New-York tribune., 1901-07-29
CYCLES IN WEATHER.

When an exceptionally long and hot summer
like that of 1900 is followed by such high tenn
peratures have prevailed for the last few
weeks over a large part of the United States
there is strong temptation TO suspect that the
climate is undergoing a permanent change. EX-
pert meteoroogists do not sanction that notion,
however. They assert that the most marked
characteristic of the weather is that II varies
much of the time from the proper standards
for region and season. Nearly every day Is
little hotter or colder than the average for many
years previous. And it is common for abnor-
may high or low temperatures to persist for
weeks or months. But these eccentrcities. we
told, are compensated sooner or later by op-
posite conditions. And The uninitiated are
warned against drawing hasty conclusions from
what must after all be regarded as merely
temporary meteorological extravagances.
Much is yet TO be learned concerning the
causes of hot waves But at least two phe-
nomena are rather closely associated with them
One is a peculiar stagnation of the atmosphere
which prevails over the central part of the con-
tinent, where they originate This unusual
sluggishness gives the heating action of the sun
a longer time 10 operate the mass, and it
proongs the effects of the wave when the latter
once starts eastward. Secondly, it is noticeable
that the most intense heat prevails in the north
eastern part of the country when a great high
pressure area which is out at sea moves in
over the South Atlantic States giving New-York
southweSterly instead of southerly breezes. One
wave traverses hot land. while the other flows
over cool sea Both the inertness of the sur
face air an1 the displacement of the ocean anti
cyclone probably due TO the behavior of the
upper currents, by means of which an inter
change is kept up between the tropics and polar
regions. And the power behind the general cir
culatOn, of course is solar radiation. But that
is about as far as it is possible to go in eX
planning hot waves.
The fact that the sun influences the weather
both directly and indirectly naturally excites
speculation as TO the possibility of fluctuations
in the thermal output of that body. The differ
ences of temperature which any locality expert
ences from day TO day are caused mainly If not
altogether by changes of wind direction, humid
ity and cloudiness, rather than variations in
solar energy. 1t is not unlikely that the latter
occur. however, and astronomers and physicists
have for years been trying TO detect and meas
ure them. Thus far but little definite informa-
tion has beer secured. The task is compli-
Gated. but not necessarily hopeless. Langley's
new method of investigation for instance, may
prove exceedingly fruitful From an instrument
gree il is not unre tsonable to expect much.
A number of people have thought that they
have found cycles in the weather corresponding
to the eleven year sun spot period or TO longer
periods of solar activity which are less con-
spcuous Much of this work is open TO the OBJ
lection that it represents only single place or
a comparatively limited district, instead of the
whole world. If there are systematic fuctua-
tions in solar energy they should produce effects
all around the earth. No periodicity in weather
due TO changes in the sun can be satisfactorily
proved without data from the Arctic and Ant
arctic South America and Africa as well as
from North America Europe and Asia. The
records should extend a long term of
years, too. And unless the observations
made with high grade instruments exposed
under uniform conditions. they would not afford
sound basis for comparison Nevertheless the
suppostion that exceptionally hot weather
comes in cycles of eleven. thirty-fiye sixty
years is entirely credible, and some day may be
established conclusively.