Evening star., 1942-05-26
Of Stors, Men
And Atoms
Notebook Of Science Progress
In Laboratory, Field
And Study sA
By Thomas r. Henry.

BY Thomas r. Henry.
The year 1s45 promises to be the solar
systems midwinter." ,...
Then the suns radiation, source Of
all light and heat on earth, will reach
its lowest point in 23 years.
This is the conclusion OF DR.. Charles
G. Abbot, secretary of the Smithsonian
Institution, and his colleagues, L. B.
Aldrich and w. H. Hoover, who re-
Gently have published q revision Of daily
solar constant measurements for 20
years.
The conclusion, it should be explained,
is not that the earth, or any particular
spot on 1t, will be colder.
This would be true only If the planet
were an airless, waterless globe where
none OF the other factors that in
f1uence temperature could come into
operation.
The new volume Just issued by the
Smithsonian's Astrophysical Observatory
Is the climax Of half a lifetime Of OBJ
servations made with some of the worlds
electrical thermometer competent to
detect a millionth OF a degree rise in
temperature.
Fifteen thousand measurements were
made at 5000 feet elevation on Mount
Montezuma, Chile, where not an inch
of rain falls in a score of years. Ten
thousand more were made on Table
Mountain in the Mojave Desert Of Cali
fornia, and 1000 others on Mount st.
Katherine In the Sinai Peninsula.
The heat Of the sun, DR.. Abbot's cal
culations show, varies from month to
month with the complex Intervening
of IA cycles.
Fourteen different regular factors,
each OF which Is entirely independent
except that they all At into a period of
273 months. are influencing the amount
of radiation which the sun is radiating
into space. One factor may be operat-
ing at any particular time to increase
this radiation. Another factor may be
operating at the same time to decrease it.
The meaning of cycles in solar tenn
perature may be illustrated by familiar
periodic influences of the temperatures
Of any particular spot on the earth's
surface. There Is, for example, the
regular 12-month cycle Of the year, due
to the orientation OF the sun with
respect to this planet. Everything else
being equal, temperatures in the North
ern Hemisphere will become proges-
sively lower from midsummer to mid
winter. Any particular day in January
should be considerably colder than any
particular day in July.
There also Is the 24-hour cycle. The
temperature drops as the sun goes below
the horizon and-egain everything else
being equal-should decline from sunset
to sunrise. These two cycles are inde-
pendent of each other. But their lowest
dips should coincide once a year shortly
before sunrise some day in midwinter
II there were no other factors to be con-
sidered, this should be the coolest time
Of the year. It seldom actually would
happen this way, because so many other
factors, which do not follow known
cycles. influence the worlds weather.
The IA periodicities found by Dr. Abbot
in solar radiation, each following inde-
pendent time curves, promise in 1945 to
be at points in relation to each other
where the balance In favor Of the cooling
influences will give 23-year minimum
Of solar radiation.
AL OF them, DR.. Abhot's calculations
show, have least common denomina-
tor Of about % years. The last low point
was reached in 1922.
It is difficult to predict the influence
on the worlds weather. At first thought
it would seem logical that the earth
should be cooler, the less heat received
from the sun. The operations of the
terrestrial weather engine" are so COM
plex, however, that even the opposite
might be the case, for q decline Of solar
heat means decline Of cloudiness, and
this, in turn, affects temperatures and
rainfall differently In different parts Of
the world.
That there will be some marked effect,
probably different for different places.
hardly can be doubted.
The present investigation depended on
a recalculation Of solar constant values
the solar constant Is the accepted unit
of measurement for solar radiation fall
ing on the earth-by the staff OF the
Smithsonians Astrophysical Observatory.
Calculations in the past had not taken
sufficiently into consideration the in
visible ultraviolet component Of solar
radiation IN which the most marked
fluctuations take place. But even when
full allowance was made for these, very
little difference was found from previous
calculations by DR.. Abbot.
Among the determinations Of the new
study is that there is little discernible
relation between solar radiation per sc
and the numbers Of sunspots. This was
surprising because it is recognized that
prevalence Of sunspots-supposedly great
cyclones in the suns atmosphere-infiu-
ence the weather.
This can be accounted for, DR.. Abbot
found, by the now accepted fact that a
sunspot constantly is shooting into space
great streams of minute particles, some
of which penetrate the earth's atmos-
phere. BY changing the electrical struc-
ture Of the atmosphere, they have an
often sensational effect on radio trans
mission. But these minute particles, he
points out, also serve as nuclei for the
condensation of water vapor in the upper