National Republican. (Washington City (D.C.)) 1872-1888, 1884-10-11
THE RED SUN SETS.

Old Theories Proved Faisc-Niiliions
Of mcteored Particles Rejecting Red
Light.
The red appearance Of the western sky
after sunset is again attracting attention.
When this phenomenon was observed last
fall many ascribed it to be the result Of
the volcanic eruption in the East Indies.
There has been no volcanic eruption re-
Gently, and this fact will prove that the
volcanic theory was erroneous. Another
theory advanced was that the atmosphere
had been for some timo in stagnant con-
dition and became full of impurities, such
as dust, the latter rejecting the light
from the sun after 1t had set. Still
another theory, that tho warm dry
weather caused an accumulation of mois
ture in tho air, q portion of which begins
to be precipitated rs the temperature of
the day declines. The every day redness
is accounted for by the simple experiment
Of transmitting the suns light through
glass prism, when it is found that the
spectrum changes with the altitude of the
sun, as the sun approaches the horizon
tho violet part of the spectrum contracts
and at length disappears altogether while
the red end of the spectrum remains
entire, aud hence whence the sun is near
the horizon. its light exhibits an excess
Of those rays bordering on the red end Of
the spectrum, and this red color is
communicated not only to the evening
sky but also to minute clouds which float
in the atmosphere. The theory is that
an excess of moisture in the air will pro-
long the redness of the sky for consid-
cradle time. Where there is no moisture
darkness begins with the set of the sun.
In regard to the dust theory, 1t ID ad-
mitted that the many rejecting surfaces
will reflect the light, but in order that
this reflection should continue for an
hour or more this dust would have to be
in the upper region of the atmosphere
for the reason that as the sun descends
below the horizon the particles in tho
lower stratum would be cut of from the
light and there could DO no reflections,
and the light received must be from par
the angle of the sun as it
descends below the horizon it will be
seen that in from twenty to thirty min
utes IL will be necessary for its light to
fall on a rejecting body at least ten miles
above us before we would get the reflec-
ton. At the height of ten miles the
pressure of the air is about one.eigh-
teenth of what it is at the earth's surface.
Consequently it would not have sufficient
density to float anything; so it would be
impossible for the dust to be found al
this elevation. The ordinary twilight
must be caused by reflections on sub.
stances less than ten miles: but this red
ness of the sky continues for a full hour
and we must look beyond the altitude Of
ten miles for some substance which will
reflect the light. About this season Of
the year tho earth in its orbit passe:
through what has been generally called
the meteoric zone. This cosmcal matter
is at q sufficient distance to cause the
reflection which will continue for ar
hour, or in other words prolong the twi
light. Every thirty.thr years the earth
passes through tho densest portion of THU
nebular or meteoric matter. The nearer
, the earth Is to the center the longer VIZ
have the red sky and more brilliant thu
, color. Last year may have been the
thirty-third year period. If such is thu
case this year these sunsets will be less II
, number than last year. and will not con
tinue so long in the evening. Tho red
ness of the sky is, therefore, due t.
, cosm ical matter. The theory of moistur,
, will not do, for the reason that the cirru
clouds have the greatest elevation, beyond
whose formation there can be no moisture
and this elevation Is considerably les
than ten miles. In summer u brillian
, red sunset, lasting from fifteen to twent.
minutes, is due to the impurities ant
moisture in the lower stratum, or at al
elevation less than ten miles.