Evening star., 1901-08-24
CYCLES ~ WEATHER.
Much is Yet to BE bearned Coneernfng
Extremes inITemperature.

M
Extremes inITemperature.
From the New York Tribune.
When an exceptionally long and hot sum-
mer like that of 1909 Is followed by such
high temperatures as have prevailed for
the last few weeks over a large part OF
the United States there is strong tempta-
ton to suspect that the climate is under
going a permanent change Expert meteor
oiogists do not sanction. that notion. how
ever. They assert that the most marked
characteristic OF the weather is that 1t
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
1t Is common for abnormaly high or low
temperatures to persist for weeks or
months. But these eccentricittes, we are
told are compensated sooner or later by
opposite conditions. And the uninftiated
are warned against drawing hasty conclu-
sions from what must after all be re-
garded as merely temporary meteorological
extravagances.
Much is yet to be learned concerning
the causes of hot waves. But at least two
phenomena are rather closely associated
with them. One is a peculiar stagnation
of the atmosphere which prevails over the
central part of the continent, where they
originate. This unusual sluggishness gives
the heating action of the sun longer time
to operate on the mass, and 1t prolongs
the effects Of the wave when the latter
once starts eastward. Secondly, 1t is no.
ticeable that the most intense heat pre-
walls in the northeastern part Of the coun-
try when great high pressure area which
is out at sea moves in over the south At
lantic states, giving New York southwest
erly instead of southerly breezes One
wave traverses hot land while the other
flows over a cool sea. Both the inertness
of the surface air and the displacement Of
the ocean anti-cyclone are probably due to
the behavior of the upper currents by
means of which an interchange is kept up
between the tropics and polar regions And
the power behind the general circulation,
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 natu-
rally excites speculation as to the possibil-
ity of fluctuations In the thermal output OF
that body. The differences Of temperature
which any locality experiences from day to
day are caused mainly, IL not altogether
by changes of wind direction, humidity and
cloudiness rather than variations In solar
energy. 1t is not unlikely that the latter
occur however. and astronomers and physi-
c1stS have for years been trying to detect
and measure them. Thus far but little
definite information has been secured The
task is complicated, but not necessarily
hopeless Langley's new method Of inves-
tlgatiOn, for instance, may prove exceed
ingly fruitful. From an instrument that
lcSiSteIS OlHeTenCeS OF q mlilOnth or q de-
gree 1T is not unreasonable 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 conspicuous Much of this
work is open to the objection that it repre-
sents only single place or a comparative
iy limited district instead Of the whole
world IT there are systematic fluctuations
IN solar energy they should produce effects
all around the earth No narjpdicify in
weather due to changes ip the sun can be
satisfactorily proved without data from the
arctic and antarctic South America and
AFRICA, as well as from North America
Europe and Asia The records should ex-
tend over long term of years. too And
AhIess the observations ARE made with
high-grade instruments exposed under uni
form conditions they would not afford a
sound basis for, compar rison. Nevertheless.
the supposition that exceptionally hot
weather comes In cycles 4of eleven, thirty
hve or sixty years is entirely credible and
some day may be established =conclusively.