Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1890-08-09
WHY THE SKY IS BLUE.
Various Prominent Heavenly Tints Ana
lived.

| fyKed.
| From the Cincinnati Times-Star.I
"You have all noticed said the Pro-
| fessor, 'sthat when we look away from the
sun into the cloudless sky the heavens APP
pear blue; when, however, we look in the
direction Of the sun, especially when,
after sunset, we look toward the western
horizon, the color is yellowish red
With the spectroscope it can be shown
that the white light from the sun is pro-
duced by mingling of different colored
rays. Indeed this can be shown by means
of any triangul.-r prism, say one of the
pendants of chandelier One of these
placed in the path of a beam of light will
project on screen band of seven colors
red, orange, yellow, green, light blue,
dark blue and violet. Understanding
this, we can readily see how the effect is
blue when piece of blue glass is inter-
posed, or red when red glass is used. All
but the blue and red rays respectively are
absorbed; these, however, pass through
freely, and we say that the body is blue,
or red, when really the color is not a
property of the glass in any true sense,
but of the sunlight. What has this to do
with the sky colors? l will now show
you.
dissolve little white CASTLE soap in a
tumbler of water, so as to make the water
slightly turbid. Place a black screen be-
hind the tumbler and hold the whole so
that the sunlight must be reflected from
the liquid before it can reach your eye.
The liquid will appear blue. Hold it next
in direct line toward the sun and it APP
pears yellowish red Now these are the
exact appearances Of the sky. Sky light
is refracted light. The water particles in
the atmosphere, like the particles of soap
in the water, refract blue light; while the
background of darkness surrounding the
earth replaced the black screen. The
atmosphere, like the solution of soap and
water, transmits yellow and red rays but
slightly refracted, while the blue, being
weak color, is refracted too low to be seen
hence when we look toward the source of
light in the evening or morning the sky is
of yellowish red color This effect is
more pronounced then than during the
day, because when the sun is near the hor-
lion the rays travel Il greater distance in
the air in order to reach the earth than
when directly above Us. Consequently
the blue rays are more thoroughly re-
fracted
"The atmosphere has many effects in
modifying the appearance of the sky and
the heavenly bodies. Look at Venus over
there near the horizon and Just below the
crescent moon, which has come into plain
view while we have been talking ION ac-
count of the deepening darkness). Its
real distance from the horizon is not as
great as it appears, for the rays of light
which it reflects to us, and which it re-
ceives from the sun, are bent downward
when they pass into our air, perhaps fifty
miles from the earth's surface.
GAS the effect is the same as that which
would be produced were there no atmos-
phere, by rays proceeding from higher
star, we locate the body in more elevated
position than the one which it actually &C.
cupies. Put a dime on the bottom of
pail filled with water and you have like
conditions with similar effect. If you
place your hand where you think that you
see the coin you will not touch it, but
spot perhaps an inch above the true bot
tom.
"Again, do you notice how steadily
Venus shines? If you are here an hour
later, when the stars are all out you will
observe that all those near the horizon,
the others to a smaller extent, are merrily
twinkling. This appearance, made ia
miliar to all of US by the old nursery
rhyme, Twinkle, twinkle, little STAR is
not noticeable in the case of any planet
except Mercury, and las been the subject
of much study on the part of scientific
men; it is now generally believed that it
arises from the unequal blending OF the
rays of light as they pass through aerial
currents of different temperatures and
densities. The facts seem to support this
theory, for where the air is the densest-
near the horizon-the effect is most notice
able, where it is the rarest-in our zenith
ii is less marked"