Evening star., 1935-07-28

those disturbed regions on the SUM- BY analyz-
ing these distorted light waves with the spec
troscope the astronomer can tell Just how
strong the magnetic force is in the vicinity of
sun spots.
But it doesn't take spectroscope to tell us
when these electromagnetic disturbances
take place on the sun. for these sun spots
have way of disturbing the electrical and
magnetic conditions on the earth in most
uncanny fashion At times sensitive compass
needles are disturbed in a most violent
manner
This connection between affairs on the
earth and affairs on the sun has been observed
for more than hundred years. 1t is only
since the days of radio, however, that we have
learned definitely that sun spots seriously
affect the upper atmosphere. Trouble begins
in the stratosphere, which, it seems. is be-
coming favorite resort for balloonists. In
this stratosphere and far above it, where there
are never any clouds to screen the suns rays.
the suns radiation and the disturbances in it
do most of their mischief. 1t is from the upper
layers OF this stratosphere that the electric
waves from broadcasting stations are bounced
back to earth so that you may pick them up
in your receiving set. Without this rejecting
layer in the upper atmo0 phere, large part of
the broadcast waves would go out into space
and radio advertising wouldn't be very pop
ular, unless one was trying to sell ideas to the
Martians or the Man in the Moon.
1t seems strange to think of the upper part
OF the atmosphere, next to nothingness, as
rejecting back radio waves, for there isn't
very much of anything up there that one can
think of as providing rejecting surface. But
the truths that conditions are just right there
for the existence of electrified charges on the
few air molecules that remain; and free elec-
irons just delight in playing around in that
upper strata where there is plenty of room to
move without colliding with one of their fel-
lows too often.
Now, these ions and electrons in the upper
atmosphere are constantly being manu-
factmed by sunlight. And yes, also by cosmic
rays, although the amount they produce is
small compared to those due to the rays ofthe
sun. 1t is primarily the ultraviolet rays from
the sun = the kind that give us sunbun at
the seashore - that, pouring their energy on
the molecules in the upper atmosphere, split
these molecules into positive and negative
charges of electricity or, as the physicist
would say, ionize them
You see, then, that the whole earth is
really surrounded by an electrified shell, an
ionized layer of the atmosphere When the
electric waves are sent out from the big broad
casting station they 60 out in all directions. If
you are not far from the station some of these
come to your set directly over the ground;
these are called the ground waves. But part of
the waves from your broadcast station shoot
out skyward in all directions like the light
waves from an air beacon. These waves 60 on
and on until they bump against the ions and
electrons in the 'ionosphere"
This ionized layer makes good conductor
of electricity. Electric waves find difficulty
in penetrating this conducting layer and so
they are bounced back to earth at the very
same angle at which they hit, much as
tennis ball is bounced back from the ceiling
of squash court. When this sky wave hits
your receiving set it sometimes interferes very
badly with the ground wave which has come
straight to you from the broadcast station.
The result is such confusion that you ex-
perience fading and mushiness in even the
best radio receivers.
When the sun spots are few and far be-
tween. the suns radiation is not so effective
,y.s L.