this relation
ship to explain some of the long-period
temperature changes, such as the in
creasing warmth of the past 10 years
which eliminated in the extremely warm
Winter Just past. These have been ex-
planned as due to an area of high
pressure over the Southeast which
blocked the cold highs" sweeping down
out of the Arctic by way of the Nc
KenZie Basin and then southeastward
across the United States. Kincer found,
however. that during some Of the abb
normally warm periods the Southeastern
pressure was not actually very high.
The difference appeared in the magni-
tude relative to the Northwest.
Actually, he explained, gradient line
between any point in the Southeast and
any point in the Northwest would serve
as well as that between Savannah and
Bsmark 1t happens, however, that
reliable weather observing stations have
Deen located at these points for many
years so that a constant comparison can
be made.
I4-Year Trend Shown.
Ever since the abnormally cold war
Winter of 1918, he said, the Bismarck
pressure has been going down relative
to the Savannah pressure. The curves
show that the Savannah pressure has
been at points of maximum superiority
over the Bismarck pressure in 1913,
1921 and 1881, and each of these years
has had an abnormally warm Winter.
There is hint here of a 10-year cycle
closely allied with the 11-year sun spot
cycle, Mr.. Kincer said, but the 20-year
data is insufficient to justify such an
Interpretation.
Cho IN tho YNroccIIra Gradient cppU0
to be reflected over the country very
rapidly, he pointed out. An increase
usually becomes apparent in Chicago
the next day, and presumably most of
the midcontinent stations would feel
the same effect The relationship Is
most marked in the Fall. Kincer
showed however, that the other three
seasons are almost as closely affected.
The pressure gradient seems most
closely related to wind velocitieS, he
said, in March. Curi0usly enough
this is the month when the gradient
is likely to be most pronounced, and
also when winds over most of the
United States are strongest. The COM
parison was made with winds at Lex
ington because this city is so located
that its winds respond directly to far
reaching meteorological conditions with
out much strictly local effect. The
pressure gradient hypothesis, Kincer
pointed out, gives scientific basis to
the firmly entrenched popular concep-
ton Of March as the windy month"
During the Summer the pressure gradl-
ent is less pronounced. This Is also the
season when winds are lightest and
when temperature changes are less
the country over.
Comparison Is Necessary.
The actual pressure over Savannah,
he said, gives little indication OF what
is happening on the meteorological map
unless the comparison with the BIS
mark pressure is made. Great increases
in Savannah pressure, taken alone
usually are accompanied by increasing
temperature, but the correlation be-
tween them and the Chicago. ther-
mometer is only % compared to a
correlation Of .90-almoSt as high as 1t
is possible to obtain-between the lat
ter and the Savannah-Bismark gradient.
Forest fires seem to respond directly
to humidity changes, T. E. Reed Of the
Weather Bureaus Boston office told the
meteorologists. He presented study
of the weather factors involved in the
fires which sweep over New England's
$4,000, 900 acres of forest and which,
in the Spring and Fall, show a close
relationship to the actual humidity
from day to day.
W. t.,,,a country covered by net
work of stations established in the serv-
ice of aviation, said w. r. Gregg of the
Weather Bureau, the technique of
three-hour forecasts for any particular
locality is being perfected.
A new explanation OF the mechanism
of storms operating in the upper at
mosphere, based on data from airplane
escents and pilot balloon observations,
was presented by L. P. Harrison of the
Weather Bureau.